Action potential

Question 1

Which ion is most important in repolarization?

Answer 1

K+

Question 2

Tetrodotoxin, caine drugs?
Tetraethylammonium?
Ciguatoxin?

Answer 2

• Block Na+ channels > No AP
• Blocks K+ channels > long repolarization
• Opens Na+ channels > AP

Question 3

Absolute refractory?
Relative refractory?

Answer 3

• All Na+ channels open
• Strong stimulus > AP in hyperpolarization

Question 4

Hyperkalemia?
Hypercalcemia?

Answer 4

• Keeps cells depolarized
• Ca2+ block Na+ channels

Question 5

Bigger Tau?
Smaller Tau?
Advantage of larger tau?

Answer 5

• Slower change in Vm
• Faster change in Vm
• Can sum Vm to reach threshold

Question 6

Small lambda?
Large lambda?

Answer 6

• Current travels shorter distance before losing 63%
• Farther distance

Question 7

Velocity increases if we:
_ diameter
_ capacitance

Answer 7

• Increase
• Decrease(myelination)

Question 8

Demyelinating diseases(2)
What does it do?

Answer 8

• MS(CNS), Guillain Barre syndrome(PNS)
• Blocks saltatory conduction