2.7 - Nervous Tissue
In multicellular organisms cells of similar structure and function come together to create tissues. Complex organisms have many different cell types that fulfill different structural and physiological needs of the organism. There are four basic tissue types: epithelial, connective, nervous and muscle.
Nervous tissue is most highly concentrated in the brain and spinal cord, but it extends to all parts of the body. Its function is to conduct electircal impulses and chemical signals between body parts to coordinate body physiology, actions and reactions.
Delicate neurons and their supporting cells make up nervous tisuse. Neurons send electrical impulses and communicate amongst themselves and with other body tissues, while supporting cells protect the neurons and provide them with nutrients.
A stimulus causes the neuron to start conducing an electrical impulse along its length. Neurons are extremely long, reaching in excess of 1 meter long in the case of nerves extending to the ends of the legs.