Question

The correct order of events associated with an action potential is: When the membrane potential reaches a sufficient level (threshold is achieved), voltage-gated channels open and the charge across the membrane

Answer 1

The correct order of events for an action potential includes depolarization initiated by sodium ions entering the cell, repolarization as potassium ions exit the cell, hyperpolarization during the refractory period, and restoration of the resting potential by the sodium-potassium pump.

Step-by-step explanation:

Understanding the Action Potential Sequence

The sequence of events associated with an action potential involves a specific order of changes in voltage-gated ion channels and ionic movements across a neuron's membrane. Here's the correct order:

1. Depolarization: A stimulus causes the membrane to reach the threshold potential. Upon reaching this level, voltage-gated Na+ channels open, allowing Na+ ions to rush into the cell, which shifts the membrane potential from -70mV towards +30mV.
2. At the peak of the action potential, voltage-gated K+ channels open, enabling K+ to leave the cell and repolarization to occur. Simultaneously, Na+ channels start to inactivate, preventing further Na+ from entering the cell.
3. The membrane potential briefly becomes more negative than the resting potential (hyperpolarization). During this refractory period, the neuron cannot fire another action potential.
4. The K+ channels close, and the sodium-potassium pump works to restore the resting potential of -70mV, re-establishing the concentration gradients of Na+ and K+.

The action potential propagates along the axon as a wave and proceeds only in one direction due to the temporary inactivation of Na+ channels behind the wavefront. A subsequent action potential can only be initiated after the channels have reset to their resting state.

Answer 2

When the membrane potential reaches a sufficient level (threshold is achieved), voltage-gated sodium channels open and the charge across the membrane reverses in a depolarization event. Once the charge across the membrane reãches a peak level, this electrical charge causes voltage-gated potassium channels to open (and the channels previously answered also close). Movement of ions across this now open channel drives the membrane potential to repolarize back toward the resting charge across the membrane. The sodium-potassium pump then resets the ion gradients so that the axon can again be capable of propagating an action potential (Option C).

Step-by-step explanation:

An action potential is a rapid change in membrane potential that occurs in neurons and muscle cells. The correct order of events associated with an action potential is as follows:

1. When the membrane potential reaches a sufficient level (threshold is achieved), voltage-gated sodium channels open and sodium ions rush into the cell, causing depolarization.
2. Once the charge across the membrane reaches a peak level, voltage-gated potassium channels open, and potassium ions begin to leave the cell, driving the membrane potential to repolarize back towards the resting potential.
3. After repolarization, both the sodium and potassium channels close and the sodium-potassium pump resets the ion gradients so that the axon can be capable of propagating another action potential.

Thus, the correct order is sodium, potassium, sodium-potassium (Option C).

Your question is incomplete, but most probably your full question was

The correct order of events associated with an action potential is:

When the membrane potential reaches a sufficient level (threshold is achieved), voltage-gated _____ channels open and the charge across the membrane reverses in a depolarization event. Once the charge across the membrane reãches a peak level, this electrical charge causes voltage-gated _______ channels to open (and the channels previously answered also close). Movement of ions across this now open channel drives the membrane potential to repolarize back toward the resting charge across the membrane. The ______ pump then resets the ion gradients so that the axon can again be capable of propagating an action potential.

A. potassium, sodium, ATP synthase

B. sodium, potassium, ATP synthase

C. sodium, potassium, sodium/potassium

D, sodium, calcium, ATP synthase

E. potassium, sodium, sodium/potassium