Objective 9

Question 0

Generation / propagation of the Action Potential:

Describe what happens after the initial patch of sarcolemma changes permeability of the adjacent patch?

Answer 0

Volatage-regulated Na+ channels now open in the adjacent patch causing it to depolarize
- thus the action potential travels rapidly along the sarcolemma

Question 1

Describe how generation / propagation of the Action Potential begins

Answer 1

Polarity reversal of the initial patch of sarcolemma changes permeability of the adjacent patch

Question 2

Generation / Propagation of the AP:

What happens one the action potential travels rapidly along the sarcolemma?

Answer 2

Once initiated, the action potential is unstoppable, and will result in contraction of a muscle.

Question 3

Generation / Propagation of AP:

How does regeneration occur?

Answer 3

The same way as in the motor axon

• Na+ channels close and K+ channels open @ +30mV
• K+ diffuses out of the cell, restoring the electrical polarity of the sarcolemma

Question 4

Generation / Propagation of the AP:

In what direction does repolarization occur?

Answer 4

In the same direction as depolarization

Question 5

Generation / Propagation of the AP:

What must occur before the muscle can be stimulated again?

Answer 5

repolarization must occur before the muscle can be stimulated again (refractory period).

Question 6

Generation / Propagation of the AP:

How is the ionic concentration of the resting state restored?

Answer 6

Ionic concentration of the resting state is restored by the Na+-K+ pump