Algonquin College

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Course Description

This course provides a basic overview of the Anatomy and Physiology of the human body and is designed for learners with little or no prior knowledge of biology. The materials and interactive learning activities allow for a self-paced progression though the course and each module ends with an optional quiz to assess your understanding of the materials covered. This is an excellent beginner level course and is a great way to prepare your self for either our 45 or 60-hour online credit course in Anatomy and Physiology.

subject
Human Anatomy and Physiology
author
Kyle Scott, Julie Warrington, Melissa Smeltzer, and Glenn MacDougall
level
Beginner
duration
16 weeks
additional features
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A band

region of a sarcomere where actin and myosin filaments overlap; corresponds to the darker stripes of striated muscle [top]

Abdominal Muscles

Muscles of the abdomen which aid in respiration. [top]

Abdominopelvic Cavity

A ventral cavity consisting of the abdominal cavity (between the diaphragm and the level of the pelvic bone) and the pelvic cavity (between the top of the pelvis and pubic area). Ex. The intestines and stomach are found in the abdominopelvic cavity [top]

Abduction

movement of a limb away from the middle of the body, generally in the frontal plane. Abduction is the opposite movement to adduction. Ex. You raise your arm upwards and away from your body [top]

Absorption

The process of being absorbed [top]

Accessory Organs

An organ that aids in digestion but is not part of the digestive tract such as the liver and pancreas [top]

Acetylcholine

A neurotransmitter of the parasympathetic nervous system that is responsible for transmitting nerve impulses across synapses [top]

Acidosis

An abnormal increase in acidity of body fluids caused by acid buildup or bicarbonate depletion [top]

Acinar Cells

Spindle shaped cells of the pancreas that secrete hydrolase enzymes which break down peptides, disaccharides and triglycerides. [top]

Acrosomal

The anterior end of the spermatozoon which releases ovum-penetrating enzymes [top]

Acrosome Reaction

The exposing of the acrosome as the sperm reaches the zona pellucida of the ovum so that enzymes may be released in order for the walls of the ovum to be penetrated and fertilization to be accomplished. [top]

Actin Filaments

thin filaments; form part of the contractile filaments in muscle [top]

Action Potential

A depolarization event that occurs between the inside and outside of a nerve or muscle fiber when it is stimulated. [top]

Action Potential Propagation

The process by which an action potential spreads throughout a neuron [top]

Activation

To start or make active [top]

Active

Requires energy for a specific process [top]

Active Expiration

The forceful expelling of the air from the lungs (such as during coughing) [top]

Active Reabsorption

The movement of a substance against its osmotic gradient from the filtrate in the nephron into the blood with the use of energy. [top]

Active Transport

Cell transport in which the movement of substances across the cell membrane is driven by energy input from ATP. Active transport is used to move substances from an area of lower concentration to an area of higher concentration. Ex. Vesicular transport is a type of active transport [top]

Acquired(conditioned) Reflexes

A response to a stimulus after conditioning has taken place [top]

Adapt

To adjust to different conditions [top]

Adaptive Body Defenses

Response of the immune system to specific pathogens; involves humoral and cellular immunity. [top]

Adduction

movement of a limb towards the middle of the body, generally in the frontal plane. Adduction is the opposite movement to abduction. Ex. You lower your arm towards your body [top]

Adipose Tissue

fatty tissue; consists of adipose cells which store fat droplets and very little matrix. Ex. Found in subcutaneous region, surrounding some organs and in some deposits in the body [top]

Adrenal

Related to or produced by the adrenal glands [top]

Adrenal Cortex

The outer part of the adrenal gland that secrets corticosteroids and sex hormones [top]

Adrenal Glands

A pair of endocrine glands located at the cranial poles of the kidneys that are comprised of an outer cortex which secretes glucocorticoid, mineralocorticoid and androgenic hormones and an inner medulla which produces epinepherine and norepinepherine [top]

Adrenergic

Activated by adrenaline or similar to adrenaline [top]

Adrenocorticotropic Hormone (ACTH)

A hormone secreted by the anterior pituitary gland that stimulates the adrenal cortex to secrete cortisone and aldostorone. [top]

Adenoids

A lymphoid growth located at the back of the pharynx which may obstruct normal breathing if it becomes swollen. [top]

Aerobic

Requires oxygen for life [top]

Aerobic Respiration

conversion of glucose (in the presence of oxygen) to carbon dioxide and water, producing approximately 36 ATP per glucose molecule. Can supply muscles with several hours of energy with sufficient glucose and oxygen. [top]

Afferent

Towards the center. Ex, an afferent neuron carries impulses toward the central nervous system [top]

Afferent Arteriole

Brings oxygenated blood at high pressure into the glomerulus. [top]

Afferent (sensory) Division

Portion of the peripheral nervous system consisting of afferent cranial and spinal nerves that send sensory information to integration centers in the brain and spinal cord [top]

Afferent Lymphatic Vessels

Lymphatic vessels which carry lymph towards the lymph node. [top]

Aggregation

A collection or cluster of particles, parts or bodies [top]

Agonist

In pharmacology; a drug that mimics the normal neurotransmitter for a receptor [top]

Air-Blood Barrier

A barrier located in the gas exchanging region of the lungs to prevent air bubbles from forming in the blood. [top]

Alarm Stage

A short term stress response activated by the sympathetic nervous system where heart rate increases, bronchioles dialate and glycogen is broken down into glucose. [top]

Aldosterone

A steroid hormone of the adrenal cortex which stimulates water retention by the kidneys, increasing blood pressure. [top]

Alimentary Canal

The tubular passage beginning at the mouth and ending at the anus which functions in the ingestion, digestion and elimination of food. [top]

Alkalosis

A condition involving an abnormal increase in bicarbonate in the blood causing increased alkalinity in the body. [top]

All-or-nothing Response

response regulated in an "on-off" fashion with no increments; opposite to a graded response [top]

Allurin

Chemical attractant released by a mature ovum to attract sperm into the correct oviduct [top]

Alpha Cells (Alpha Islets)

Endocrine cells within the islets of Langerhans in the pancreas which synthesize and secrete glucagon, elevating blood glucose levels. [top]

Alpha Islets (Alpha Cells)

Endocrine cells within the islets of Langerhans in the pancreas which synthesize and secrete glucagon, elevating blood glucose levels. [top]

Alpha Receptor

A receptor on a nerve cell of the sympathetic nervous system that causes vasoconstriction, pupil dilation and intestinal relaxation when combined with epinerpherine or norepinepherine [top]

Alveolar Glands

Also called the mammary glands; sebacous glands that are modified to secrete milk in females. They occur in clusters with a network of ducts to allow milk to travel to an external nipple [top]

Alveolar Pores

Holes which connect neighbouring alveolar sacs of the lungs together. [top]

Alveoli (Air Sacs)

Air filled sacs of the lungs where oxygen and carbon dioxide exchange takes place [top]

Ameboid Motion

Movement resembling an amoeba [top]

Amine

An organic compound that is derived from ammonia by the replacement of hydrogen atoms [top]

Amino-acid Derived Hormones

Hydrophilic molecules that have amino acids as their main structural unit. Because non-steroid hormones are hydrophilic, their receptors are on the external surface of the plasma membrane where they indirectly affect cell activities by activating biochemical pathways in the cell. Also known as non-steroid hormones. [top]

Ammonia

A gaseous compound of hydrogen and nitrogen which is found in nitrogenous waste such as urine. [top]

Amnion

The fluid filled sac which forms around the embryo and fetus in the womb. [top]

Amniotic Fluid

The watery fluid surrounding the embryo and fetus in the womb. [top]

Amniotic Sac

The fluid filled sac which forms around the embryo and fetus in the womb. [top]

Anabolic

Something that induces constructive metabolism where simple substances are synthesized into complex substances [top]

Anaerobic

Can live in the absence of oxygen [top]

Anatomical Directional Terms

Terms used to describe the location of anatomical features. Ex. Anterior, posterior, superior, caudal etc. [top]

Anatomy

The study of the structure (shape and size) of body parts of organisms Ex. An anatomical feature of the human face is that the nose is located in the center of the face [top]

Androgens

Steroidal hormones produced in the testes that control the development of masculine characteristics [top]

Anemia

An abnormal decrease in the number of circulating red blood cells in the body [top]

Angiotensin I

The inactive form of angiotensin which is a descendant of angiotensinogen and a precursor to angiotensin II. [top]

Angiotensin II

A protein which causes vasoconstriction altering arterial blood pressure. It also stimulates the adrenal cortex to release aldosterone. [top]

Angiotensin-Converting Enzyme (ACE)

An enzyme that converts angiotensin I to angiotensin II [top]

Angiotensinogen

A globulin protein formed by the liver which is hydrolyzed into angiotensin I by renin. [top]

Antagonist

In pharmacology; a drug that blocks a neurotransmitter receptor, preventing the neurotransmitter from binding [top]

Anterior Pituitary (Adenohypophysis)

The anterior portion of a paired endocrine gland attached to the base of the brain that secretes growth hormone, TSH, ACTH, PRL, LH and FSH. [top]

Antibodies

A protein produced by B cells after stimulation by an antigen in an immune response that functions to destroy or weaken the foreign antigen. [top]

Antidiuretic Hormone (ADH)

A hormone secreted by the posterior pituitary gland that causes vasoconstriction, increases blood pressure and reduces urine excretion [top]

Antigen

Any foreign substance that enters the body and stimulates an immune response. [top]

Antigen A

A surface antigen present on A-type red blood cells [top]

Antigen B

A surface antigen present on B-type red blood cells [top]

Antigen Rh

A surface antigen present on Rh-positive red blood cells [top]

Antigen-binding Sites

Areas on the light chains of an antibody which bind to specific antigens. [top]

Antigen-presenting Cell

A phagocytic cell that facilitates the immune response by holding antigens on its surface and presenting them to lymphocytes. [top]

Antigen Receptors

Receptors located on the surface of lymphocytes that allow lymphocytes to respond to specific pathogens [top]

Antrum

The area of the stomach where the most vigorous peristaltic contractions take place [top]

Anus

The external opening of the digestive tract where waste is removed from the body [top]

Aortic Arch

The curved portion of the aorta that lies between the ascending and descending aorta [top]

Apneusis

Prolonged inspiration due to sustained contraction of the respiratory muscles [top]

Appendicular Skeleton

One of the two main divisions of the skeletal system; includes the bones of the limbs and limb girdles. Ex. Humerus, clavicle, femur, ulna, radius etc. [top]

Arachnoid Mater

Membrane forming the middle of the three coverings of the brain and spinal cord (meninges). It is attached to the dura mater but is separated from the pia mater by the subarachnoid space. [top]

Arachnoid Villi

Small protrusions located in the dura mater that allow for cerebrospinal fluid to exit the brain and enter the bloodstream [top]

Areola

The pigmented area around the nipple [top]

Areolar Tissue

Fluid, spongy tissue that can retain excess fluid during swelling; consists of fibroblasts and a loose network of fibers. Ex. Mucous membranes, wrapping body organs [top]

Arterial Blood

Oxygenated blood that is found in the arteries and the left chambers of the heart [top]

Arteries

A blood vessel which carries oxygenated blood away from the heart to cells, tissues and organs of the body. [top]

Ascending Colon

The first part of the colon beginning at the cecum and continuing upward along the right abdominal wall [top]

Aseptic Technique

A procedure performed to destroy and isolate microbes and keep areas microorganism free. [top]

Association Neurons (interneurons)

A nerve cell found within the brain or spinal cord (CNS) that links sensory (afferent) neurons to motor (efferent) neurons [top]

Astrocyte

A star shaped cell of the nervous system [top]

Atoms

The particles of specific elements; combine to form molecules Ex. A single atom of the element Oxygen can combine with another Oxygen element to form oxygen gas [top]

ATP

Adenosine triphosphate; A nucleotide that provides energy to cells for various processes including sugar metabolism [top]

Atria

Two chambers of the heart which receive blood from veins and force it into the ventricles [top]

Atrioventricular (AV) Bundle

A bundle of muscle fibers which conduct implulses from the right atrium to the ventricles in order to regulate heartbeat

Auditory Canal

The passage from the outer ear to the ear drum [top]

Auditory Cortex

The section of the cerebral cortex which receives auditory data [top]

Auditory Ossicles

The three smallest bones of the human body contained in the middle ear called the malleus, stapes and incus that transmit sound waves from the air to the cochlea. [top]

Autonomic

Occuring involuntarily [top]

Autonomic Nervous System (ANS)

Division of the peripheral nervous system that innervates cardiac and smooth muscle and allows for involuntary motor function [top]

Axial Skeleton

One of the two main divisions of the skeletal system; found along the longitudinal (vertical) axis of the body. Consists of the skull and vertebrae. [top]

Axon

The appendage of a neuron that sends impulses away from the cell body [top]

Axon Hillock

The projection from a nerve cell body where an axon originates [top]

Axon Terminals

The enlarged ending where axons make synaptic contacts with adjacent nerve cells or effector cells. Storage location for neurotransmitters before they are released into the synaptic cleft. [top]

Bacillus

Bacteria with a rod shape [top]

Bacteria

Fast reproducing, unicellular, prokaryotic microbes which live in colonies in soil, water, organic matter and animals. [top]

Bacterial Culture

The process of bacterial multiplication by adding them to nutrient media in laboratory conditions. [top]

Bacteriophage

A virus that is capable of infecting bacteria [top]

Basic (simple) Reflexes

Unlearned, involuntary responses to stimuli [top]

Basilar Membrane

A supportive membrane for the organ of Corti that extends from the bony shelf of the cochlea to the outer wall and aids in converting sound vibrations into electrical signals [top]

Beta Cells (beta islets)

An insulin secreting cell of the islets of Langerhans in the pancreas[top]

Beta Islets (beta cells)

An insulin secreting cell of the islets of Langerhans in the pancreas[top]

Beta Receptor

A receptor on a nerve cell of the sympathetic nervous system that controls heart rate and vasodilation when combined with epinerpherine or norepinepherine [top]

Bicarbonate

The combination of hydrogen, carbon and oxygen (HCO3) which gives off carbon dioxide when heated [top]

Bicarbonate Ion

An alkaline ion composed of hydrogen, carbon and oxygen which is found in saliva and pancreatic secretions and functions to neutralize food. [top]

Bile

A green fluid secreted by the liver and passed into the duodenum to aid in the absorption and emulsification of fats [top]

Bile Duct

The large duct which transports bile from the liver to the duodenum [top]

Bile Salts

A salt produced by the mixture of bile acid and base which functions to emulsify and absorb fats in the duodenum [top]

Biliary System

A system including the liver, gallbladder and associated ducts which are all involved in the production and secretion of bile. [top]

Bilirubin

A reddish bile pigment produced by the degredation of heme (from red blood cells) in the liver. An excess of bilirubin in the blood results in jaundice. [top]

Binary Fission

Asexual reproduction where a parent cell divides into two daughter cells. [top]

Biology

The study of living organisms and their environments Ex. Anatomy is a branch of biology focusing on the structure of living organisms [top]

Bipolar Cells

Specialized sensory neurons that transmit impulses of the special senses [top]

Bladder

A membranous sac which acts as a storage chamber for fluid. Ex, urinary bladder. [top]

Blastocyst

An embryonic stage where two individual cell types begin to develop: the inner cell mass and the outer enveloping layer (trophoblast). [top]

Blind-ended

A vessel that has a sealed end instead of being continuous with other vessels [top]

Block to Polyspermy

A chemical reaction which takes place inside the ovum once it has been fertilized so that another spermatozoa may not pass through its surface. [top]

Blood

Vascular tissue consisting of blood cells and a fluid matrix (plasma) and soluble fibrin proteins. Ex. Found in all blood vessels of the circulatory system; penetrates body tissues to transport nutrients, wastes, gases and other substances [top]

Blood-brain Barrier

Capillary walls made of tightly packed cells which line the brain and prevent substances from the blood from diffusing into the brain [top]

Blood Clotting Response (hemostasis)

The stoppage of bleeding or hemorrhage [top]

Blood Pressure

The pressure exerted on the walls of blood vessels by blood flow controlled by the contraction and relaxation of the heart. [top]

Blood Pressure Cuff (Sphygmomanometer)

A deviced used to measure blood pressure that is comprised of an inflatable cuff and a manometer to display the pressure value. [top]

Blood Vessels

Any tubular channel through which blood circulates, such as, veins, arteries and capillaries [top]

B-Lymphocyte

A type of lymphocyte that develops in bone marrow and produces antibodies. [top]

Body

The middle section of the stomach [top]

Bolus

A small mass of chewed food [top]

Bone (compact)

One of the two basic types of bone tissue. Smooth in appearance; continuous, dense bone tissue. Ex. Outer region of long bones is compact bone [top]

Bone (flat)

Shape classification of bone; Thin compact bone surrounding a layer of spongy bone shaped into a very thin, plate-like structure. Flat bone are often curved to fit around internal structures. Ex. skull, ribs, sternum [top]

Bone (irregular)

Shape classification of bone; Bones that do not fit into the category of long, short or flat bones, often sharing the characteristics of multiple shape categories. Ex. vertebrae, hip bones [top]

