Question

multiple choice question
which of the following defines a nerve signal?
o the process of pumping na+ out of the cell and k+ into the cell
the amount of stimulus required to open voltage - gated channels at the axon hillock
a chain reaction of action potentials in the membrane
motor proteins carrying substances up and down the axon

Explanation:

• The process of pumping \(Na^+\) out of the cell and \(K^+\) into the cell is related to the sodium - potassium pump which maintains the resting membrane potential, not the nerve signal itself.
• The amount of stimulus required to open voltage - gated channels at the axon hillock is the threshold, not the nerve signal.
• Motor proteins carrying substances up and down the axon is axonal transport, not a nerve signal.
• A nerve signal is a chain reaction of action potentials in the membrane. When an action potential occurs at one point on the membrane, it depolarizes the adjacent region, causing an action potential there, and so on.

Answer:

a chain reaction of action potentials in the membrane