2.84

2.84: understand that stimulation of receptors in the sense organs sends electrical impulses along nerves into and out of the central nervous system, resulting in rapid responses


Key Points:
1. Messages are carried by nerve impulses and these happen very quickly. These are electrical signals.
2. An impulse travels across the axon rapidly because it can jump from one fat globule to the next (however this only occurs in mammals). This insulates the axon as well.
3. In multiple sclerosis the fatty globules break down and impulses also slow down or even stop. This disease causes people to lose control of their muscles.
4. The axon can be over 1 meter long.
5. Nerve cells have a different structure to other cells, but retain the basic things like cytoplasm, cell membrane and a nucleus. Their shape is stretched out to form the axon.