1 What two events underlie the fast repolarizing phase of th

1. What two events underlie the fast repolarizing phase of the action potential?

Solution

Hi,

Answer: Factors which underlie the rapid repolarization of action potential:

1. Inactivation gates open

2. Potassium activation gates open

Explanation:

The action potential is characterized by three specialized phases described as depolarization, repolarization, and hyperpolarization. Neurons have special ion channels, called the gated ion channels that make the cell to change its membrane potential in response to stimuli the cell receives. If the stimulus opens a potassium channel, an increase in efflux of potassium will occur, and the membrane potential will become more negative. Such an increase in the electrical gradient across the membrane is called a hyperpolarization. If the channel opened by the stimulus is a sodium channel, an increased influx of sodium will occur, and the membrane potential will become less negative. Such a reduction in the electrical gradient is called a depolarization. During repolarization the membrane returns to its resting potential.

Two factors underlie the rapid repolarizing phase of the action potential as membrane potential is returned to rest. First, the sodium channel inactivation gate, which is slow to respond to changes in voltage, has time to respond to depolarization by closing, returning sodium permeability to its low resting level. Second, potassium channels whose voltage-sensitive gates respond relatively slowly to depolarization, have had time to open.