Bone (long)

Shape classification of bone; Mostly compact bone with some spongy bone shaped into a long shaft with heads at both ends. Ex. Structural support for the limbs, excluding the knee caps (patella), wrist and ankle bones. [top]

Bone (sesamoid)

Special type of short bone that form inside tendons. Ex. Patella [top]

Bone (short)

Shape classification of bone; Mostly spongy bone in small rough cube shapes. Special short bones called sesamoid bones form inside tendons. Ex. Wrist and ankle bones, patella. [top]

Bone (spongy)

One of the two basic types of bone tissue. Fine pieces of bone form a three-dimensional lattice structure filled with hollow spaces. Ex. Short bones are mostly spongy bone [top]

Bone Marrow

The soft, vascular tissue contained in the cavities of bones which acts as the site for blood cell creation [top]

Bowman's Capsule

A membranous capsule surrounding the glomerulus of the nephron. This is the site where glomerular filtrate passes into the proximal convoluted tubule. [top]

Brachial

Relating to the forelimb [top]

Brain

Mass of grey and white matter contained in the cranial cavity that serves to control mental and physical actions. [top]

Brain Circulation

The system of structures and blood vessles which carry blood through the brain. [top]

Brain Nuclei

A structure in the brain that is comprised of clusters of neurons. [top]

Braxton-Hicks Contractions

Irregular uterine muscle contractions that occur during pregnancy but are not associated with labour. [top]

Breathing Control Centre

An area of the brainstem that functions to regulate breathing depending on oxygen demand and carbon dioxide levels in the blood. [top]

Bronchi

The two branches of the trachea which connect to the bronchioles of the lungs [top]

Bronchioles

The smaller branches of the bronchi which connect to alveoli (air sacs) within the lungs [top]

Bronchus

One of the two branches of the trachea which connect to the bronchioles of the lungs [top]

Brush Border

The array of microvilli on epithelial cells of the small intestine that function in nutrient absorption [top]

Bulbourethral Gland

Two small glands that lie near the male urethra just below the prostate gland and secrete a mucousy substance that helps to make up semen [top]

Bundle Branches

Branches of the bundle of His (AV bundle) which run along the ventricular septum and include the right, left anterior and left posterior bundle branches. These branches make up the Purkinje fibers which transmit impulses from the AV node to the ventricles of the heart. [top]

Calcium

A metallic element that is a component of teeth and bones and is essential for growth in plants and animals. The symbol for calcium is Ca. [top]

Capillaries

Small, thin walled blood vessels which connect arterioles with venules [top]

Capillary Beds

A network of capillaries that supply an organ with nutrients and carries away waste. The blood supply to capillary beds is controlled through precapillary sphincters which receive input from the autonomic nervous system [top]

Carbonic Anhydrase

An enzyme contained in red blood cells which aids in carbon dioxide transport to the lungs [top]

Cardiac Cycle

A single complete heartbeat consisting of systole (contraction) and diastole (relaxation) of the ventricles and atria of the heart [top]

Cardiac Muscle

Muscle tissue with light striations composed of branched cells with a single nucleus joined by special junctions (intercalated discs). Functions in the involontary contractions of the heart. Ex. Found only in the heart [top]

Cardiac Muscle Cells

Short, branching cells with a single nucleus and light striations. Cardiac muscle cells are joined together at intercalated discs. Cushioned by endomysium and arranged in spiral bundles. [top]

Cardiac Output

The blood volume pumped out by the left ventricle of the heart measured in litres per minute [top]

Cardiac Sphincter

A muscular ring between the stomach and esophagus which stops food from coming back up the esophagus after it has been swallowed [top]

Cardiovascular System

Circulates gases, nutrients and wastes via the heart, blood vessels and circulatory fluid. The circulatory fluid in animals is blood and is pumped via the vascular system with the help of the heart (the pump). [top]

Cartilage (elastic)

Consists of chondrocytes and collagen fibers with a matrix that allows the cartilage to stretch. Ex. External ear, nose [top]

Cartilage (fibrocartilage)

Highly compressible tissue that consists of chondrocytes embedded in abundant collagen fibers. Ex. Vertebral discs [top]

Cartilage (hyaline)

Rubbery, blue-white tissue that consists of chondrocytes and abundant collagen fibers. Ex. Forms the larynx and covers the ends of bones at joints and ribs. [top]

Cartilaginous Rings

Rings of the trachea composed of hyaline cartilage. [top]

Catabolic

Something that induces destructive metabolism where complex substances are broken down into more simple substances [top]

Catabolism

Destructive metabolism where complex substances are broken down into more simple substances [top]

Catecholamines

A group of hormones and neurotransmitters that have similar effects on the sympathetic nervous system [top]

Cauda Equina

The bundle of spiral nerve roots which extend beyond the spinal cord below the first lumbar vertebra [top]

Cecum

A blind ending pouch at the beginning of the large intestine between the ilium and the colon [top]

Cells

The fundamental structural unit of living organisms; Composed of a cell membrane and several intracellular structures and molecules Ex. The cells of animals differ from bacterial cells because animal cells contain membrane-bound organelles and a nucleus [top]

Cell Body

The part of a nerve cell that contains the nuclus and cytoplasm [top]

Cell Cycle

Cycle controlling cell reproduction; consists of an S phase and M phase [top]

Cell Differentiation

A process where a less specialized cell becomes a specialiized cell type during embryogenesis. [top]

Cell Junction

Connections between cells that attach cells together, allow cells to communicate and create impenentrable barriers between different tissues and sections of the body. Ex. Tight junctions, desmosomes and gap junctions [top]

Cell-mediated Immunity

The recognition and destruction of antigens by T-cells during an immune response. [top]

Cell Membrane

Phospholipid bilayer surrounding cells containing a fluid mosaic of many embedded molecules (ie. glycolipids, cholesterol and proteins) [top]

Cell Transport

The movement of substances across the cell membrane. Substances such as water, ions and proteins cross the cell membrane in cell transport. [top]

Cellular Immunity

The response of T cells to infection, involving communication from helper T cells and the destruction of infected or cancerous cells by killer T cells. [top]

Cellular Respiration

The transfer of oxygen and carbon dioxide between cells [top]

Central Canal

A small canal running through the grey matter of the spinal cord which is continuous with the ventricles of the brain [top]

Central Nervous System (CNS)

Part of the nervous system that is comprised of the brain and spinal cord [top]

Cerebellum

A large area located at dorsal aspect of the brain that functions in equilibrium and muscle coordination [top]

Cerebrospinal Fluid (CSF)

Fluid that fills the cavities of the brain and spinal cord and surrounds them externally to provide protection [top]

Cervical

Relating to the neck [top]

Cervix

The narrow, lower end of the uterus where it joins with the vagina [top]

Chain Ganglia

A series of sypathetic ganglia lying parallel and lateral to the spinal cord. [top]

Chain of Infection

The chain of events in which a pathogen infects a host and spreads. [top]

Cheif Cells

Cells which release precursor enzymes. Ex, chief cells of the intestines secrete pepsinogens which activate and become pepsin. [top]

Chemical

A substance or compound with a distinct molecular composition that is obtained from or used in a chemical process [top]

Chemical Digestion

The breaking down (catabolism) of larger molecules into smaller chemical units [top]

Chemokines

Alarm chemicals released by injured cells that signal mast cells to release histamines and white blood cells to enter the injury site. Ex. White blood cells follow the concentration gradient of chemokines to locate an injury site. [top]

Chemoreceptor

A sensory receptor on an organ that responds to chemical stimuli. Ex, a taste bud on the tongue. [top]

Chemotaxis

Movement of a cell toward or away from a chemical stimulus. [top]

Cholecystokinin (CCK)

A hormone secreted by the mucosa of the duodenum that regulates enzyme secretion by the pancreas and emptying of the gallbladder [top]

Cholesterol

A steroid hormone precursor contained in cells and body fluids which regulates membrane fluidity and is normally synthesized by the liver [top]

Cholinergic

Involving or activated by acetylcholine [top]

Choroid Plexus

A vascular membrane within the pia mater which projects into the cerebral ventricals and secretes cerebrospinal fluid [top]

Chorion

The outer membrane of an embryo which contributes to the formation of the placenta. [top]

Churn

To stir or agitate [top]

Chyme

The mass of partially digested food that leaves the stomach and enters the small intestine [top]

Cilia

A short, hairlike appendage of some unicellular organisms that is involved in locomotion. [top]

Circle of Willis

A circular collection of arteries located at the base of the brain formed by cerebral and communicating arteries [top]

Circular (round) Window

A round opening on the medial wall of the inner ear leading to the cochlea. It is covered by a secondary tympanic membrane which compensates for pressure changes. [top]

Circumduction

body movement that combines flexion, extension, abduction and adduction to create circular motion of the distal part of the limb. This type of movement is common in ball-and-socket joints. Ex. You make small circular motions with your arm. [top]

Cisterna Chyli

The lymph channel which marks the opening to the thoracic duct located opposite the first and second lumbar vertebrae. [top]

Cleavage

Mitotic cell divisions which cause a single celled zygote to become a multicellular embryo [top]

Clitoris

A small erectile organ of the vulva in females that is similar to the penis in males [top]

Clonal Selection

A process where specific B and T lymphocytes are selected to respond to specific antigens. [top]

Clones

A group of genetically identical cells derived from a single parent cell. [top]

Clot

A mass of coagulated blood [top]

Coagulation Cascade

The cascade of events during the blood clotting process which leads to the formation of fibrin. [top]

Coccus

Bacteria with a round shape [top]

Cochlea

A portion of the bony labyrinth of the inner ear whose cavity extends to the petrous portion of the temporal bone containing nerves which are essential for hearing [top]

Cochlear Duct

A spiral tube within the cochlea [top]

Collagen

A fibrous protien contained in connective tissues such as bone, cartilage and tendons. [top]

Collateral Branches

Branches of an axon [top]

Collateral Ganglia

Sympathetic ganglia which lie between the sympathetic chain and the target organ [top]

Collecting Duct

The part of the nephron which collects urine from the distal convoluted tubule and passes it to the renal pelvis. [top]

Collecting Tubules

The part of the nephron which collects urine from the distal convoluted tubule and passes it to the renal pelvis. [top]

Colon (Large Intestine)

The lower part of the intestines composed of the cecum, colon and rectum where moisture is extracted and digested food is then excreted as feces [top]

Colony

A group of microorgansims growing on a solid nutrient medium. [top]

Columnar Epithelium

Elongated cells greater in height than width; often ciliated. Ex. Intestinal wall cells [top]

Common Hepatic Duct

Part of the biliary duct system and is formed by the junction of the right and left hepatic ducts. When joined with the cystic duct it becomes the common bile duct. [top]

Compact Bone

One of the two basic types of bone tissue. Smooth in appearance; continuous, dense bone tissue. Ex. Outer region of long bones is compact bone [top]

Complement Proteins

Proteins created by the liver and found in plasma which combine to form "membrane attack complexes" (MAC) capable of destroying target cells [top]

Complete (Fused) Tetanus

maximum force contraction of a whole muscle produced by a high frequency of stimulation and high recruitment [top]

Conchae

The shell shaped turbinate bones of the nose. The conchae form ridges that cause turbulence in the air entering the nasal cavity, which allows more air to contact the mucosa and trap particles in the air. [top]

Conditioned

A change so that a response that may have been associated with one stimulus, is now associated with another [top]

Conditioned (aquired) Reflexes

A response to a stimulus after conditioning has taken place [top]

Conditioned Salivary Reflex

A reflex involving sensory inputs such as emotion, thoughts or smells processed by the cerebral cortex. Signals are then sent from the cortex to the salivary centre in the medulla where motor signals are sent to increase salivary secretion. [top]

Cones (eye)

A cone shaped photosensitive receptor cell in the retina of the eye which functions to detect colour [top]

Conjugation

A process in which bacteria exchange DNA segments through a temporary structure called a pilus [top]

Connective Tissue

Tissue found between body parts and other types of tissue; functions in protection, support and physical connection between tissues. Composed of a cellular component and a non-living extracellular matrix. Ex. Cartilage, bone, adipose tissue [top]

Constant Regions (heavy chain)

A pair of polypeptide chains that are a subunit of an immunoglobulin and have a higher molecular weight. Heavy chains serve as the binding sites for antigens. [top]

Contractile Fibers

cytoskeletal elements that produce shortening during skeletal muscle contraction [top]

Contraction

Shortening; Muscles are specialized in contraction [top]

Contractions

Tightening of the uterine muscles in preparation for child birth; induced and strengthened by the hormone oxytocin [top]

Contralateral

On opposite sides of the body; opposite meaning to ipsilateral. Ex. The left eye is contralateral to the right ear [top]

Control Center

Determines the "set point" in a homeostatic control mechanism and regulates the body's response. Ex. The control center for most body processes is the brain [top]

Convert

To change into a different form or property [top]

Cornea

The transperent outer fibrous coat of the eye which covers the pupil and iris, is continuous with the sclera and admits light to the eye's interior [top]

Corona Radiata

Small follicular cells that surround the ovum in the follicle and remain attached during and after ovulation [top]

Corpus Luteum

Also known as a "yellow body", it is a small body that forms in the empty follicle after the release of the mature ovum. It secretes the hormone progesterone which maintains pregnancy but becomes inactive after 10-14 days if the ovum is not fertilized. At this point menstruation occurs. [top]

Cortex

The outer layer of a structure or organ [top]

Cranial

Pertaining to the skull or cranium [top]

Cranial Cavity

A dorsal cavity encompassing the inside of the head. Ex. The cranial cavity contains the brain [top]

Cranial Nerves

12 nerve pairs existing in the brain including the: olfactory nerve (I), optic nerve (II), oculomotor nerve (III), trochlear nerve (IV), trigeminal nerve (V), abducens nerve (VI), facial nerve (VII), vestibulocochlear nerve (VIII), glossopharyngeal nerve (IX), vagus nerve (X), accessory nerve (XI) and the hypoglossal nerve (XII) [top]

Cranial Nerve I (Olfactory Nerve)

Pair of cranial nerves which conduct nerve impulses from the mucous membranes of the nose to the brain [top]

Cranial Nerve VII (Facial Nerve)

The seventh pair of cranial nerves which supply the muscles of the face and jaw with motor nerve fibers. These nerve fibers control facial expression and the glands of the palate and taste buds in two thirds of the tongue. [top]

Cranial Nerve VIII (Vestibulocochlear Nerve)

The eighth pair of cranial nerves which innervate the membranous labyrinth of the inner ear and consist of the vestibular nerve and the cochlear nerve [top]

Cranial Nerve IX (Glossopharyngeal Nerve)

The ninth pair of cranial nerves that consist of motor fibers that supply the muscles of the pharynx, soft palate, posterior tongue and parotid glands. [top]

Cranial Nerve X (Vagus Nerve)

The tenth pair of cranial nerves that consist of motor fibers which supply the muscles of the the pharynx, larynx, heart and thoracic and abdominal viscera and sensory fibers that conduct nerve impulses from these areas to the brain. The vagus nerve functions to stimulate digestion and regulate heartbeat. [top]

Cranial Reflex

A reflex response that is carried out after a stimulus is received by the brain [top]

Craniosacral Division

Also known as the parasympathetic division of the peripheral nervous system because the nerves exit the central nervous system in the cranial and sacral regions of the spine. [top]

Creatine Phosphate

energy storage molecule found only in muscle containing a high-energy phosphate, which is transferred to ADP to supply energy for muscle contraction [top]

Cross Bridge Cycle

the alternate binding, movement and release of actin by myosin during muscle contraction [top]

Cuboidal Epithelium

Cube-shaped epithelial cells. Ex. Glands [top]

Cutaneous Membrane

Skin; Dry epithelial membrane covering the outer surface of the body. Consists of two layers: Epidermis and dermis [top]

Cutaneous Receptor

A type of receptor found in the dermis and epidermis that responds to sensory stimuli. [top]

Cyst

Dormant (inactive) form of a pathogen that is resistant to adverse conditions [top]

Cystic Duct

The duct exiting the gallbladder which joins with the hepatic duct to form the common bile duct [top]

Cytokines

Cellular proteins which are released by cells during an immune response and serve as communication signals [top]

Cytoskeleton

Filaments that provide support and movement for the cell with the aid of ATP and motor proteins [top]

Deep

Away from the body surface; opposite meaning to superficial. Ex. The bones are deeper than the skin [top]

Deep Pressure Receptor

Also know as Pancinian corpuscles; a type of sensory receptor found in the skin that is sensitve to vibration and pressure [top]

Defecation

To void feces from the rectum through the anus [top]

Delivery

The act of expulsion of a child through the birth canal during child birth [top]

Dendrite

The branching process of a neuron that sends impulses toward the cell body [top]

Dense Connective (fibrous) Tissue

Tissue consisting of fibroblasts and densely packed collagen fibers with very little matrix; elastic when in ligaments. Ex. Ligaments and tendons [top]

Dephosphorylated

has had a phosphate removed; Ex. When ATP is converted to ADP it is dephosphorylated [top]

Depolarize

Loss or reduction of negative membrane electrical potential [top]

