(8.3)

Question 1

Describe resting potential

Answer 1

This is where the axon has a relative charge of -70mV with more sodium ions being outside the axon and fewer potassium ions occupying inside the axon. The sodium-potassium pump is active and voltage gated channels are shut

Question 2

Describe depolarization

Answer 2

Sodium voltage gated channels open and sodium floods the axon.
This brings the charge within the axon up to 35-40mV and the sodium-potassium channels close

Question 3

Describe repolarisation

Answer 3

In order to bring the charge of the axon back to its resting value the sodium channels shut and the potassium channels open to allow potassium to flood out of the axon. This brings the charge within the axon back towards resting value

Question 4

Describe hyper polarization

Answer 4

The charge within the axon exceeds the normal resting value reaching -90mV
As potassium continues to flood out the axon in order to keep the wave of depolarization unidirectional

Question 5

Describe saltatory conduction

Answer 5

The process in which electrical impulses move down a myelinated sheath with excitation occurring at the nodes of ranvier

Question 6

Describe the all or nothing principle

Answer 6

The minimum amount of depolarization that has to occur within an axon in order to generate a full action potential