L7 Action Potential Flashcards Preview

Physiology > L7 Action Potential > Flashcards

Flashcards in L7 Action Potential Deck (13):
1

What happens when you inject depolarizing current into a membrane?

the membrane potential will become less negative

you are decreasing the negative charge inside the cell

2

What happens when you inject hyperpolarizing current into a membrane?

the membrane potential becomes more negative

increase negative charges inside the cell

3

What does injecting hyperpolarizing current do?

produces a passive electrical response

4

What does injecting a depolarizing current do?

decreasing the negative charge inside the cell and

produces and action potential

when you reach threshold

5

How is the rising phase of the action potential produced?

by an increase in Na+ conductance (fast Na+ channels)

As the rising phase progresses the conductance of Na increases until we reach the peak.

As we move closer to E Na, the driving force decreases and conductance of Na decreases at the peak

There is a net inward ionic current because a + charged ion (Na) is entering the cell

6

How is the decay phase of an action potential produced?

By a decrease in Na+ conductance and an increase in K+ conductance

This is due to delayed rectifier K+ channels

At the peak of an action potential, conductance of K increases, K+ leaves the cell, and there is a net outward ionic current

The conductance of K decreases as we reach closer to E K and the most hyperpolarized state.

As Vm gets closer to E K, K+ channels close and we move back towards the resting potential.

 

7

Where is there no net ionic current during an action potential?

At the peak

8

Fast Na channels have what two types of gates?

sensitive (rapid) activation

inactivation gates

9

What type of gate does delayed rectifier K+ channels have?

voltage sensitive activation gates

10

What is fast Na+ channel activation responsible for?

Absolute and relative refractory periods

11

What is an absolute refractory period?

Inactivation gates are closed

A new action potential cannot be produced

12

What is the relative refractory period?

A new action potential can be produced, but the threshold is higher.

13

What is the only cell type with a plateau phase?

cardiac cells