Dermis

Basal layer of the cutaneous membrane composed of dense connective tissue. Areas containing large numbers of blood vessels in the dermis appear reddish [top]

Descending Colon

The part of the colon that descends along the left of the abdomen below the spleen and ends at the sigmoid colon [top]

Desmosomes

Cell junctions that anchor cells to one another to prevent tissues from being torn apart. Ex. Skin cells [top]

Detect

To perceive or notice [top]

Detergent Action

Emulsification of fats by isolating small fat droplets from each other [top]

Diapedesis

The movement of blood cells through capillaries to surrounding body tissues. [top]

Diaphragm

The muscular partition that separates the abdominal cavity from the thoracic cavity and assists in respiration through contraction and relaxation [top]

Diaphysis

The shaft of a long bone. Contains the medullary cavity and bone marrow and makes up most of the length of a long bone. [top]

Diastole

The passive dilation of the heart where the chambers fill with blood. [top]

Diastolic

The minimum blood pressure measured during the period of the heart beat where the ventricles and atria relax to allow the chambers to fill with blood. [top]

Differentiating

In cell biology; the period during which cells become specialized to form a specific cell type [top]

Digestive System

Responsible for the ingestion and breakdown of food to extract nutrients; Elimination of wastes. The mouth, esophagus, stomach and intestines form the major parts of the digestive system. [top]

Dilation

The stretching or enlarging of an organ or body part. Ex, dilation of the cervix during child birth [top]

Diploid Zygote

A cell formed from combining two haploid gametes (spermatozoa and ovum) containing 46 chromasomes which will implant on the uterine wall of a female and develop into a fetus. [top]

Direct Contact

Contraction of a pathogen through another infected host by skin contact, sneezing, coughing, or bites from a vector such as a tick. [top]

Direct Phosphorylation

phosphorylation of ADP to ATP by creatine phosphate (CP); provides approximately 15 seconds of energy during muscle contraction [top]

Disaccharide

Any type of sugar that is composed of two monosaccharides [top]

Distal

Away from the point of origin; opposite meaning to proximal. Ex. The toes are distal to the ankles [top]

Distal Convoluted Tubule (DCT)

The part of the nephron located between the loop of Henle and the collecting duct. This is where urine becomes concentrated. [top]

Division

A separated group [top]

Dorsal

Situated toward the back [top]

Dorsal Columns

A column of white matter in the dorsal aspect of the spinal cord where fine touch receptors are located [top]

Dorsal Horns

The dorsal section of grey matter in the spinal cord where sensory receptors are contained [top]

Dorsal Root Ganglions

A nodule on a dorsal root containing cell bodies of afferent neurons [top]

Duct

A tube or vessel that carries secretions from exocrine glands [top]

Duct Cells

Cells of the pancreas that secrete bicarbonate ions to neutralize chyme in the duodenum. [top]

Ductless (endocrine) Glands

Any gland that secretes hormones directly into the blood stream. These glands include the pituitary, pineal, thyroid, parathyroid, adrenal, testes, ovaries and the islets of Langerhans of the pancreas [top]

Duodenum

The first portion of the small intestine exiting the stomach [top]

Dural Venous Sinuses

Vein channels found between the layers of dura mater in the brain which receive blood and cerebrospinal fluid [top]

Dura Mater

A fibrous membrane that makes up the outermost covering of the brain and spinal cord [top]

Ear

The organ of hearing and equilibrium which consists of an external ear, a middle ear and a fluid filled inner ear. The ear gathers sound vibrations and conducts them to the auditory nerve which sends impulses to the brain. [top]

Ectoderm

The outer of the three germ layers of the embryo which will form the epidermis, nervous tissue and sense organs. [top]

Edema

An abnormal accumulation of serous fluid in body tissues. [top]

Effector

Cells, tissues or organs that carry out a body's response to a stimulus as directed by the control center. Ex. When you put your hand on a hot stove, the effectors (your arm muscles) retract your hand [top]

Effector B cells (plasma cells)

An antibody secreting cell derived from B cells [top]

Efferent Cranial Nerve

A nerve that originates in the brain and transmitts impulses from the central nervous system to the peripheral nervous system [top]

Efferent (motor) Division

Portion of the peripheral nervous system consisting of efferent nerves that send motor output information from the integration centers in the brain and spinal cord to effector organs to carry out behavioural and physiological responses. [top]

Efferent Lymphatic Vessels

Lymphatic vessels which carry lymph away from the lymph node. [top]

Efferent Spinal Nerve

A nerve that originates in the spinal cord and transmitts impulses from the central nervous system to the peripheral nervous system [top]

Ejaculatory Duct

A duct formed by the junction of the deferent duct and the excretory duct from the seminal vesicle that conveys semen into the prostatic urethra [top]

Elastic Cartilage

Consists of chondrocytes and collagen fibers with a matrix that allows the cartilage to stretch Ex. External ear, nose [top]

Elastic Fibers

Fibers of the respiratory membrane which can stretch up to 1.5 times their length and then snap back to their original size to aid in expiration. [top]

Elastic Lamina

The elastic tissue that formes the outer layer of the tunica intima of blood vessels [top]

Electrical Signal

A signal that crosses a synapse that contains electrical current causing voltage changes in the postsynaptic neuron [top]

Electron Transport Chain

A process that occurs across the mitochondrial membrane where energy from reduction-oxidation reactions is used to produce large amounts of ATP [top]

Embryo

A developing human in the womb from the time of implantation in the uterus to the eighth week of conception [top]

Emulsify

To convert from a solid to a liquid; in digestion, to break large lipid droplets into smaller droplets [top]

Endocardium

The innermost of the three layers of the walls of the heart. [top]

Endocrine

Ductless secretion into the blood or lymph [top]

Endocrine (ductless) Glands

Any gland that secretes hormones directly into the blood stream. These glands include the pituitary, pineal, thyroid, parathyroid, adrenal, testes, ovaries and the islets of Langerhans of the pancreas. [top]

Endocrine System

Chemical signaling system consisting of glands that secrete hormones. Hormones regulate body processes and metabolic activities. Ex. The adrenal glands are organs of the endocrine system [top]

Endocytosis

Active transport in which materials in the extracellular fluid are engulfed by a vesicle, which then empties its contents in the intracellular fluid. Phagocytosis and pinocytosis are both types of endocytosis. [top]

Endocytosis (receptor-mediated)

Type of endocytosis in which specialized surface receptors bind with a specific molecule type in the extracellular space. A vesicle then forms around the complexes of receptor and molecules, taking in only the molecules bound to the receptors. Ex. Cholesterol enters cells by receptor-mediated endocytosis [top]

Endoderm

The inner of the three germ layers of the embryo which will form the epithelium of the digestive and respiratory tract [top]

Endolymph

The watery fluid within the membranous labyrinth of the inner ear [top]

Endometrium

A mucous membrane lining the interior of the uterus [top]

Endomysium

thin connective tissue wrapping individual muscle cells [top]

Endothelial

A thin layer of epithelial cells which line lymph vessels. [top]

Enteric Nervous System

Also known as the intrinsic nerve plexus; A nerve plexus of the digestive system which functions independently from the central nervous system and controls digestive function in response to stimuli inside the digestive tract. [top]

Enzymes

Complex proteins produced by cells that function as catalysts for biochemical reactions in the body [top]

Epidermis

Apical layer of the cutaneous membrane composed of stratified squamous epithelium. Keratinocytes produce keratin in the upper layers, while cells in the basal layer reproduce quickly to replace cells in the upper layers. [top]

Epididymis

An organ comprised of ductules that is attached posteriorly to the testes, holds sperm during maturation and is continuous with the vas deferens [top]

Epigastric Cavity

Abdominopelvic region superior to the umbilical region and medial to the hypochondriac regions [top]

Epimysium

fibrous connective tissue wrapping surrounding a muscle [top]

Epiphyseal Line

The remnant of the epiphyseal plate where long bone growth occurred before the onset of puberty. In adulthood, the epiphyseal plate is composed entirely of bone tissue and can no longer grow. [top]

Epiphyseal Plate

Region between the epiphysis and diaphysis of a long bone where bone growth occurs before the end of puberty. [top]

Epiphysis

The end (head) of a long bone composed of a thin layer of compact bone enclosing spongy bone; Covered in a layer of articular cartilage that decreases friction at joints. Ex. proximal and distal epiphysis [top]

Epithelial Tissue

Continuous sheets of cells that create body linings, coverings and glands; functions in protection, absorption, filtration and secretion. Has a free apical surface and an attached basal surface. Ex. Lining of the digestive tract [top]

Equilibrium

Balance between opposing forces [top]

Erectile Tissue

Tissue composed of many cavernous blood vessels which can become engorged with blood [top]

Erection

When a previously flaccid body part containing cavernous blood vessels becomes engorged with blood and as a result becomes firm and enlarged [top]

Erythrocytes (Red Blood Cells)

Cells of blood that have no nucleus but contain hemoglobin which gives blood its red colour and functions to carry oxygen to the tissues. [top]

Erythropoietin

A hormone which stimulates the creation of red blood cells and hemoglobin in the bone marrow in response to low oxygen levels in the tissues [top]

Esophageal Stage

The stage of swallowing where chewed up food is passed throught the esophagus from the pharynx to the stomach [top]

Esophagus

The muscular, tubular structure of the alimentary canal which connects the pharynx with the stomach [top]

Essential Amino Acid

An amino acid that is required for growth but cannot be synthesized by cells and therefore must be supplied in the diet [top]

Estrogen

Hormones released by the ovaries which stimulate the development of secondary sex characteristics and development and maintenance of the reproductive system in females [top]

Ethmoid Bone

The spongy bone of the skull that makes up the septum of the nasal cavity and contains olfactory nerve fibers [top]

Eupnea

Normal and easy respiration [top]

Excitatory

To excite an action or impulse [top]

Excretion

The elimination of a substance, such as urine or sweat, from the body [top]

Exocrine

Relating to a secretion released through a duct externally [top]

Exocrine Glands

A gland such as a sweat gland or salivary gland that releases secretions through a duct to a body part that connects to the external environment. [top]

Exocytosis

Active transport in which materials in the intracellular fluid are engulfed by a vesicle, which then secretes its contents into the extracellular fluid. Ex. Cells that are specialized in secretion (such as glands) use exocytosis frequently [top]

Expiration

The exhalation of carbon dioxide out of the lungs [top]

Extension

body movement that increases the angle of a joint and brings to bones further apart, and is the opposite movement to flexion. Extension commonly occurs in the sagittal plane Ex. You straighten your leg at the knee such that your foot is lowered into a standing position. [top]

Externa

The outermost layer of an organ [top]

External Acoustic Meatus

A tubular structure running from the exterior to the middle ear. Also known as the ear canal. [top]

External Intercostal Muscles

Outer layer of intercostal muscles; contract during inspiration and relax during passive expiration [top]

External Respiration

The exchange of oxygen and carbon dioxide between the lungs and external environment [top]

External Urethral Oriface (opening)

The external opening of the urethra in the glans penis in males and the vestibule in females [top]

External Urethral Sphincter

The spincter muscle located at the junction of the urethra and external urethral oriface that voluntarily relaxes so that micturition may occur. [top]

Extracellular

Outside the cell; external to the plasma membrane. Ex. The plasma is extracellular to the red blood cells in blood [top]

Extracellular (interstitial) fluid (ECF)

Water-based solution found surrounding cells containing gases, nutrients, regulatory chemicals, salts and waste products [top]

Extrinsic Nerves

Nerves making contact with the digestive system that originate from outside the digestive system [top]

Extrinsic Nerve Plexus

A nerve plexus of the digestive system that works in conjunction with the central nervous system and the autonomic nervous system to control emotion and information about food. [top]

Facial Nerve (Cranial Nerve VII)

The seventh pair of cranial nerves which supply the muscles of the face and jaw with motor nerve fibers. These nerve fibers control facial expression and the glands of the palate and taste buds in two thirds of the tongue. [top]

Facilitated Diffusion

The passive movement of solutes from an area of higher concentration to an area of lower concentration through a membrane channel protein or with the aid of a transport protein. Larger molecules that cannot move across the cell membrane by simple diffusion often require facilitated diffusion or active transport. [top]

Falling Phase

A phase in action potential generation. During this phase, repolarization takes place by potassium ions diffusing out of the cell through K+ ion channels causing the membrane levels to decline to a resting state. [top]

False Labour

Irregular uterine muscle contractions that occur during pregnancy without dilation of the cervix [top]

Fascicle

bundle of muscle cells or nerve cells wrapped in connective tissue [top]

Fenestration

Holes that allow through large molecules; large proteins and cells cannot pass through [top]

Fertilization

The union of the two gametes (ovum and spermatozoon) to form a zygote and initiate the development of a new individual [top]

Fetal Circulation

The system of structures and blood vessles which carry blood through a fetus and to and from the placenta. [top]

Fiber

A threadlike structure [top]

Fibrin

A fibrous protein which is created by fibrinogen during the blood clotting process and is responsible for producing an interlaced, fibrous network where cells become trapped and form a blood clot. [top]

Fibrinogen

A plasma protein which is converted to fibrin by thrombin to facilitate blood clotting. [top]

Fibrocartilage

Highly compressible tissue that consists of chondrocytes embedded in abundant collagen fibers. Ex. Vertebral discs [top]

Fibrosis

Scar tissue; dense connective tissue which forms underneath a healed wound [top]

Fibrous Pericardium

The outer layer of the pericardium composed of connective tissue which anchors the heart to the surrounding body walls, protects it and prevents it from over filling [top]

Fight or Flight

Pertaining to a response to stress from the sympathetic nervous system which includes exercise and activity. Ex, A prey animal will run away from a predator through activation of the sympathetic nervous system. [top]

Filtrate

A fluid that has been passed through a filter. Ex, urine after it has passed through the filtration slits in the Bowman's capsule [top]

Filtration

Special type of cell transport in which a fluid (the filtrate) is forced across the cell membrane due to fluid pressure. The filtrate contains both solute and solvent, and only large molecules and cells are not contained in the filtrate. Ex. Nephrons in the kidneys specialize in filtration [top]

Filtration Slits

Pores in podocytes that allow only water and small molecules to pass into the Bowman's capsule. [top]

Fimbriae

A fringe of tissue located near the ovary that acts as a sweeper to transport the ovum from the ovary to the fallopian tube [top]

Flagella

A long, hairlike appendage of some unicellular organisms that is involved in locomotion. [top]

Flat Bone

Shape classification of bone; Thin compact bone surrounding a layer of spongy bone shaped into a very thin, plate-like structure. Flat bone are often curved to fit around internal structures. Ex. skull, ribs, sternum [top]

Flexion

body movement that decreases the angle of a joint and brings two bones closer together. Common in hinge and ball-and-socket joints, and opposite to extension. Flexion commonly occurs in the sagittal plane. Ex. You bend your leg at the knee such that your foot is raised behind you [top]

Follicle

Small sacs which develop on the ovary and contain an immature ovum [top]

Follicle-Stimulating Hormone (FSH)

A hormone secreted by the anterior pituitary gland which stimulates the growth of ovarian follicles containing ovum [top]

Follicular Phase

The phase of the menstrual cycle where the ovarian follicle develops [top]

Fomite

An inanimate object, such as a door knob, that may carry an infectious agent [top]

Foramen

An opening or passege in bone. Ex, the foramen magnum is an opening in the base of the skull [top]

Foramen Magnum

A large opening at the dorsal base of the skull connecting the cranial cavity to the spinal canal [top]

Foramina

Openings or passeges in bone. Ex, the foramen magnum is an opening in the base of the skull [top]

Foreskin

A fold of skin on the penis which covers the glans and is retractable [top]

Frequency

the number of occurrences in a given period of time [top]

Frontal Plane

Plane dividing the anterior from posterior body; the plane extends vertically through the left-right axis of the body [top]

Function

to perform a specific action or activity [top]

Fundus

The upper portion of the stomach where undigested food is stored [top]

Fungi

A single celled microorganism which lives by decomposing the organic material on which it grows. Ex, mold. [top]

Fungiform Papillae

Mushroom shaped projections on the tongue which contain taste buds [top]

Fused (Complete) Tetanus

maximum force contraction of a whole muscle produced by a high frequency of stimulation and high recruitment [top]

Fusiform

Cylindrical shape tapered at both ends. Ex. Smooth muscle cells are fusiform [top]

Gallbladder

A small muscular sac located in the right lobe of the liver which functions to store and secrete bile into the duodenum [top]

Ganglion

A mass or collection of nerve cell bodies existing outside of the brain and spinal cord (CNS) [top]

Gap Junctions

Cell junctions that directly connect cells together for electrical and chemical communication. Protein cylinders come together in connexons to create the connection Ex. Neurons [top]

Gas Exchange

The exchange of oxygen and carbon dioxide in the lungs during respiration [top]

Gastric Juices

Fluids and enzymes secreted by the glands of the stomach that aid in digestion including hydrochloric acid and pepsin [top]

Gastrin

A hormone secreted by the stomach to stimulate the secretion of gastric juices [top]

Gastrointestinal (GI) Tract

The part of the digestive system consisting of the stomach, small intestine and large intestine [top]

