The Action Potential

Question 0

Give the 4 phases of the action potential?

Answer 0

Resting, depolarisation, polarisation and afterhyperpolarisation

Question 1

What does a stimulus result in?

Answer 1

Small patch of of membrane becoming depolarised

Question 2

What direction are action potentials propagated in?

Answer 2

Axon hillock to the axon terminal

Question 3

A larger stimulus will produce?

Answer 3

A greater number of action potentials

Question 4

How does the permeability for NA and K change during and action potential?

Answer 4

At rest NA and K closed, during depolarisation NA open, during polarisation K open while NA close, undershoot K open and NA closed

Question 5

What does the all-or-nothing hypothesis state?

Answer 5

Unless the depolarisation reaches the threshold of -50 mv an action potential will not fire

Question 6

What is the absolute refractory period?

Answer 6

A period where no further action potential can fire as the cell has to recover to resting state. It ensures the unidirectionality of the action potential.

A huge stimulus could cause an action potential in this period.

Question 7

What does the magnitude of the action potential do at different magnitudes of stimulus?

Answer 7

It varies, a large stimulus equals a greater magnitude

Question 8

What happens do the amplitude of an action potential as it travels away from the site of production?

Answer 8

Decreases

Question 9

What mechanisms are used to move ions across plasma membranes?

Answer 9

Ion pumps and ion channels