Why does an action potential only reach a particular value?
A) Potassium channels close
B) Sodium channels close
C) Excitatory postsynaptic potentials cease
D) Sodium-potassium pump activity resumes

Question

Quizplus · Accepted Answer

An action potential is generated when sodium channels open, allowing a large influx of positively charged sodium ions into the cell. However, these channels are only open for a brief period of time before they close. Once the membrane potential reaches a certain threshold and the sodium channels have closed, the action potential cannot continue to increase in magnitude. The subsequent repolarization phase is caused by potassium channels opening and allowing positively charged potassium ions to exit the cell, which helps bring the membrane potential back to its resting value. However, this process does not cause the action potential to reach a particular value, as the peak amplitude is determined by the initial influx of sodium ions. Therefore, the best choice is B - sodium channels close.

Why Does an Action Potential Only Reach a Particular Value