Gastrula Stage

Stage during embryonic development when the embryo develops the primordial germ layers (ectoderm, mesoderm and endoderm). The primitive gut cavity forms during gastrulation. [top]

Germinal Centers

The site of B-lymphocyte proliferation, differentiation and mutation within a lymph node. [top]

Gland

A cell or organ which produces a secretion [top]

Glandular Epithelium

Produces endocrine or exocrine secretions manufactured from blood components. Ex. Adrenal glands [top]

Glans

A small, round glandlike mass. Ex, head of the penis or head of the clitoris [top]

Glomerular Filtration Rate (GFR)

The volume of water filtered through the glomerulus into the Bowman's capsule per unit of time. [top]

Glomerulus

A network of capillaries located at the origin of the nephron where filtrate is passed from the blood to the Bowman's capsule. [top]

Glossopharyngeal Nerve (Cranial Nerve IX)

The ninth pair of cranial nerves that consist of motor fibers that supply the muscles of the pharynx, soft palate, posterior tongue and parotid glands. [top]

Glucagon

A hormone secreted by the pancreas that acts as an opposition to insulin in order to regulate blood glucose levels. Glucagon is a hyperglycemic hormone (increases blood glucose concentration). [top]

Glucocorticoids

A group of corticosteroids secreted by the adrenal cortex that function in carbohydrate, protein and fat metabolism and are used as anti-inflammatory agents [top]

Glucose Release

Glucose is released from cells and into the bloodstream [top]

Glycogen Breakdown

The conversion of glycogen to glucose stimulated by the hormones glucagon and epinepherine. [top]

Glycolysis

The catabolism of carbohydrates glucose or glycogen into pyruvic and lactic acid [top]

Golgi Apparatus

Modifies cell products from other organelles and tags them for export. Forms lysosomes and secretory vesicles. [top]

Gonadotropin Releasing Hormone (GnRH)

A hormone produced by the hypothalamus which stimulates the anterior pituitary gland to secrete leutinizing hormone and follicle stimulating hormone [top]

Gonads

A sex gland that produces gametes. Ex, testis and ovaries [top]

Graded Response

response regulated in small increments; opposite to an all-or-nothing response [top]

Gram Stain

A staining technique used to classify bacteria as either Gram positive or Gram negative. Bacteria are first stained with gentian violet and then with Gram's solution. The bacteria are then decolourized with alcohol, washed with water and treated with Safranine. If the bacteria retain their violet colour when the process is complete they are considered Gram positive. If the bacteria show a pink colour they are considered Gram negative. [top]

Granular Cells

Cells of the afferent arteriole which sense low blood pressure and secrete renin into the blood. [top]

Granulation Tissue

Delicate pink tissue rich in capillaries that forms underneath a scab during wound healing. Contains fibroblasts, which begin to fill the injury site with collagen fibers. [top]

Granules

Cytoplasmic particles found in some blood cells [top]

Granzymes

Enzymes secreted by cytotoxic T cells and natural killer cells to induce apoptosis within virus infected cells. [top]

Grey Matter

Reddish-gray nerve tissue found in the brain and spinal cord that contains nerve cell bodies [top]

Growth Hormone

A hormone secreted by the anterior pituitary gland that functions to stimulate lactation by the mammary glands at parturition [top]

Gustatory

Relating to the sense of taste [top]

Gustatory Area

A portion of the brain which receives sensory information for taste [top]

H+

Hydrogen ion [top]

Hair Cells

A hairlike sensory cell contained in the epithelium of the organ of Corti in the inner ear [top]

Haploid Gametes

A cell containing 23 chromasomes, such as a spermatozoa or ovum, which will fuse with another cell to form a diploid zygote. [top]

Haptens

A small section of an antigen that reacts with an antibody but cannot stimulate antibody production without being bound to a carrier protein molecule. [top]

Haustra

Small pouches of the colon which give it its segmented appearance [top]

Haustral Churning

Slow, rhythmic movements of the haustra of the colon in order to mix the forming feces and recover water from it. [top]

Hearing

A special sense where sound is perceived through the organ of Corti in the ear and transmitted to the brain via the auditory nerve [top]

Heart

A hollow, muscular organ located in the thoracic cavity of humans that acts as a pump to maintain blood circulation and pressure throughout the body. [top]

Hematopoiesis

The formation of blood cells [top]

Hemoglobin

The red pigment found in red blood cells which functions to carry oxygen to tissues. [top]

Hemostasis (Blood Clotting Response)

The stoppage of bleeding or hemorrhage [top]

Hepatic Artery

A branch of the celiac artery which supplies the liver with oxygenated blood [top]

Hepatic Ducts

A pair of ducts which carry bile from the liver to the common hepatic duct which is joined by the cystic duct from the gallbaladder to form the bile duct. [top]

Hepatic Lobules

Hexagonal tissue segments of the liver. [top]

Hepatic Portal System

A group of veins that take blood from the capillaries of the pancreas, spleen, stomach and intestine and transport it to the sinusoids of the liver [top]

Hepatic Portal Vein

A vein that transports blood from the capillaries of the pancreas, spleen, stomach and intestine and transports it to the sinusoids of the liver so it can be altered by hepatocytes before systemic circulation [top]

Hepatic Vein

Any of three veins which carry blood from the liver to the inferior vena cava just below the diaphragm [top]

Hepatocyte

A liver cell [top]

Hepatopancreatic Duct

A duct connecting the pancreas to the common bile duct supplying the duodenum with pancreatic juices and bile which aid in digestion. [top]

Hepatopancreatic Sphincter

A muscular valve which directs digestive juices into the duodenum and prevents back flow into the the pancreas and gallbladder. [top]

High

A large amount [top]

High-density Lipoproteins (HDL)

A plasma protein which transports cholesterol from body cells to the liver for disposal [top]

High Pressure

Force that is greater than normal [top]

Histamine

Chemical released by mast cells which causes vasodilation and increases capillary permeability [top]

Homeostasis

The maintenance of a steady internal state despite changes in external conditions. Ex. Humans must maintain a body temperature of approximately 37 degrees Celsius for proper homeostasis [top]

Homeostatic Control Mechanisms

Mechanisms for maintaining survival needs within an acceptable range. Ex. If the homeostatic control mechanism for body temperature were not working properly in an individual, that individual would not be able to stay at an appropriate body temperature [top]

Hormones

Chemical substances produced by endocrine glands which are secreted into the blood and transported to specific organs to stimulate their function. Ex, estrogen, adrenaline. [top]

Hormone-receptor Complex

When a hormone binds to its individual receptor inside a cell it becomes a hormone-receptor complex which can then enter the cell's nucleus through nuclear pores and alter genetic material. [top]

Host

Provides support for the growth of a microbe [top]

Human Chorionic Gonadotropin (hCG)

A hormone secreted by the placenta during early pregnancy to maintain corpus luteum function. It is found in the urine and blood of pregnant females and is often tested for to indicate pregnancy. [top]

Humoral Immune Response

An immune response that is mediated by the transformation of B cells into plasma cells which produce antibodies for specific antigens and respond to them after renewed exposure. [top]

Humoral Immunity

The transformation of B cells into plasma cells which produce antibodies for specific antigens and respond to them after renewed exposure. [top]

Hyaline Cartilage

Rubbery, blue-white tissue that consists of chondrocytes and abundant collagen fibers Ex. Forms the larynx and covers the ends of bones at joints and ribs. [top]

Hydrochloric Acid

An acidic solution that is diluted in gastric juice [top]

Hydrolases

Enzymes found in the mouth, stomach and intestines which help break down ingested materials. [top]

Hydrolysis

The chemical breakdown of ingested materials into units small enough to be absorbed. [top]

Hydrophilic

Readily combining with or dissolving in water [top]

Hydrophobic

Repelling or unable to dissolve in water [top]

Hyperextension

extension where the joint angle exceeds 180 degrees. [top]

Hyperglycemic Hormones

Hormones, such as glycogen, which are released to raise blood glucose levels when they drop to dangerously low levels. [top]

Hyperpnea

An abnormal increase in respiratory rate [top]

Hypochondriac Region

Abdominopelvic region lateral to the epigastric region; divided into left and right hypochondriac regions [top]

Hypodermis

Subcutaneous tissue consisting mostly of adipose (fatty) tissue. Anchors the skin to underlying tissues. [top]

Hypogastric Region

Abdominopelvic region inferior to the umbilical region, medial to the iliac regions and inferior to the umbilical region [top]

Hypoglycemic Hormone

Hormones, such as insulin, which are released to lower blood glucose levels when they are at dangerously high levels. [top]

Hypophysis (Pituitary Gland)

A paired endocrine gland attached to the base of the brain that is separated into anterior and posterior sections and secretes growth hormone, LH, FSH, ACTH, TSH, ADH, PRL and oxytocin. [top]

Hypothalamic Pituitary Stalk

The point of connection of the pituitary gland to the hypothalamus. [top]

Hypothalamic-hypophyseal Portal System

A system of blood vessels which travel between the hypothalamus and anterior pituitary gland and allows for endocrine communication between them. [top]

Hypothalamus

A section of the brain located between the thalamus and midbrain that functions to control the autonomic nervous system which regulates sleep cycles, body temperature and appetite. The hypothalamus also releases hormones which control the hormonal secretions of the pituitary gland. [top]

I band

region of a sarcomere where only actin filaments are found; corresponds to the lighter stripes of striated muscle [top]

IgG

Immunoglobulin G; a class of immunoglobulins that are found in circulating blood and can be passed across the placenta from the mother to the fetus. [top]

Ileocecal Valve

A muscular sphincter located at the junction of the ileum and the large intestine functioning to prevent the contents of the large intestine from backing up into the small intestine. [top]

Ileum

The lower portion of the small intestine located between the jejunum of the small intestine and the cecum of the large intestine [top]

Iliac Region

Abdominopelvic region lateral to the hypogastric region; divided into left and right iliac regions [top]

Immunity

Resistance to infection by a specific pathogenic microbe. [top]

Immunocompetent

Having a normal capacity to produce an immune response; in lymphocytes, mature lymphocytes having gained antigen receptors that give them the ability to recognize a specific antigen. [top]

Immunoglobulins (Igs)

Proteins found in plasma cells that act as antibodies in an immune response. [top]

Immunological Memory

The capacity of the immune system to remember an antigen by activating memory B and T cells that will allow the immune system to respond more quickly on re-infection by the same pathogen. [top]

Implantation

The attachment of an embryo to the uterine wall. [top]

Incomplete Tetanus

whole muscle contraction in which tension is produced without pause, but small periods of relaxation are seen [top]

Incus

The central bone of the three ossicles of the middle ear [top]

Indirect Contact

Contraction of a pathogen through fomites or contaminated food or water. [top]

Infection

Invasion and multiplication of pathogenic microbes in the body causing disease. [top]

Inferior

Towards the feet; down; opposite meaning to superior. Ex. The foot is inferior to the knee [top]

Inflammatory Response

Swelling; a response to injury or pathogenic invasion that results in fluid buildup due to increased permeability of capillaries in the area [top]

Ingestion

To take food or drink into the body via the mouth [top]

Inhibition

The process of stopping or suppressing something [top]

Inhibitory

To inhibit an action or impulse [top]

Initiate

To begin or start [top]

Initiation Phase

A phase in action potential generation. During this phase, neurons are stimulated by neurotransmitters causing their cell membane to begin to depolarize [top]

Innate Defenses

Body defenses which defend the host from infection by responding to pathogens in a generic way; they do not adapt and they do not provide long-lasting immunity to the host. [top]

Inner Cell Mass

The mass of the blastocyst where the body of the embryo is formed. [top]

Insertion

attachment of a skeletal muscle to the more movable bone; during contraction, the origin moves towards the insertion [top]

Inspiration

The inhalation of air into the lungs [top]

Inspiratory Muscles

Muscles used in inspiration; external intercostal muscles and diaphragm [top]

Insulin

A hormone secreted by the beta islets of the islets of Langerhans in the pancreas which functions to regulate the metabolism of glucose. Insulin is the body's only hypoglycemic hormone and lowers blood glucose levels. [top]

Integration

combining parts to make a unified whole. Ex, interpreting multiple pieces of sensory information to make a single response. [top]

Integration Centers

A portion of the central nervous system that is responsible for interpretation of sensory information and decision making [top]

Integumentary System

Body coverings that protect the outside of the organism and deeper tissues. Contains receptors, sweat and oil glands. Produces Vitamin D. The skin is a part of the integumentary system. [top]

Intercellular Clefts

Small gaps between endothelilal cells that allow small molecules of any type to pass through [top]

Intercostal Nerve

The ventral divisions of any of eleven thoracic nerves [top]

Interferon

Chemical warning signals produced by virus-infected cells that trigger anti-viral defenses in healthy cells [top]

Intermediate

Between two structures. Ex. The elbow is intermediate to the shoulder and wrist [top]

Internal Anal Sphincter

An internal circle of smooth muscle around the rectum [top]

Internal Intercostal Muscles

Inner layer of intercostal muscles; contract during active expiration [top]

Internal Respiration

The exchange of oxygen and carbon dioxide between the cells of the body and the blood [top]

Internal Urethral Sphincter

The spincter muscle located at the junction of the bladder and the urethra that involuntarily relaxes so that micturition may occur. [top]

Interneurons (associaton neurons)

A nerve cell found within the brain or spinal cord (CNS) that links sensory (afferent) neurons to motor (efferent) neurons [top]

Interstitial Cells

Cells of the testes in males which are responsible for producing androgens [top]

Interstitial Fluid

Water-based solution found surrounding cells containing gases, nutrients, regulatory chemicals, salts and waste products [top]

Intima

The innermost layer of an organ [top]

Intracellular

Inside the cell; contained within the plasma membrane. Ex. The nucleus is found in the intracellular space [top]

Intracellular Fluid (ICF)

Water-based solution found inside cells containing gases, nutrients and salts all in small amounts. Includes the nucleoplasm and cytosol. [top]

Intracellular Receptor Protein

Proteins located within the cell instead of on the membrane which act as steroid and intracrine peptide hormone receptors. [top]

Intrinsic Factor

A substance secreted by the stomach that facilitates the absorption of vitamin B12 by the small intestine [top]

Intrinsic Nerve Plexus

A nerve plexus of the digestive system which functions independently from the central nervous system and controls digestive function in response to stimuli inside the digestive tract. [top]

Ipsilateral

On the same side of the body; opposite meaning to contralateral. Ex. The right leg is ipsilateral to the right ear [top]

Iron

A metallic element that is found in hemoglobin and allows red blood cells to carry oxygen to tissues [top]

Irregular Bone

Shape classification of bone; Bones that do not fit into the category of long, short or flat bones, often sharing the characteristics of multiple shape categories. Ex. vertebrae, hip bones [top]

Islets of Langerhans

Endocrine cells located in the tissue of the pancreas that secrete insulin and glucagon [top]

Jejunum

The middle portion of the small intestine located between the duodenum and the ileum [top]

Juxtaglomerular Apparatus (JG apparatus)

A unit of the kidney located near the glomerulus that controls the release of renin. [top]

K+ channels

Ion channels that form potassium selective pores in cell membranes to allow potassium ions to pass through [top]

Kidney

Either of the pair of bean shaped organs lying in the dorsal region of the abdominal cavity. These organs function to filter waste products out of the blood to produce urine and maintain electrolyte and acid-base balance. [top]

Krebs Cycle

A series of biochemical reactions where oxygen is converted into carbon dioxide and water when energy is released into the tissues through the breakdown of foods. [top]

Kupffer Cells

Macrophages of the liver that function to remove dead red blood cells and bacteria from the blood. [top]

Labia Majora

The outer folds of skin of the vulva on either side of the vaginal opening [top]

Labour

The process of child birth [top]

Lactic Acid Fermentation

conversion of pyruvic acid (a product of glycolysis) to lactic acid resulting from insufficient oxygen to carry out aerobic respiration [top]

Lactiferous Ducts

Ducts which carry milk from the mammary gland to the tip of the nipple. [top]

Large Intestine (Colon)

The lower part of the intestines composed of the cecum, colon and rectum where moisture is extracted and digested food is then excreted as feces

Lateral

Away from the midline; opposite meaning to medial. Ex. The shoulders are lateral to the head [top]

Lateral Columns

A column of grey matter in the center of the spinal cord [top]

Least Permeable

Least likely to be penetrated by molecules or substances [top]

Lecithin

A fatty substance that helps bile salts to emulsify fats during digestion [top]

Left Ventricle

A chamber on the left side of the heart which receives blood from the left atrium and pumps it into the aorta [top]

Lens

A biconvex body in the eye that lies directly behind the pupil and functions to focus light onto the retina [top]

Leukocytes (White Blood Cells)

Cells of the blood that are colourless, contain a nucleus and function to help the body fight infection and disease. [top]

Leukocytosis

An abnormal increase in the number of circulating white blood cells in the body [top]

Leukopenia

An abnormal decrease in the number of circulating white blood cells in the body [top]

Light Touch Receptors

A receptor found in the dorsal horn of the spinal cord where light touch is detected [top]

Limbic System

A group of structures in the brain, including the hypothalamus, hippocampus and amygdala, that are concerned with emotion and motivation [top]

