Propagation of the Action Potential OS 12.4.3 cfu quiz

What initiates the action potential at the beginning of the axon?

• High density of voltage-gated Na+ channels

• Low density of voltage-gated K+ channels

• Presence of neurotransmitters

• Myelination of the axon

Why can't voltage-gated Na+ channels be reopened immediately after depolarization?

• They are permanently closed

• They are inactivated during the absolute refractory period

• They are blocked by neurotransmitters

• They are destroyed after use

How does the propagation of the action potential differ between myelinated and unmyelinated axons?

• It is slower in myelinated axons due to continuous conduction

• It is faster in myelinated axons due to saltatory conduction

• It is the same in both types of axons

• It only occurs in unmyelinated axons

Explain how the distance between nodes of Ranvier affects the speed of action potential propagation in myelinated axons.

• Shorter distances always increase speed

• Optimal distance keeps the membrane depolarized above threshold at the next node

• Longer distances always increase speed

• Distance has no effect on propagation speed

How does the action potential propagate along the axon of a neuron?

• By passive flow of ions only

• By active transport of ions

• By sequential opening of voltage-gated ion channels

• By diffusion of neurotransmitters