Pacemaker AP quiz

Question 1

List all the phases involved in the pacemaker action potential

Answer 1

Phase 0, phase 3, and phase 4

Question 2

What happens in Phase 0?

Answer 2

opening of calcium channels,

inactivation of fast sodium channels

Question 3

When are fast voltage-gated sodium channels permanently inactivated?

Answer 3

Phase 0

Question 4

How does the AV node prolong transmission of the action potential from the Atria to the ventricles?

Answer 4

via permanent inactivation of fast voltage-gated sodium channels

Question 5

What happens in phase 3?

Answer 5

Repolarization, inactivation of calcium channels

and

activation of potassium channels leads to potassium efflux

Question 6

What are the funny current channels responsible for?

Answer 6

A slow mixed sodium and potassium inward current

Question 7

In what phase are the funny current channels activated?

Answer 7

Phase 4

Question 8

The slope of phase 4 in the SA node determines what?

Answer 8

Heart rate

Question 9

How are funny channels activated?

Answer 9

slow spontaneous diastolic depolarization of the funny channels

Question 10

What accounts for the aromaticity of SA and AV nodes?

Answer 10

The funny current

Question 11

How does sympathetic stimulation affect Channel activation?

Answer 11

Sympathetic stimulation increases the chance that funny channels are open that’s increasing heart rate