Lingual Papillae

Projections on the tongue which do not contain taste buds and do not have any function in gustation [top]

Lipophilic

Readily dissolved or absorbed into lipids [top]

Liver

A large glandular organ located in the abdominal cavity below the diaphragm that secretes bile and functions in biotransformation of blood proteins and metabolism of carbohydrates, fats and proteins [top]

Local Depolarization

Loss or reduction of negative membrane electrical potential in one specific area of the cell membrane [top]

Localize

An infection that is restricted to one area of the body. [top]

Location

A place or position [top]

Long Bone

Shape classification of bone; Mostly compact bone with some spongy bone shaped into a long shaft with heads at both ends. Ex. Structural support for the limbs, excluding the knee caps (patella), wrist and ankle bones. [top]

Long Reflexes

Reflexes controlled by the central and autonomic nervous systems that are involved with emotion and information about food. [top]

Long Term

A long period of time [top]

Loop of Henle

The U shaped part of the nephron between the proximal and distal convoluted tubules where water and sodium reabsorption from the filtrate occurs. [top]

Loose Adipose Connective Tissue

fatty tissue; consists of adipose cells which store fat droplets and very little matrix. Ex. Found in subcutaneous region, surrounding some organs and in some deposits in the body [top]

Loose Areolar Connective Tissue

Fluid, spongy tissue that can retain excess fluid during swelling; consists of fibroblasts and a loose network of fibers. Ex. Mucous membranes, wrapping body organs [top]

Loose Connective Tissue

A type of tissue which acts to hold organs in place and surrounds blood vessels and nerves. There are three types: loose areolar connective tissue, loose reticular connective tissue, and loose adipose connective tissue. [top]

Loose Reticular Connective Tissue

Tissue consisting of reticular cells and delicate reticular fibers in a fluid matrix. Ex. Forms the stroma in lymphoid organs. [top]

Low

A small amount [top]

Low-Density Lipoproteins (LDL)

A plasma protein which transports cholesterol to body cells [top]

Low Pressure

Force that is less than normal [top]

Lower GI Tract

The portion of the gastrointestinal tract that is made up of the small intestine and large intestine and is responsible for chemical digestion, absorption and defecation. [top]

Lumbar

Relating to the abdominal region or the vertebrae lying between the thoracic vertebrae and the sacrum [top]

Lumbar Region

Abdominopelvic region lateral to the umbilical region; divided into left and right lumbar regions [top]

Lumen

The inner cavity of a hollow or tubular organ [top]

Lungs

The pair of organs located in the thoracic cavity that function to exchange oxygen with carbon dioxide during respiration [top]

Luteal Phase

The 2 week phase of the menstrual cycle beginning with the development of the corpus luteum and ending with the beginning of menstrual flow [top]

Luteinizing Hormone (LH)

A hormone secreted by the anterior pituitary gland that stimulates ovulation and corpus luteum development in females and stimulates the development of interstitial tissue in the testis and secretion of testosterone in males. [top]

Lymph

A clear fluid similar in composition to interstitial fluid which pass through lymphatic vessels and tissues into the blood stream via the thoracic duct and right lymphatic duct. [top]

Lymph Nodes

Round masses of lymphoid tissue located around lymphatic vessels which house lymphocytes and macrophages that remove bacteria and debris from lymph. [top]

Lymphatic Capillaries

Thin-walled vessels that function to drain excess tissue fluid from around cells which are to be filtered. [top]

Lymphatic Collecting Vessel

A vessel that accumulates lymph from surrounding lymph capillaries and becomes an afferent lymph vessel as it enters the lymph node. [top]

Lymphatic System

Returns fluid from the body tissues to the cardiovascular system. Plays an important role in body defenses and immunity. Ex. The lymph nodes in the neck (a part of the lymphatic system) often become swollen during infection. [top]

Lymphatic Vessels

Thin-walled vessels containing valves that carry lymph throughout the body. [top]

Lymphoid

Pertaining to lymph or lymphatic tissue. [top]

Lymphoid Organs

Organs of the lymphatic system including: the spleen, tonsils, thymus and bone marrow. [top]

Lymphoid Tissue

Connective tissue containing different types of white blood cells [top]

Lyse

To destroy a cell by lysis; the cell leaks its contents and dies [top]

Lysosome

Engulfs particles in the cytoplasm and breaks them down into usable monomer units [top]

Lysozyme

An enzyme found in saliva that destroys bacteria [top]

MAC Attack

The process of target cells being lysed by the membrane attack complex (MAC) [top]

Macrophages

White blood cells that specialize in consuming pathogens and damaged cells [top]

Macula Densa

A group of modified epithelial cells which lie near the juxtaglomerular cells. These cells relay information on sodium concentration in the filtrate and stimulate the release of renin by the juxtaglomerular cells. [top]

Major Calyces

The large spaces of the renal pelvis [top]

Malleus

The largest, hammer shaped bone of the three ossicles of the middle ear [top]

Mammary Glands

Sebacous glands that are modified to secrete milk in females. They occur in clusters with a network of ducts to allow milk to travel to an external nipple. [top]

Marginate

In white blood cells, refers to the process by which neutrophils cling to the walls of a blood vessel before crossing into the extracellular fluid [top]

Mass Movements

A forceful contraction of large portions of the large intestine; occurs immediately after a meal has been consumed [top]

Mast Cells

A cell found in connective tissue that releases heparin and histamine in response to injury or inflammation [top]

Mastication

To chew food in preparation for swallowing [top]

Mechanical

Controlled or operated by physical activity [top]

Mechanical Digestion

Digestion which takes place in the stomach where the undigested food is churned and hydrochloric acid secreted by parietal cells physically breaks up the food into smaller pieces. [top]

Mechanoreceptor

A sensory receptor on an organ that responds to a mechanical stimulus such as pressure [top]

Media

The middle layer of an organ [top]

Medial

Towards the midline; opposite meaning to lateral. Ex. The sternum is medial to the ribs [top]

Median (midsaggital) Plane

Plane dividing the body into its left and right halves; the plane extends vertically through the body through the dorsal-ventral midline [top]

Medulla

The inner part of a structure or organ [top]

Megakaryocytes

A large cell contained in bone marrow that is the source of platelets [top]

Meiosis

sexual reproduction of cells; a single parent cell produces four unique daughter cells [top]

Membrane

A thin tissue laryer that lines cavities and organs and connects structures [top]

Membrane Attack Complex (MAC)

A complex of 5 different complement proteins which function to pierce the membrane of target cells causing them to lyse. [top]

Membrane Potential

The electrical potential difference inside the cell membrane compared to outside the cell membrane [top]

Memory B Cells

B cells which form after a primary immune response in case of a second invasion. [top]

Meningeal

Relating to the meninges which are the three membranes covering the brain and spinal cord [top]

Meninges

The membrane covering the brain made up of three layers: arachnoid, dura mater and pia mater [top]

Menstrual Phase

The phase of the menstrual cycle where the lining of the uterus is shed [top]

Mesoderm

The middle of the three germ layers of the embryo which will form the bone, muscle, connective tissue and dermis [top]

Metabolism

The combination of all the chemical reactions occurring in the body [top]

Metabolic Reactions

Chemical reactions that contribute to metabolism. Ex. The bicarbonate buffer system in blood is a system of metabolic reactions [top]

Micelle

In digestion, a small droplet of fat surrounded by bile salts that can be absorbed in the small intestine [top]

Microbe

Microorganism that can only be seen through the microscope [top]

Microbiology

A branch of biology dealing with the structure and function of microorganisms [top]

Microcirculation

Blood circulation through small blood vessels such as capillaries, venules and arterioles [top]

Microvilli

Small hairlike structures projecting from the epithelial cells of the small intestine [top]

Micturition (voiding)

The act of expelling urine from the body. [top]

Milk

A white liquid that is secreted from the mammary glands of females to nourish their young [top]

Milk Letdown Reflex

When the hormone oxytocin stimulates the muscles of the breast to release milk to a suckling infant [top]

Mineralocorticoids

A group of steroidal hormones secreted by the adrenal cortex that function to control water and electrolyte balance in the body [top]

Minivalves

Small one-way valves made by the overlapping endothelium cells of lymphatic capillaries [top]

Minor Calyces

The small spaces of the renal pelvis [top]

Mitochondrion

Folded inner membrane surrounded by an outer membrane. Breaks down carbohydrates to produce ATP (energy). [top]

Mitosis

Asexual reproduction of cells; a single parent cell produces two identical daughter cells [top]

Mixed Nerves

A nerve consisting of both sensory and motor fibers. [top]

Mode of Action

The process by which a cell carries out a specific function [top]

Modes of Transmission

Ways that pathogens are transmitted from one host to another. Ex, direct or indirect contact. [top]

Molecules

The combination of two or more atoms; the properties of molecules determine how they interact with one another Ex. Carbohydrates are molecules composed primarily of Carbon and Hydrogen atoms [top]

Monocyte

A phagocytic white blood cell which is formed in the bone marrow and migrates through the blood stream to connective tissue where it become a macrophage. [top]

Monomer

A molecule that can be combined with others to form a polymer [top]

Monosynaptic Reflex

When a reflex arc consists of only two neurons [top]

Morula

A solid mass of blastomeres (embryonic cells) formed by the cleavage of a zygote [top]

Motor

Causing or involving motion [top]

Motor (efferent) division

Portion of the peripheral nervous system consisting of efferent nerves that send motor output information from the integration centers in the brain and spinal cord to effector organs to carry out behavioural and physiological responses. [top]

Motor Information

Information sent from the brain to the peripheral nervous system to initiate movement or reaction [top]

Motor (efferent) Neurons

Neurons that conduct impulses away from the brain and spinal cord (CNS) [top]

Motor Output

Response to a stimulus that is carried out by the body. [top]

Motor Unit

a neuron and all the muscle cells it stimulates [top]

Mouth (oral cavity)

The area of the mouth located behind the teeth and gums including the tongue, hard palate, soft palate and mucous membranes [top]

Mucosa

The membrane made up of epithalial cells and connective tissue that lines the respiratory, digestive, urinary and reproductive tracts. [top]

Mucosa-associated Lymphatic Tissue (MALT)

Lymphatic system tissues found lining the mucosa of the pharynx and small intestine; composed of the tonsils and Peyer's patches [top]

Mucous Membrane

Mucosa; Moist epithelial membrane covering internal passages and cavities that connect to the external environment. Consists of two tissue layers: Epithelium and lamina propria. The epithelium is covered in mucous, a fluid secreted by specialized mucous membrane cells. Ex. The digestive tract is lined with mucous membrane [top]

Mucus

A slimy fluid produced by the mucous membranes which mostens and protects the respiratory, digestive, urinary and reproductive tracts [top]

Multinucleated

Containing more than one nucleus [top]

Multipotent

Having the potential to form only some types of body cells [top]

Muscarinic

A cholinergic receptor on a postganglionic nerve cell of the parasympathetic nervous system. Activates intracellular messaging systems that can slow heart rate, increase secretions of the digestive system and increase muscle activity [top]

Muscle (cardiac)

Muscle tissue with light striations composed of branched cells with a single nucleus joined by special junctions (intercalated discs). Functions in the involontary contractions of the heart. Ex. Found only in the heart [top]

Muscle (skeletal)

Muscle tissue with obvious striations; consists of long, multinucleate cells (muscle fibers). Functions in volontary movements including facial expression. Ex. Attached to the bones and skull of the skeletal system to allow volontary movement [top]

Muscle (smooth)

Muscle tissue with no striations; consists of long, fusiform cells with a single nucleus. Functions in involontary (visceral) movements of dilation or constriction of hollow spaces in the body. Ex. Found in hollow body organs and tubes, such as the bladder, uterus, blood vessels, stomach and intestines [top]

Muscle Cell

Cell of the muscular system. Can be skeletal, smooth or cardiac muscle cells. [top]

Muscle Cell (cardiac)

Short, branching cells with a single nucleus and light striations. Cardiac muscle cells are joined together at intercalated discs. Cushioned by endomysium and arranged in spiral bundles. [top]

Muscle Cell (skeletal)

Long, multinucleated cylindrical and heavily striated cells. Also called muscle fibers. Cushioned by endomysium and arranged in parallel bundles. [top]

Muscle Cell (smooth)

Long, fusiform cells with no striations and a single nucleus. [top]

Muscle Fatigue

condition in which muscles can no longer contract even if stimulated; often results from oxygen demands exceeding supply and an accumulation of lactic acid [top]

Muscle Tissue

Tissue composed of muscle cells specialized for contraction (shortening) to produce movement; Contractile protein filaments move past one another to allow shortening. Ex. Smooth, cardiac and skeletal muscle types [top]

Muscular and Respiratory Pumps

The muscles and respiratory system "squeeze" venous blood back towards the heart when they are in motion. Backflow is prevented by the venous valves. [top]

Muscular System

Creates movement, including locomotion and facial expression. Supports the body to create posture, and produces heat during movement. Smooth, cardiac and skeletal muscles form the muscular system. [top]

Myelin

A white lipid substance found in the membrane of Schwann cells and some neuroglial cells [top]

Myelin Sheath

A fatty layer that encases and insulates nerve fibers and increases the speed of transmission of action potentials. [top]

Myenteric Plexus

A network of nerve fibers and ganglia located between the muscle layers of the alimentary canal; control muscle movements of the alimentary canal [top]

Myocardium

The middle of the three layers of the walls of the heart that is comprised of muscle [top]

Myofibril

bundles of contractile fibers found in skeletal muscle cells [top]

Myofilaments

cellular fibers responsible for the shortening of muscles [top]

Myometrium

The muscular layer of the uterus [top]

Myosin Filaments

thick filaments; form part of the contractile filaments in muscle [top]

Myosin Heads

projections of myosin filaments that make contact with actin and pull on actin filaments to produce muscle contraction [top]

Na+ Channels

Ion channels made up of membrane proteins that conduct sodium ions through cell membranes [top]

Na+/K+ ATP-ase Pump

Sodium-Potassium Adenosine Triphosphatase. An enzyme found in plasma membranes that regulates cellular volume by maintaining levels of sodium and potassium ions inside and outside cell membranes. In neurons it restores the resting potential after an action potential. [top]

Nasal Cavity

The cavity extending from the nostrils to the pharynx between the hard palate and the cranium. [top]

Necessary Life Functions

Functions that must be carried out in order to maintain life. Ex. The maintenance of boundaries (internal and external) is a necessary life function [top]

Negative

an electric charge or voltage that is less than zero [top]

Negative Feedback (system)

A feedback system in which the detection of a stimulus results in the variable dampening the effects of the stimulus and decreasing the body's response. Ex. Body temperature regulation [top]

Negative Membrane Potential

An imbalance in the number of positive ions concentrated near the inner and outer cell membrane [top]

Nephron

A filtering unit of the kidney made up of the Bowman's capsule, proximal convoluted tubule, descending and ascending loop of Henle, distal convoluted tubule and collecting tubules. [top]

Nerves

Bundles of nerve fibers in the peripheral nervous system that carry information to and from the central nervous system. [top]

Nervous

Pertaining to nerves [top]

Nervous System

Electrical and chemical signaling system that controls body movements. Detects and responds to external and internal stimuli. The nerves, brain and spinal cord form the nervous system. [top]

Nervous Tissue

Composed of neurons and their supporting cells; Neurons send electrical impulses throughout the body to coordinate body functions, while the supporting cells nourish and protect the neurons. Ex. Most highly concentrated in the brain and spinal cord, but penetrates all areas of the body [top]

Net Filtration Pressure

The force of fluid entering the Bowman's capsule. [top]

Net Fluid Movement

The amount of fluid lost into the interstitial fluid by blood pressure minus the amount of fluid returned to the blood by osmotic pressure [top]

Neurilemma

The outer membrane of the myelin sheath [top]

Neurofibrils

Threadlike structures contained in a neuon giving it support and shape [top]

Neuroglia (glia or glial cells)

Cells found in the nervous tissue of the brain and spinal cord that act to support, insulate and protect neurons [top]

Neuromuscular Junction

the point of connection between the axon terminal of a neuron and the sarcolemma of a skeletal muscle cell [top]

Neuron

Cells of the nervous system specializing in sending electrical impulses. Neurons connect to one another at synapses. [top]

Neurosecretory

Neurons which synthesize and release hormones into the blood stream. [top]

Neurosecretory Neurons

Small neurons of the hypothalamus which release peptides into the hypothalamic-hypophyseal portal system [top]

Neurotransmitters

Chemical substances released by neurons that bind to neuron receptors to stimulate or inhibit them. Ex, epinepherine, norepinepherine [top]

Neurotransmitter (synaptic) Vesicles

Vesicles within the axon terminal of a neuron which store various neurotransmitters and release them at the synapse [top]

Neutrophil

A phagocytic white blood cell that contains granules which don't stain when dyed. [top]

Nicotinic

A cholinergic receptor on a postganglionic nerve (parasympathetic or sympathetic ) cell that creates excitatory responses in the postganglionic cell. Excites the postganglionic neuron by opening sodium and potassium channels. [top]

Nissl Substance

A material found in nerve cell bodies and dendrites that contains the endoplasmic reticulum and ribosomes [top]

