1.6

Question 1

Define what AP is

Answer 1

electrical messaging phenomenon of excitable cells

rapid depol and repol

Question 2

What are the charactaristics of all AP?

Answer 2

1. size and shape
2. threshold
3. propagation without decrement צמצום
4. All-Or-None phenomenon

Question 3

Steps in neurons AP generation

Depolarization

Answer 3

1. Em= -70 mV
2. ligand binds Channel (lets say ACh)
3. lignad gated Na+ ch opens and Na+ influx
4. depol until threshold (-50 mV)
5. voltage gated Na ch open, more Na influx

Question 4

Steps in neurons AP generation

Repolarization

Answer 4

1. slow inactivation gates on VGNaCh

2. VGKC open and K+ efflux

Question 5

what is the absolute refractory period?

Answer 5

due to closure of the inactivation gates of the VGNaCh

no AP can be generated!

Question 6

what is the relative refractory period?

Answer 6

due to Hyperpolarization via high K+ permeability

*stronger than normal stimulus is needed in order to create new AP

Question 7

3 main difference in the cardiac AP

Answer 7

1. longer duration
2. plateau phase
3. longer refractory period

Question 8

How can we increase conduction velocity?

Answer 8

1. Nerve diameter (higher=faster. remember resistance is inversley prop to cross-sectional area
2. myelination