The
blood vessels carry
blood to and from the
heart and make up the bulk of the circulatory
system. Two features of the
blood that are easily measurable as indicators of overall cardiovascular
function are the
pulse and
blood pressure.
Pulse
Arteries act as
reservoirs to keep
blood pressure up as the
blood travels to the
capillaries.
The
elastic lamina stretches as
high pressure blood is forced through the
arteries during systole, widening the artery. This stretching is felt as the
pulse on the skin's surface if
arteries are close enough to the surface.
Pressure points are areas of the body where the
pulse can be felt.
During
diastole the
elastic lamina recoils (returns to its original size) to push the
blood forward towards the
capillaries.
Blood pressure
Blood pressure is the force of
blood pressing on the walls of
arteries. Both the
systolic and
diastolic pressure of the
blood pushing on the
arteries is measured and both are indicators of overall cardiovascular health.
The traditional method to measure
blood pressure uses a
blood pressure cuff (
sphygmomanometer) wrapped around the upper arm. A stethoscope is then placed onto the arm near the inner elbow to hear the sounds of
blood pumping thorugh the
brachial artery.
When the
blood pressure cuff is fully inflated the flow of blood is completely cut off and no sound is heard. As
pressure is released in the cuff irregular
heart beat sounds can be heard.
Blood pressure is defined by two main components:
Factors affecting blood pressure
The
sympathetic nervous system also controls
blood pressure. The
sympathetic nervous
system activates to increase
blood pressure when:
The
renal system controls
blood pressure through the
renin/
angiotensin II system. It has the ability to increase blood volume, which in turn increases
blood pressure.
Other factors affecting
blood pressure include:
Except where otherwise noted, content on this site is licensed under
1 - Anatomy and Physiology Basics