NK (natural killer) Cells

Cytotoxic lymphocytes that release perforin to destroy infected target cells. [top]

Nodes of Ranvier

Small gaps in the myelin sheath of axons [top]

Nonrespiratory Acidosis

Acidosis caused by low bicarbonate levels in the blood with normal carbon dioxide levels. [top]

Nonself Marker

A foreign antigen.[top]

Non-specific Defenses

Body defenses which defend the host from infection by responding to pathogens in a generic way; they do not adapt and they do not provide long-lasting immunity to the host. [top]

Non-specific Internal Defenses

Cells designed to protect the body against types of invaders that have passed the first line of defense and entered the blood and surrounding tissues [top]

Non-steroid Hormones

Hydrophilic molecules that have amino acids as their main structural unit. Because non-steroid hormones are hydrophilic their receptors are on the external surface of the plasma membrane, where they indirectly affect cell activities by activating biochemical pathways in the cell. [top]

Norepinepherine

A neurotransmitter of the sympathetic nervous system and a hormone secreted by the adrenal medulla which causes vasoconstricion and increases in heart rate, blood pressure and blood sugar levels. [top]

Normal Flora

Microbes normally found in a particular area of body. Ex. E. coli is part of the normal flora of the large intestine [top]

Nosocomial Organisms

Infection acquired in hospital. Ex. staphylococcus infection [top]

Nostrils

The two external openings of the nose [top]

Nucleolus

Cell organelle that forms the components of ribosomes [top]

Nucleus

Cell organelle containing the genetic material that directs cell activities [top]

Number

A word or symbol used to count [top]

Occipital Lobe

The posterior lobe of each cerebral hemisphere which contains the brain's visual centers [top]

Occlusion

The normal positioning of teeth where the upper and lower rows meet when the jaws are closed [top]

Odorants

Odourus substances that bind to and activate chemoreceptors in the olfactory system [top]

Olfactory

Relating to the sense of smell [top]

Olfactory Cortex

An area of the cerebellum in the brain where sensory input from the olfactory bulb is receieved via the olfactory tract and smell is perceived [top]

Olfactory Filament

Axon of an olfactory neuron [top]

Olfactory Hairs

Fine, hair-like processes on olfactory cells which contain chemoreceptors [top]

Olfactory Nerve (Cranial Nerve I)

Pair of cranial nerves which conduct nerve impulses from the mucous membranes of the nose to the brain [top]

Olfactory Neurons (Olfactory Receptor Cells)

A receptor neuron which sends sensory information to the olfactory bulb in the brain via the olfactory nerve where smell is detected [top]

Olfactory Receptor Cells (Olfactory Neurons)

A receptor neuron which sends sensory information to the olfactory bulb in the brain via the olfactory nerve where smell is detected [top]

Olfactory Tract

A tract of nerve fibers in the olfactory lobe of the brain that forms a pathway from the olfactory bulb to the olfactory trigone [top]

Opportunistic Organisms

Normal flora that cause infection because they have escaped their particular area or conditions have changed (e.g. change in pH). Ex. E. coli escapes the large intestine and invades the stomach [top]

Optic Chiasma

The site at the base of the brain where the fibers of the left and right optic nerves cross to form a pathway for nerve impulses on the opposite sides of the brain [top]

Optic Nerve

The second pair of cranial nerves that form a pathway for nerve impulses to be conducted from the retina of the eye to the brain [top]

Oral Cavity (mouth)

The area of the mouth located behind the teeth and gums including the tongue, hard palate, soft palate and mucous membranes [top]

Organ

Multiple tissue types working together to perform a specific function in the body of an organism Ex. The heart consists of muscular, epithelial, vascular and other connective tissues [top]

Organ of Corti

A structure within the cochlea of the inner ear consisting of sensory hair cells which act as receptors for auditory stimuli [top]

Organ System

Multiple organs working together to perform a specific function in the body of an organism Ex. The cardiovascular system is responsible for the transportation of nutrients, gases and wastes [top]

Organism

An individual consisting of a number of organ systems working together Ex. A dog is an organism consisting of many organ systems (respiratory, cardiovascular, nervous etc.) [top]

Origin

attachment of a skeletal muscle to the immovable or less movable bone; during contraction, the origin moves towards the insertion [top]

Oropharyngeal Stage

The stage of swallowing involving the oral cavity and pharynx; the tongue angles the bolus towards the back of the mouth, where the pharynx uses peristalsis to push the bolus into the esophagus [top]

Osmosis

Diffusion of water from an area of higher concentration to an area of lower concentration through membrane proteins called aquaporins [top]

Osmotic Pressure

The pressure that develops when a solution is separated by a solvent through a semipermeable membrane where the solvent is only able to pass through [top]

Osseous Tissue

bone; consists of bone cells and a hard matrix composed of collagen fibers with calcium salt deposits. Ex. humerus, femur, ulna [top]

Otoconia (otolith crystals)

Calcium carbonate granuals located in the inner ear which function to stimulate hair cells sending sensory information to the brain [top]

Otolith

Calcium carbonate granuals located in the inner ear [top]

Otolith Crystals (otoconia)

Calcium carbonate granuals located in the inner ear which function to stimulate hair cells sending sensory information to the brain [top]

Otolithic Membrane

A gelatinous membrane located in the inner ear that functions to detect and interpret equilibrium [top]

Oval Window

An oval opening that connects the middle and inner ear through which sound vibrations from the stapes travel [top]

Ovarian

Pertaining to the ovaries [top]

Ovaries

The female reproductive gland which produces ova and secretes hormones that regulate sexual development [top]

Oviduct (Fallopian Tube)

A pair of ducts which transport ova from the ovary to the uterine body [top]

Ovulation

The release of a mature ovum from the ovary [top]

Ovum

Female reproductive cell which produces a zygote when combined with a male's spermatozoon [top]

Oxygen

A colourless and odourless gaseous element which is found in the atmosphere and in water and is essential for respiration [top]

Oxyhemoglobin

The combination of oxygen and hemoglobin located in the red blood cells of arterial blood that functions to carry oxygen from the lungs to the tissues. [top]

Oxytocin

A hormone secreted by the posterior pituitary gland that stimulates uterine contractions and milk secretion [top]

Oxytocin Receptors

Protein receptors located in the central nervous system for the hormone oxytocin. Once these receptors are stimulated milk secretion and uterine contractions begin.

Pacemaker

A body part which maintains the rhythmic activity of the heart [top]

Pain

Unpleasant sensory and emotional experience designed by the body as motivation to withdraw from the situation causing damage to tissues [top]

Pancreas

A large endocrine gland located near the stomach that secretes the hormones insulin and glucagon as well as bile acids into the stomach [top]

Pancreatic Amylase

A hydrolase enzyme secreted by acinar cells in the pancreas which break down disaccharides into monosaccharides. [top]

Pancreatic Duct

A duct connecting the pancreas with the duodenum. [top]

Pancreatic Hydrolase

Enzymes produced in the pancreas. [top]

Pancreatic Lipase

A hydrolase enzyme secreted by acinar cells in the pancreas which break down triglycerides into fatty acids. [top]

Proteolytic Enzymes

Hydrolase enzymes secreted by acinar cells in the pancreas which break down peptides into amino acids. [top]

Papillae

A small projection of a body part similar to a nipple [top]

Papillary Layer

Apical layer of the dermis consisting of a wavy layer of dermal papillae that project into the epidermis. Contains capillaries, pain and touch receptors. Forms the ridges for fingerprints and toe prints. [top]

Paracellular

The transfer of substances between cellular spaces [top]

Parasympathetic

Pertaining to the parasympathetic nervous system. [top]

Parasympathetic Nervous System

Part of the autonomic nervous system that inhibits the physiological effects of the sympathetic nervous system. Promotes energy-conserving and gathering activities by the body. [top]

Parasympathetic Tone

The normal response of the parasympathetic nervous system to stimuli [top]

Parietal

Pertaining to the walls of a cavity [top]

Parietal Cells

Cells of the mucous membranes of the stomach which secrete hydrochloric acid [top]

Passive Reabsorption

The movement of a substance down its osmotic gradient from the filtrate in the nephron into the blood without the use of energy. [top]

Passive Transport

Cell transport in which the movement of substances across the cell membrane is driven by a concentration gradient and requires no energy input from the cell. Passive transport is used to move substances from an area of high concentration to an area of low concentration. Ex. Simple diffusion is a type of passive transport [top]

Pathogen

Disease-causing type of microbe [top]

Pathogenic

Capable of causing disease [top]

Peak

A period of maximum value, use or demand [top]

Pelvic Splanchnic Nerves

Nerves which send impulses to the smooth muscles of the bladder causing contraction of the bladder and involuntary relaxation of the internal urethral sphincter. [top]

Penis

A male organ found in the pubic region that is used in copulation and urine secretion [top]

Pepsin

A digestive enzyme found in gastric juice which causes hydrolysis of peptides and proteins [top]

Pepsinogen

A precursor to pepsin that is secreted by the chief cells in the stomach and is converted to pepsin by hydrochloric acid during digestion [top]

Peptide

A compound containing two or more amino acids [top]

Perforin

A protein produced by immune cells which lyse targeted cells by forming pores in their membranes. [top]

Pericardium

The membranous sac that encases the heart [top]

Perilymph

The fluid in the space between the membranes and bones of the inner ear [top]

Perimetrium

The outer peritoneal layer of the uterus [top]

Perimysium

connective tissue wrapping bundles of muscle cells [top]

Periosteal

Relating to the periosteum which is the membrane of connective tissue situated around or external to bone[top]

Peripheral

Near the surface or towards the outside [top]

Peripheral Nervous System (PNS)

Part of the nervous system that lies outside of the brain and spinal cord consisting of nerves and ganglia [top]

Peripheral Resistance

How difficult it is for the blood to pass through the systemic circulation; affected by the diameter of arteries and the viscosity of the blood [top]

Peristaltic

Pertaining to peristalsis which is the involuntary muscular contraction of the tubular structures of the alimentary canal [top]

Peritoneum

A serous membrane that lines the abdominal cavity [top]

Peritubular Capillaries

Capillaries located in the tubular parts of the nephron to allow substances to move into and out of the blood as urine forms. [top]

Peroxisome

Contains products to oxidize molecules and manufactures bile salts [top]

Peyer's Patches

Lymphoid follicles located in the mucous membrane of the small intestine. [top]

Phagocytosis

Type of endocytosis in which large particles in the extracellular fluid are engulfed by the cell. Ex. Macrophages specialize in phagocytosis of pathogens and damaged cells [top]

Pharmaceuticals

A drug used for medicinal purposes [top]

Pharynx

The tubular structure of the respiratory and digestive tract that is found between the oral cavity and esophagus and connects the mouth and nasal passages with the esophagus [top]

Phosphorylated

has had a phosphate added; Ex. When ADP is converted to ATP it is phosphorylated [top]

Photoreceptor

A sensory receptor on an organ that detects changes in light [top]

Phrenic Nerve

The nerve of the thoracic cavity that acts as the primary motor nerve for the diaphragm, pericardium and pleura. [top]

Physical

Having material existence or pertaining to the body [top]

Physiological Acidosis

Occurs when blood pH between 7.0 and 7.35. It is different from acidosis because it is within the alkaline pH range, but it is "physiologically" acidic because it is more acidic than normal blood pH. [top]

Physiology

The study of the function of the body and body parts of organisms Ex. A physiological feature of the human face is that the nose and mouth are used to breathe in air and expel gaseous wastes [top]

Pia Mater

The highly vascular membrane forming the inner of the three coverings of the brain and spinal cord (meninges) [top]

Pinna

The cartilaginous portion of the external ear [top]

Pinocytosis

Type of endocytosis in which extracellular fluid is taken into the cell. Ex. Many unicellular organisms use pinocytosis to engulf nutrient-rich fluids [top]

Pituitary Gland (hypophysis)

A paired endocrine gland attached to the base of the brain that is separated into anterior and posterior sections and secretes growth hormone, LH, FSH, ACTH, TSH, ADH, PRL and oxytocin. [top]

Placenta

An organ which connects the fetus to the uterus during development and provides metabolic exchange throughout pregnancy without mixing maternal and fetal blood. [top]

Placental Villi

A web of capillaries that project from the placenta into a pool of maternal arterial blood. Nutrient, gas and waste exchange between fetus and mother occur at the placental villi. [top]

Plasma

The fluid portion of blood or lymph that suspends red blood cells, white blood cells and platelets [top]

Plasma Cells

An antibody secreting cell derived from B cells [top]

Plasma Membrane

Phosopholipid bilayer; selectively permeable with a hydrophilic surface and hydrophobic core. Studded with proteins, carbohydrates, glycoproteins, cholesterol and other molecules in a “fluid mosaic”. [top]

Plasma Proteins

Proteins found in blood plasma which include clotting factors such as fibrinogens and transport proteins such as albumin. [top]

Platelets (Thrombocytes)

A cytoplasmic blood constituent which lacks a nucleus and functions in creating blood clots. [top]

Platelet Plug

A blockage formed by the adhering of platelets to the damaged endothelium. [top]

Pleura

The thin serous membrane which encases the lungs and lines the thoracic cavity [top]

Pleural Fluid

The fluid between the visceral and parietal layers of the lungs [top]

Plexus

A network of blood vessels, nerves or lymphatics [top]

Pluripotent

Capable of forming any type of body cell [top]

Podocytes

Cells of the Bowman's capsule that wrap around capillaries of the glomerlulus to allow only small molecules to pass into the Bowman's capsule of the nephron through filtration slits. [top]

Polarized

To separate positive and negative electrical charges [top]

Polycythemia

An abnormal increase in the number of circulating red blood cells in the body [top]

Polysynaptic Reflex

When a reflex arc consists of one or more interneurons connecting with both afferent and efferent neurons [top]

Pons

The thick band of nerve fibers located in the brain stem between the medulla oblongata and midbrain [top]

Portals of Entry

Areas where pathogens may enter the body including: nose and mouth, digestive tract, skin and mucous membranes, genito-urinary tract and blood. [top]

Portal of Exit

The mode by which a pathogen leaves a host in order to be transmitted to a new host; usually the same as the portal of entry [top]

Positive Chemotaxis

To move towards a chemical stimulus [top]

Positive Feedback

A feedback system in which the detection of a stimulus causes the variable to enhance the effects of the stimulus, increasing the body's response. Ex. Child birth [top]

Posterior

Situated behind or to the rear [top]

Posterior Pituitary (Neurophysis)

The posterior portion of a paired endocrine gland attached to the base of the brain that secretes ADH and oxytocin. [top]

Posterior Pituitary Hormones

Hormones secreted by the posterior pituitary gland including oxytocin and ADH [top]

Postganglionic Motor Neuron

A motor neuron that forms a synapse with a preganglionic motor neuron outside of the central nervous system (brain and spinal cord) [top]

Postsynaptic

Occuring at the receiving end of an impulse sent across a synapse [top]

Postsynaptic neuron

A cell of the nervous system that receives a nerve impulse sent from a presynaptic neuron across a synapse [top]

Potassium

A metallic element represented by the symbol K that is important in nerve impulse transmission and osmotic pressure balance in cells [top]

Potassium ion (K+)

A positively charged potassium atom [top]

Precapillary Sphincters

A sphincter at the arterial end of a capillary that controls the flow of blood to tissues [top]

Precursor

A substance or cell from which a new substance or cell is formed. [top]

Preganglionic Motor Neuron

A motor neuron with a cell body contained in the brain or spinal cord and an axon that travels outside of the central nervous system [top]

Pressure

A force exerted over a surface or against resistance [top]

Pressure Points

Areas where a blood vessel runs near bone and pulse can be felt through applying gentle pressure. [top]

Presynaptic

Occuring at the transmitting end of an impulse sent across a synapse [top]

Presynaptic Membrane

A portion of the synaptic cleft where calcium ions fuse during synaptic transmission [top]

Presynaptic Neuron

A cell of the nervous system that transmits a nerve impulse across a synapse to a postsynaptic neuron [top]

Primary Germ Layers

Three cellular groups which make up the layers of the embryo and are formed during embyogenesis. These layers include: ectoderm, mesoderm and endoderm. [top]

Primary Immune Response

An initial immune response that takes place upon first time exposure to an antigen or secondary exposure if no memory cells are present. [top]

Primary Peristaltic Wave

A muscular movement of the esophagus initiated by the vagus nerve to push a food bolus down the esophagus and into the stomach. [top]

Prion

An infectious particle that is similar to a virus but does not carry any genetic material; a misfolded pathogenic protein [top]

Process (projection)

A jutting out or protruding part [top]

Progesterone

Hormone secreted by the corpus luteum in females that functions to prepare the uterus for implantation of the ovum and maintenance of pregnancy [top]

Projection (process)

A jutting out or protruding part [top]

Prolactin (PRL)

A hormone secreted by the anterior pituitary gland that functions to stimulate lactation by the mammary glands at parturition [top]

Proliferative Phase

The phase of the menstrual cycle where estrogen levels rise resulting in the growth of the endometrial lining [top]

Proprioceptors

Receptors located in a joint, muscle or tendon that respond to impulses to allow for locomotion, posture and muscle tone [top]

