Question

An action potential does not re-stimulate the adjacent membrane that was previously depolarized because

A. stimulation is inhibited by the myelin sheath. B. it is impossible for an action potential to be propagated along an axon toward the nerve cell body. C. the resting membrane potential of the axon is too positive. D. the resting membrane potential of the axon is too negative. E. that area of the membrane is in the absolutely refractory period.

Answer 1

An action potential does not re-stimulate the previously depolarized adjacent membrane because it is in the absolute refractory period, preventing the reopened of inactivated sodium channels and thus ensuring the unidirectional propagation of the action potential.

Step-by-step explanation:

An action potential does not re-stimulate the adjacent membrane that was previously depolarized because that area of the membrane is in the absolute refractory period. During the absolute refractory period, the voltage-gated sodium (Na+) channels, which open during depolarization to allow Na+ ions into the cell thus initiating the action potential, are inactivated and cannot reopen until they return to their resting state. This ensures that the action potential only travels in one direction along the axon, towards the axon terminals.

The refractory period is critical in the sequential firing of action potentials and maintaining the unidirectional flow of nerve impulses. The sodium-potassium pump will eventually restore resting potential after this period, but until then, no new action potentials can be initiated in the refractory zone. Therefore, the correct answer to the student's question is E. that area of the membrane is in the absolute refractory period.

Answer 2

E. that area of the membrane is in the absolutely refractory period.

Step-by-step explanation:

Refractory period is a period during which neuron cell cannot be stimulated (depolarized). This is why the action potential can only travel in one direction from the neuron body towards axon.

Refractory period occurs because of the inactivation of voltage-gated sodium channels (while action potential is at its peak) which cannot be open for a certain period of time. and membrane cannot be depolarized.