Question

1. Why are action potentials usually conducted in one direction?

A) The slowing of the sodium potassium pump

B) Brief refractory periods that prevent reopening of voltage gated Na+ channels.

C) Ions can flow along the axon in only one direction

D) A&B

E) B&C

2) Acetylcholine released into the junction between a motor neuron and a skeletal muscle binds to a sodium channel and opens it. This is an example of____.

A) A voltage-gated sodium channel

B) A voltage-gated acetycholine channel

C) A chemical signaling mechanism

D) A second messenger signal

E) A neurotransmitter inhibiting an action potential

Answer 1

1) The correct option is B. Brief refractory periods that prevent reopening of voltage gated Na+ channels.

Action potentials are usually conducted in one direction, because refractory period prevents reopening of voltage-gated Na⁺ channels.

2) The correct option is B. A voltage-gated acetycholine channel.

This is an example of voltage-gated acetycholine channel. The nicotinic acetylcholine receptor, a ligand-gated cation channel accepts both K⁺ and Na⁺. This receptor functions in synapses between motor neurons and skeletal muscle cells.