Prostate Gland

A muscular gland that surrounds the urethra just below the bladder in males, controls the release of urine and secretes seminal fluid to increase motility and fertility of sperm [top]

Protein

Nitrogenous compounds that are essential constituents of living organisms consisting of chains of amino acids [top]

Protein Coat

The protein shell of a virus particle that surrounds its genetic material [top]

Prothrombin

A plasma protein which is converted by activators to thrombin during blood coagulation. [top]

Prothrombin Activator

When PF3 (from platelets), cytokines from damaged tissues and clotting factors in the blood plasma come together to form prothrombin [top]

Protozoa

A single celled microorganism. Ex, Amoeba. [top]

Proximal

Towards the point of origin; opposite meaning to distal. Ex. The wrist is proximal to the fingers [top]

Pseudopod

A temporary projection of the cytoplasm in some cells to aid in locomotion. [top]

Pseudostratified Epithelium

A single layer of columnar epithelial cells resting on basement membrane; cells are not of equal heights creating the illusion of multiple cell layers. Ex. Lining of the respiratory tract [top]

Pulmonary

Pertaining to the lungs [top]

Pulmonary Capillaries

Capillaries located on the surface of alveolar sacs that function to exchange gases with air inside the alveoli [top]

Pulmonary Stretch Receptors

Mechanoreceptors found in the lungs which send impulses to the brain when the lungs inflate to decrease respiratory rate and prevent over inflation. [top]

Pulmonary Ventilation

The process by which air is exchanged between the alveoli in the lungs and the external environment. [top]

Pulse

The palpable throbbing of arteries caused by contractions of the heart [top]

Purkinje Fibers

Muscle fibers which transmit impulses from the AV node to the ventricles of the heart [top]

Pyloric Sphincter

A muscular ring that closes off the pylorus of the stomach after the partially digested food has been passed to the small intestine [top]

Pylorus

Area of the stomach where undigested food exits into the small intestine [top]

Pyrogens

A substance that produces a fever due to metabolic changes in the hypothalamus. [top]

Reabsorption

The act of being absorbed a second time. [top]

Receptive Relaxation

The expanding of the stomach to accommodate undigested food. [top]

Receptor

A part of the nervous system that takes in sensory information. Ex. Heat receptors detect changes in temperature [top]

Receptor-mediated Endocytosis

Type of endocytosis in which specialized surface receptors bind with a specific molecule type in the extracellular space. A vesicle then forms around the complexes of receptor and molecules, taking in only the molecules bound to the receptors. Ex. Cholesterol enters cells by receptor-mediated endocytosis [top]

Receptor Proteins

Proteins integrated into a cell membrane that receive a specific chemical message (neurotransmitter, hormone etc.). The cell that contains the receptor protein then carries out a response. [top]

Recovery Phase

A phase in action potential generation. During this phase, the sodium and potassium ion gradients are restored through the potassium ions being pumped back into the cell and the sodium ions being pumped out of the cell by way of the Na+/K+ ATP-ase pumps. [top]

Recruitment

the number of cells activated by a single stimulus from the nervous system [top]

Rectum

The lower end of the large intestine which ends with the anus where feces is expelled from the body [top]

Red Blood Cells (Erythrocytes)

Cells of blood that have no nucleus but contain hemoglobin which gives blood its red colour and functions to carry oxygen to the tissues. [top]

Red Bone Marrow

Bone marrow which contains the cellular precursors of red blood cells, white blood cells and platelets [top]

Red Pulp

Tissue of the spleen consisting of loose cords containing red blood cells. [top]

Reflexes

An involuntary response to a stimulus [top]

Reflexive Baroreceptors

Specialized neurons which detect changes in blood pressure and send them to the brain stem where they can be mediated by the autonomic nervous system [top]

Refractory Period

A short period directly following muscle or nerve cell response where a second response by the cell cannot be made. [top]

Relaxin

The hormone produced by the corpus luteum which allows relaxation of the pelvic ligaments to facilitate child birth [top]

Relay Molecules

Molecules which relay hormone signals from receptors on the cell's surface to molecules within the cell's cytoplasm or nucleus. [top]

Releasing Hormones

A hormone which controls the release of another hormone. These hormones include Thyrotropin-releasing hormone (TRH), Corticotropin-releasing hormone (CRH), Gonadotropin-releasing hormone (GnRH), Growth hormone-releasing hormone (GHRH) [top]

Renal Artery

Either of two branches of the abdominal aorta which supplies the kidneys with oxygenated blood [top]

Renal Columns

Areas of the renal medulla located between the renal pyramids where blood vessels which travel to and from the renal cortex are found. [top]

Renal Cortex

The outer portion of the kidney containing the glomeruli and proximal and distal convoluted tubules. [top]

Renal Hilum

The area of the kidney that marks the entrance of the renal artery; found on the medial side of the kidney [top]

Renal Medulla

The innermost part of the kidney. [top]

Renal Pelvis

The funnel shaped cavity of the kidney which is continuous with the ureter. Collects urine from the nephrons and funnels it toward the ureter. [top]

Renal Pyramids

Cone shaped regions found within the medulla of the kidney composed mostly of collecting ducts. [top]

Renal System (Urinary System)

Eliminates of nitrogenous wastes; controls water, electrolyte and acid-base balance in bodily fluids. The kidneys, bladder and urethra are all parts of the renal system. [top]

Renal Vein

Carries deoxygenated blood from the kidneys to the inferior vena cava [top]

Renin

An enzyme released by the juxtaglomerular cells of the kidney which hydrolyzes angiotensinogen into angiotensin I. [top]

Repolarization

A change in membrane potential back to its initial resting state [top]

Reproductive System

Creation of offspring and the production of related hormones. Female and male reproductive systems consist of different organs and produce different hormones. The male reproductive system produces sperm and male sex hormones; the female reproductive system produces eggs and female sex hormones. [top]

Reservoir

A living organism in which a parasite or virus lives without damaging its host [top]

Resistance Stage

A long term stress response activated by the sympathetic nervous system by the release of glucocorticoids. During this stage water is retained by the kidneys, blood pressure is increased and the immune system is supressed. [top]

Respiration

The movement and exchange of oxygen and carbon dioxide in the lungs [top]

Respiratory Control Centres

Areas of the brain that function to regulate breathing depending on oxygen demand and carbon dioxide levels in the blood. [top]

Respiratory Gas Transport

The third stage in respiration where oxygen is carried by the hemoglobin in red blood cells to the cells and tissues of the body. [top]

Respiratory Membrane

The epithelial membrane of the alveoli where gas exchange occurs with the blood [top]

Respiratory Muscles

Muscles used in inspiration; external intercostal muscles and diaphragm [top]

Respiratory System

Exchanges gases between the internal and external environments. The lungs use a negative pressure system to breathe air in and positive pressure to breathe out. [top]

Rest and Digest

Referring to the parasympathetic nervous system which is responsible for bodily activities when the body is at rest including tear production, urination, digestion and defecation [top]

Reticular Layer

Basal layer of the dermis containing larger capillaries and cutaneous blood vessels, glands, hair follicles and touch, pain and deep pressure receptors [top]

Reticular Tissue

Tissue consisting of reticular cells and delicate reticular fibers in a fluid matrix Ex. Forms the stroma in lymphoid organs [top]

Retina

A sensory membrane that lines the posterior chamber of the eye which recieves images formed by the lens and converts it into chemical and nervous signals which are transmitted to the brain via the optic nerve [top]

Reuptake

The reabsorption and recycling of previously secreted neurotransmitters by the presynaptic terminal of a neuron while it is sending an impulse to another neuron [top]

Ribosome

Cell organelle that manufactures proteins using an mRNA template [top]

Right Lymphatic Duct

A lymphatic vessel which receives lymph from the right side of the body and empties into the right brachiocephalic vein. [top]

Rising Phase

A phase in action potential generation. During this phase, sodium ions enter the cell through newly opened Na+ ion channels causing rapid depolarization making the negatively charged cell to become positively charged. [top]

Rods (eye)

A rod shaped photosensitive receptor cell in the retina of the eye which functions to detect faint light [top]

Root

1) A nerve fiber bundle that emerges from the spinal cord and joins with another nerve bundle to form a spinal nerve. 2) The part of an organ or cell by which it is attached to the body. [top]

Rotation

movement of a bone around its longitudinal axis without lateral movement. Rotation occurs medially or laterally. Ex. You turn your foot inwards or outwards as it rests flat on the floor. [top]

Rough Endoplasmic Reticulum (rER)

Part of the endomembrane system of cells; manufactures proteins and glycoproteins [top]

Round (circular) Window

A round opening on the medial wall of the inner ear leading to the cochlea. It is covered by a secondary tympanic membrane which compensates for pressure changes. [top]

Saccule

The smaller of the two membranous sacs of the inner ear [top]

Sacral

Relating to the sacral region of the spinal column [top]

Saliva

A clear, aqueous salivary gland secretion which functions to keep the oral cavity moist and initiates digestion of carbohydrates[top]

Salivary Amylase

An enzyme found in saliva which aids in the digestion of starches, breaking polysaccharides into disaccharides[top]

Salivary Centre

An area of the medulla of the brain where input signals are processed and motor signals involving salivation are sent. [top]

Salivary Gland

Exocrine glands which secrete saliva into the oral cavity [top]

Saltatory Conduction

A type of nerve impulse conduction where the impulse jumps from one node of Ranvier to the other rather than travelling through the entire nerve fiber [top]

Sarcolemma

the plasma membrane of a muscle cell [top]

Sarcomere

units of contraction in skeletal muscle; a single sarcomere extends from one Z disc to the next Z disc with the M line at its midpoint [top]

Sarcoplasmic Reticulum

specialized endoplasmic reticulum in muscle [top]

Scab

Hardened mass of red blood cells and clotting factors produced as a temporary barrier during wound healing [top]

Scala Vestibuli

Canal within the bony canal of the cochlea that is continuous with the oval window and receives vibrations from the stapes [top]

Scrotum

An external sac of skin where the testes are contained [top]

Secondary Immune Response

A fast immune response produced by memory cells once a host is introduced to an antigen a second time after a primary immune response has occurred. [top]

Secondary Infection Sites

A second site of infection accessed by a pathogen travelling through the blood stream. [top]

Secretory Phase

The phase of the menstrual cycle where estrogen and progesterone stimulates the growth and secretion of the endometrial lining after ovulation [top]

Secrete

To discharge or release a substance from a cell or gland [top]

Secretin

A hormone secreted by the small intestine which stimulates enzyme secretion by the pancreas and liver [top]

Segmentation

The process of dividing into separate groups or segments [top]

Self-antigen

Markers on blood cells which allow the immune system to identify them so that they are not recognized as foreign and attacked [top]

Self-exciting

Cells that keep rhythmic activity without outside stimuli or influences; most often self-excitation is produced by ion leak channels [top]

Semen

A fluid produced in the male reproductive tract that is comprised of spermatazoa and accessory gland secretions [top]

Semicircular Canals

Curved tubular canals which make up the labyrinth of the ear and are associated with equilibrium [top]

Seminal Fluid

The fluid component of semen [top]

Seminal Vesicle

A pair of glandular sacs located near the bladder in males that secrete a nutrient rich fluid into the ejaculatory duct during ejaculation to promote movement and nourish sperm [top]

Seminiferous Tubules

Coiled tubules located in the testis which function to produce spermatozoa [top]

Sensory Adaptation

When a sensory response diminishes over time after exposure to a constant stimulus. [top]

Sensory (afferent) Division

Portion of the peripheral nervous system consisting of afferent cranial and spinal nerves that send sensory information to integration centers in the brain and spinal cord [top]

Sensory Information

Information about the state of any factor inside or outside the body. Ex. The intensity of light coming through a window is visual sensory information [top]

Sensory (afferent) Neuron

Nerve cell that initiates and carries impulses toward the brain and spinal cord following receptor stimulation [top]

Sensory Receptor

A cell or nerve ending that responds to sensory stimuli [top]

Septicemia

The invasion of the bloodstream with pathogenic microbes [top]

Serous Fluid

Any thin watery fluid of the body [top]

Serous Membrane

Serosa; Moist epithelial membrane forming fluid-filled sacs that line and cushion internal organs. Consists of two layers of serosa (parietal and visceral) surrounding serous fluid. Ex. The pleura surrounding the lungs is composed of serous membrane [top]

Serous Pericardium

The inner layer of the pericardium which functions to prevent friction during heart activity [top]

Sesamoid Bone

Special type of short bone that form inside tendons. Ex. Patella [top]

Set Point

The acceptable range for a specific factor in the body. Ex. The set point for body temperature in a human is 37 degrees Celsius [top]

Sex Hormones

Hormones that are produced by the ovaries, testes or adrenal cortex, such as estrogen and testosterone, that affect growth and function of reproductive organs and the development of secondary sex characteristics [top]

Shaft

An elongated, cylindrical part of the body [top]

Short Bone

Shape classification of bone; Mostly spongy bone in small rough cube shapes. Special short bones called sesamoid bones form inside tendons. Ex. Wrist and ankle bones, patella. [top]

Short Reflexes

Reflexes controlled entirely by the enteric nervous system to regulate motility, secretion and growth of the digestive system. [top]

Short Term

A short period of time [top]

Sigmoid Colon

The "S" shaped part of the colon located between the decending colon and the rectum [top]

Signal Transduction Pathway

A cascade of biochemical reactions which occurs when a molecule or hormone attaches to a receptor on a cell [top]

Simple

Not complex, easy to understand [top]

Simple Diffusion

The passive movement of a solute from an area of higher concentration to an area of lower concentration. Small, lipid-soluble solutes are usually capable of simple diffusion. [top]

Simple Epithelium

A single layer of epithelial cells resting on basement membrane. Ex. Alveolar tissue of the lungs [top]

Simple (basic) Reflexes

Unlearned, involuntary responses to stimuli [top]

Simple Salivary Reflex

A reflex to increase salivation involving the activation of pressure receptors and chemoreceptors in the mouth and the salivary centre in the medulla of the brain. [top]

Sinoatrial (SA) Node

A section of heart tissue which controls the heart beat. [top]

Sinusoids

A small space for blood to flow through tissues of an organ [top]

Skeletal Muscle

Muscle tissue with obvious striations; consists of long, multinucleate cells (muscle fibers). Functions in volontary movements including facial expression. Ex. Attached to the bones and skull of the skeletal system to allow volontary movement [top]

Skeletal Muscle Blood Vessels

Blood vessels found within the skeletal muscles that supply the muscles with oxygen and nutrients. [top]

Skeletal Muscle Cells

Long, multinucleated cylindrical and heavily striated cells. Also called muscle fibers. Cushioned by endomysium and arranged in parallel bundles. [top]

Skeletal System

Protects and supports internal organs and provides the structure needed to support movement. Forms blood cells and stores minerals. The bones form the skeletal system. [top]

Sliding Filament Theory

muscle contraction mechanism [top]

Small Intestine

The part of the small intestine that lies between the stomach and colon that is responsible for absorption of nutrients. It is divided into three parts: the duodenum, jejunum and ilium [top]

Smell

A special sense where odour is perceived by chemical stimulation of the olfactory nerves [top]

Smooth Endoplasmic Reticulum (sER)

Part of the endomembrane system of cells; manufactures lipids, detoxifies substances in the cell [top]

Smooth Muscle

Muscle tissue with no striations; consists of long, fusiform cells with a single nucleus. Functions in involontary (visceral) movements of dilation or constriction of hollow spaces in the body. Ex. Found in hollow body organs and tubes, such as the bladder, uterus, blood vessels, stomach and intestines [top]

Smooth Muscle Cells

Long, fusiform cells with no striations and a single nucleus. [top]

Sodium

A metallic element with the symbol Na that is necessary for maintaining osmotic equilibrium and acid-base balance in the body. Sodium ions also maintain electrical potential in tissues which is important for nerve impulse transmission. [top]

Sodium ion (Na+)

A positively charged sodium atom [top]

Solutes

A substance dissolved in a solution [top]

Solution

A mixture of a dissolving fluid (the solvent) and dissolved substances (the solutes). Ex. Cytosol is a solution with water as its solvent and many dissolved solutes including salts and other ions [top]

Somatic

Relating to or involving skeletal muscles [top]

Somatic Nervous System (SNS)

Division of the peripheral nervous system that innervates skeletal muscle and allows for voluntary motor function [top]

Sound Waves

Longitudinal pressure waves which produce audible sound [top]

Spatial Summation

in muscle contraction, the number of fibers recruited at a given time in a single muscle [top]

Special Senses

Senses that are designed to detect specific types of stimuli. These senses include: vision, hearing, taste and smell [top]

Specific Body Defenses

Response of the immune system to specific pathogens; involves humoral and cellular immunity. [top]

Sperm

Male reproductive cell which produces a zygote when combined with a female's ovum [top]

Sphygmomanometer (Blood Pressure Cuff)

A deviced used to measure blood pressure that is comprised of an inflatable cuff and a manometer to display the pressure value. [top]

Spinal Cord

Thick cord of nervous tissue contained in the spinal canal that carries nerve impulses to and from the brain and carries out reflex actions independent from the brain. [top]

