A common feature of action potentials is that they
A) cause the membrane to hyperpolarize and then depolarize.
B) can undergo temporal and spatial summation.
C) are triggered by a depolarization that reaches the threshold.
D) move at the same speed along all axons.
E) require the diffusion of Na⁺ and K⁺ through ligand-gated channels to propagate.

Question

Quizplus · Accepted Answer

Action potentials are triggered by a depolarization that reaches the threshold. This depolarization causes the opening of voltage-gated ion channels, which leads to the generation and propagation of the action potential.

Answer: B
 Action potentials can undergo temporal and spatial summation. Temporal summation occurs when multiple small stimuli are delivered to the neuron in a short period of time, while spatial summation occurs when multiple stimuli are delivered simultaneously to different regions of the neuron.

Note: While there are some variations in the speed of propagation of action potentials along different axons, it is not accurate to say that they move at the same speed along all axons (D). Choice (E) is also incorrect, as the propagation of the action potential involves the opening of voltage-gated ion channels, not ligand-gated channels. Choice (A) is also not accurate, as action potentials cause depolarization, not hyperpolarization, followed by repolarization.

A Common Feature of Action Potentials Is That They