Neurones

Question 1

What is the all or nothing principle?

Answer 1

States that the size of the impulse is independent on the size of the stimulus
- If the intensity of a stimulus is below the threshold potential, no action potential will be initiated.
- If the intensity of a stimulus is above the threshold value, an action potential is initiated. Any further increase in intensity does not give a greater action potential.

Question 2

What is an axon?

Answer 2

Single long fibre that carries nerve impulses away from the cell body

Question 3

What is a Schwann cell?

Answer 3

They surround the axon by wrapping around it many times and they provide electrical insulation.

Question 4

What is saltatory conduction?

Answer 4

This is where, in myelinated neurones, the action potentials jump between the gaps in the myelin sheath - called the nodes of Ranvier

Question 5

Why is saltatory conduction beneficial?

Answer 5

It increases the speed of electrical conduction