Spinal Nerves

31 nerve pairs which exist in the spinal cord and branch out to innervate specific regions of the neck, torso and limbs [top]

Spinal Reflex

A reflex response that is carried out after a stimulus is received only by the spinal cord [top]

Spirillum

Bacteria with a spiral shape [top]

Splanchnic Nerves

Three nerves formed by the lower thoracic and first lumbar ganglia of the sympathetic nervous system [top]

Spleen

A ductless lymphoid organ lying below the stomach to the left of the abdominal cavity that functions to filter foreign material from the blood, produce lymphocytes and destroy old blood cells. [top]

Spongy Bone

One of the two basic types of bone tissue. Fine pieces of bone form a three-dimensional lattice structure filled with hollow spaces. Ex. Short bones are mostly spongy bone [top]

Squammous Epithelium

Flattened tile-like epithelial cells. Ex. Skin tissue [top]

Stapes

The innermost, stippup-shaped bone of the three ossicles of the middle ear [top]

Starch

A white, tasteless complex carbohydrate that is found in wheat, corn, rice and potatoes [top]

Static System

A system in which there is no flow of materials or energy into or out of the system. Ex. A sealed, insulated box is a static system [top]

Steady State System

A system in which the input and output of energy and materials from the system happen at equal rates. Ex. Each day an organism produces enough energy-rich molecules to fuel its daily activities [top]

Steroid

Natural or organic fat soluble compounds including bile acids and sex hormones [top]

Stimulation

To excite allowing for activation of activity [top]

Stimulus

Anything detected by an organism that will cause a physiological response. Ex. High light levels is a stimulus for constriction of the pupil in the eye [top]

Stomach

A large muscular sac located along the alimentary canal that functions to store food until it has been partially digested [top]

Stops Transcription

Prevents transcription by blocking the promoter region on DNA [top]

Stratified Epithelium

More than one layer of epithelial cells resting on a basement membrane. Ex. Skin tissue [top]

Stratum Basale

Basal layer of the epidermis consisting of rapidly reproducing cells that replenish the upper epidermal layers. Contains melanocytes that produce melanin pigments. [top]

Stratum Corneum

Apical layer of the epidermis consisting of flattened, dead cells filled with keratin. [top]

Stratum Granulosum

Third layer of the epidermis consisting of flattened, keratinized cells [top]

Stratum Lucidum

Second layer of the epidermis consisting of flattened, dead cells filled with keratin. Only present in hairless areas of skin. [top]

Stratum Spinosum

Fourth layer of the epidermis consisting of flattened, keratinized cells. Forms a wavy layer that is shaped by projections from the dermis [top]

Stress Response

A response from the sympathetic nervous system where hormones are secreted to induce exercise and activity. Ex, A prey animal will run away from a predator through activation of the sympathetic nervous system. Also known as a "fight or flight" response. [top]

Stretch Receptors

A sensory receptor located in muscle that is stimulated by stretching of tissue. [top]

Striation

Stripes; alternating banding pattern found in skeletal and cardiac muscle cells caused by the arrangement of contractile fibers. Ex. Skeletal muscles are heavily striated, but cardiac muscles have lighter striations [top]

Striola

The center of the middle ear towards which the macula are oriented [top]

Structure

The arrangement and organization of parts in a substance or body [top]

Structurally

Relating to the structure or physical makeup of a living thing [top]

Subarachnoid Space

The space between the arachnoid membrane and pia mater which is filled with cerebrospinal fluid [top]

Submucosal Plexus

A network of nerve fibers and ganglia located in the intestinal submucosa; control secretions in the alimentary canal [top]

Superficial

Towards the body surface; opposite meaning to deep. Ex. The skin is superficial to the muscles [top]

Superior

Towards the head; up; opposite meaning to inferior. Ex. The head is superior to the neck [top]

Supporting Cells

A group of cell types that act to protect and nourish neurons. Ex, astrocytes, Schwann cells [top]

Surfactant

A lipoprotein substance that coats the alveoli and reduces surface tension to prevent lung collapse. [top]

Survival Needs

Factors that must be present within an acceptable range in order to sustain life. Ex. Food and oxygen are two survival needs of the human body [top]

Swallowing

To pass food through the esophagus into the stomach by way of voluntary muscle action [top]

Swallowing Centre

A group of neurons in the medulla that control the muscles involved in swallowing [top]

Swallowing Reflex

Swallowing due to stimulation of the palate [top]

Sweat Glands

A small, tubular gland found in the skin that secretes sweat [top]

Sympathetic

Pertaining to the sympathetic nervous system. [top]

Sympathetic Chain

Pair of longitudinal cords of the sympathetic nervous system which contain ganglia situated on each side of the spinal column. [top]

Sympathetic Nervous System

Part of the autonomic nervous system that prepares the body to react to situations of stress. Promotes energy-consuming activities by the body. [top]

Sympathetic Postganglionic Neurons

A neuron of the sympathetic nervous system that forms a synapse with a preganglionic neuron outside of the central nervous system (brain and spinal cord) [top]

Sympathetic Tone

The normal response of the sympathetic nervous system to stimuli [top]

Synapse

A point or junction where a nerve impulse is sent from the terminal portion of an axon and received by an adjacent dendrite [top]

Synaptic Cleft

A fluid filled space between neurons across which a nerve impulse is transmitted [top]

Synaptic Terminals

An area of an axon within a presynaptic cell where neurotransmitters are housed [top]

Synaptic Transmission

When neurotransmitters are released by a neuron and cross a synapse to bind and activate the receptors of another neuron [top]

Synaptic Vesicles

Vesicles within the axon terminal of a neuron which store various neurotransmitters and release them at the synapse [top]

Synovial Membrane

Connective (areolar) tissue membrane lining joint capsules, bursae and tendon sheaths. Filled with synovial fluid, secreted by the synovial membrane. Ex. Joint capsules are composed of a synovial membrane and a fibrous capsule (fibrous connective tissue) [top]

System

A group of structures or organs that perform a common function by working together [top]

Systemic

Affecting the entire body [top]

Systolic

The maximum blood pressure measured during the period of the heart beat where the ventricles and atria contract to force blood into the aorta and pulmonary artery. [top]

Target Organ or Tissue

A specific organ or tissue that is affected by a specific hormone [top]

Tastants

Chemicals that bind to and activate taste receptors. Ex, sucrose and sodium chloride [top]

Taste

A special sense where the taste buds of the tongue perceive the sweet, sour, bitter and salty taste of a dissolved substance [top]

Taste Buds

Bodies that lie in the epithelium of the tongue that are made up of sensory neurons which detect the sensation of taste [top]

Taste Pore

Small openings in the tongue that allow for dissolved food in saliva to come into contact with taste receptors [top]

Taste Receptor Cells

A cell of the tongue that contains receptors which facilitate the sensation of taste [top]

Tectorial Membrane

A gelatenous membrane that covers the organ of Corti in the inner ear; transmits sound vibrations from the fluid of the cochlea to the sensory hair cells [top]

Teeth

Bony processes attached to the upper and lower jaws that are used for prehension and mastication of food [top]

Temperature Receptor

A type of sensory receptor found in the skin, cornea and urinary bladder that senses temperature changes [top]

Temporal Lobes

Large cerebral lobes located on each hemisphere of the brain in front of the occipital lobe. They function to perceive hearing and language and control emotion and memory. [top]

Temporal Summation

in muscle contraction, the frequency of fiber recruitment in a single muscle [top]

Tension

pulling force [top]

Terminal Ganglia

Ganglia which occur completely within the organ they innervate. [top]

Testis

A pair of male reproductive glands which produce spermatozoa and androgen hormones and are located in the scrotum [top]

Thoracic

Pertaining to or near the thorax [top]

Thoracic Cavity

One of the ventral cavities; extends from the area of the clavicle to the level of the diaphragm. Ex. The heart and lungs are found in the thoracic cavity [top]

Thoracic Duct

The main vessel of the lymphatic system which passes along the thoracic vertebrae and conveys large amounts of lymph into the bloodstream [top]

Thoracolumbar Division

Also known as the sympathetic division of the peripheral nervous system because the nerves exit the central nervous system in the thoracic and lumbar regions of the spine. [top]

Threshold

The point of beginning or onset [top]

Thrombin

An enzyme formed by prothrombin which is responsible for converting fibrinogen to fibrin during the blood clotting process [top]

Thrombocytes (Platelets)

A cytoplasmic blood constituent which lacks a nucleus and functions in creating blood clots. [top]

Thymosin

A hormone produced by the thymus which stimulates the development of T-lymphocytes. [top]

Thymus

A glandular structure of lymphoid tissue that is the site of T-lymphocyte maturation and is located at the base of the neck [top]

Thyroid Stimulating Hormone

A hormone secreted by the anterior pituitary gland that stimulates and regulates the secretion of the thyroid hormone [top]

Tight Junction

Cell junctions that create impermeable cell layers by binding cells closely together, preventing leakage. Ex. Intestinal wall cells [top]

Tissue

A group of cells working together for a common purpose in the body of an organism Ex. Muscle tissues share the common function of contracting to produce movement [top]

T-lymphocyte

A type of lymphocyte that matures in the thymus and functions to activate and deactivate other immune cells or destroy infected or cancerous body cells. [top]

Tone

Healthy functioning or responsiveness to stimuli [top]

Tongue

The muscular structure located at the floor of the oral cavity which functions in taste perception and assists in mastication and swallowing of food [top]

Tonsils

A pair of lymphod masses located on either side of the throat [top]

Touch

A special sense where pressure on the skin or mucous membrane is perceived [top]

Touch Receptor

Also known as Meissner's corpuscles; a type of sensory receptor found in the skin that is responisble for sensitivity to light touch [top]

Trachea

The tubular structure which leads from the larynx to the bronchi and functions to carry oxygen to the lungs and carbon dioxide away from the lungs [top]

Tract

A specific area or system of organs in the body. Ex. The digestive tract [top]

Transcellular

The transfer of substances passively or actively through cells [top]

Transitional Epithelium

Epithelium with varied apical surface cells; extremely pliable; cells become elongated and flattened when the tissue is stretched. Ex. Urinary bladder [top]

Transmission

The spread of disease from one host to another. [top]

Transverse Colon

The middle part of the colon which sits transversely across the upper abdominal cavity and is located between the ascending and descending colon [top]

Transverse Plane

Plane dividing the body into superior and inferior regions; the plane extends horizontally through the body [top]

Trigone

The triangular area of the inner surface of the bladder. Formed by the two ureteral openings and the internal opening to the urethra. [top]

Trophoblast

The outer layer of a blastocyst which provides the embryo with nutrients and promotes uterine implantation. [top]

Tropic Hormones

Hormones which target other endocrine glands. Ex, the hypothalamus releases hormones which target the anterior pituitary gland. [top]

Tropomyosin

regulatory protein that wraps around actin, blocking myosin binding sites. Can have its shape changed by troponin to reveal myosin binding sites [top]

Troponin

regulatory protein bound to actin filaments that controls the shape of tropomyosin and the binding of actin to myosin; myosin binding sites are revealed on actin when Calcium ions bind to troponin [top]

Trough

A period of minimum value, use or demand [top]

Tunica Externa

The outer layer of a blood or lymphatic vessel [top]

Tunica Intima

The inner layer of a blood or lymphatic vessel [top]

Tunica Media

The middle, muscular layer of a blood or lymphatic vessel [top]

Turbulence

Chaotic motion of air [top]

Twitch

short, low force contraction of a whole muscle [top]

Tympanic Membrane

A thin membrane separating the middle ear from the external auditory canal which vibrates in response to sound and transmits the mechanical vibrations to the auditory ossicles [top]

Umbilical Cord

The cord which connects the fetus to the placenta allowing for transport of nutrients from the mother to the fetus and transport of waste from the fetus to the mother. [top]

Umbilical Region

Abdominopelvic region medial to the lumbar regions, superior to the hypogastric region and inferior to the epigastric region; the area surrounding the navel [top]

Undifferentiated

To have no special function or structure. [top]

Unlearned

Not learned by instruction [top]

Upper GI Tract

The portion of the gastrointestinal tract that is made up of the mouth, pharynx, esophagus and stomach and is responsible for mechanical digestion [top]

Ureter

One of two muscular tubes which transports urine from the kidneys to the bladder [top]

Urethra

A membranous tube that provides a pathway for urine to travel from the bladder to outside the body and also carries semen in males [top]

Urge to Void

The sensation felt when urine presses against the external urethral sphincter [top]

Urinary System (Renal System)

Eliminates of nitrogenous wastes; controls water, electrolyte and acid-base balance in bodily fluids. The kidneys, bladder and urethra are all parts of the urinary system. [top]

Urine

The liquid product of the kidneys made up of waste products from the blood. Urine is stored in the urinary bladder and is expelled from the body via the urethra. [top]

Uterine

Pertaining to the uterus [top]

Uterus

A hollow, muscular organ located in the pelvic area of females where a fertilized ovum will implant itself and develop into a fetus [top]

Utricle

The larger of two membranous sacs which is connected to the semicircular canals of the inner ear [top]

Vagina

A moist canal that extends from the vulva to the cervix and has an external opening between the labia majora in females [top]

Vagus Nerve (Cranial Nerve X)

The tenth pair of cranial nerves that consist of motor fibers which supply the muscles of the the pharynx, larynx, heart and thoracic and abdominal viscera and sensory fibers that conduct nerve impulses from these areas to the brain. The vagus nerve functions to stimulate digestion and regulate heartbeat. [top]

Valsalva Manoeuvre

Contraction of the abdominal muscles and forced expiration against a closed glottis; increases pressure inside the abdomen [top]

Valve

A structure which allows only one way movement through an oriface or vessel [top]

Variable

A factor in the body that can be modified by effectors. Ex. Your muscles shiver to heat your body when it is too cold, modifying the variable of "body temperature" [top]

Variable Regions (light chains)

A pair of polypeptide chains that are a subunit of an immunoglobulin and have a low molecular weight. [top]

Vascular Tissue

Blood; consists of blood cells and a fluid matrix (plasma) and soluble fibrin proteins. Ex. Found in all blood vessels of the circulatory system; penetrates body tissues to transport nutrients, wastes, gases and other substances [top]

Vas Deferens

A duct that runs from the epididymis to the urethra and acts as a passageway for sperm [top]

Vector

An organism that carries a pathogenic microbe from one host to another. [top]

Veins

A blood vessel which carries deoxygenated blood from the cells, tissues and organs back to the heart [top]

Vena Cava

Two large veins that carry blood back to the right atrium of the heart [top]

Ventral Columns

A column made up of the ventral horns of grey matter in the spinal cord where motor neurons are contained [top]

Ventral Horns

The ventral section of grey matter in the spinal cord where motor neurons are contained [top]

Ventricles

A vascular membrane within the pia mater which projects into the cerebral ventricals and secretes cerebrospinal fluid [top]

Vertebral Cavity

A dorsal cavity encompassing the inside of the vertebrae. Ex. The spinal cord is contained within the vertebral cavity [top]

Vesicle

Membrane-bound sacs found within cells that store and transport molecules [top]

Vesicular Transport

The active movement of substances across the cell membrane via a vesicle. Ex. Exocytosis and endocytosis are forms of vesicular transport [top]

Vestibule

A small body cavity or entrance [top]

Vestibulocochlear Nerve (Cranial Nerve VIII)

The eighth pair of cranial nerves which innervate the membranous labyrinth of the inner ear and consist of the vestibular nerve and the cochlear nerve [top]

Vibrio

Bacteria with a comma shape [top]

Villi

Wormlike processes found in the mucous membrane of the small intestine which function to absorb nutrient from partially digested food [top]

Viral

Relating to or caused by a virus [top]

Virulence

Disease-causing ability of a microbe. Ex. pathogens have different types of virulence [top]

Viruses

An infectious submicroscopic agent that is composed of RNA, DNA and a protein coat and grows and multiplies within living cells. [top]

Visceral

Pertaining to the soft organs of the thoracic and abdominal cavities in the body. [top]

Visceral Organs

Organs of the viscera; organs under involuntary control, typically refers to organs of the abdominal cavity. Ex. Stomach, intestines, blood vessels [top]

Vision

A special sense where colour, light, shape and size is perceived through light rays being transformed into elecrical signals in the retina of the eye and transmitted by the optic nerve to the brain [top]

Voiding (micturition)

The act of expelling urine from the body. [top]

Voltage-gated

A type of ion channel that is activated by changes in electrical potential near the ion channel [top]

Vulva

The external parts of the female genitalia including the labia majora, labia minora, clitoris and the vestibule of the vagina [top]

Water

An odourless, tasteless liquid compound of hydrogen and oxygen which is essential for life [top]

White Blood Cells (Leukocytes)

Cells of the blood that are colourless and contain a nucleus and function to help the body fight infection and disease. [top]

White Matter

White coloured nerve tissue containing myelinated fibers found in the brain and spinal cord [top]

White Pulp

Tissue of the spleen consisting of lymphatic nodules. [top]

Wound Healing

The process of repairing tissues after injury [top]

Zona Pellucida

Transperent, noncellular outer layer of the ovum [top]

Zygote

The cell made by the union of an ovum with a spermatozoon [top]