MCQ A.3.4. - BasicPhysiology.org

Created on April 01, 2023 By

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MCQ A.3.4.

1 / 3

During the propagation of an action potential along a nerve membrane, current flows are crucial in depolarizing neighboring membranes. Which ions are responsible for this depolarization?

Only sodium ions

Only potassium ions

Both sodium and potassium ions

Only calcium ions

Both calcium and sodium ions

2 / 3

Two action potentials that are propagating towards each other along the same axon will, when they reach other, collide and extinguish each other. Why does this happen?

Because of the presence of an absolute refractory period of both action potentials

Because there are no current circuits generated by the two action potentials

Because the local current circuits will not reach threshold

Because the concentration gradient for potassium and sodium has now disappeared.

3 / 3

This particular nerve cell has a long axon. One action potential is initiated in the soma of that cell and a second action potential is initiated in its pre-synaptic terminals. What will happen?

The two action potentials will propagate along the axon, one towards the pre-synaptic terminals and the other towards the soma until they meet each other hallway, cross over each other and continue their propagation.

The action potential from the soma will propagate throughout the whole axon length because the other action potential, initiated in the pre-synaptic terminals, can not propagate in the opposite direction.

The two action potentials will propagate along the axon, one towards the pre-synaptic terminals and the other towards the soma until they meet each other hallway, collide against each other and are thereby terminated.

The action potential initiated in the pre-synaptic terminal is the only one that will propagate towards the soma and will also propagate along the plasma membrane of the soma.

The action potential from the soma is the only one that will propagate down the axon while the action potential initiated in the pre-synaptic terminals will initiate another action potential in the next nerve cell.

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