Question

What type of feedback occurs when a neuron is stimulated to open a membrane channel, which causes other channels to open?

Negative feedback, because the message is being depressed
Negative feedback, because the message is increasing the effect
Positive feedback, because the message is being amplified
Positive feedback, because the message is weakening the signal

Answer 1

The stimulation of a neuron which causes voltage-gated sodium channels to open in response to sodium influx, leading to further depolarization and opening of more channels, is a positive feedback loop.

Step-by-step explanation:

The type of feedback loop that occurs when a neuron is stimulated, causing voltage-gated sodium channels to open and allowing more sodium to enter the cell, thus causing more channels to open, is known as a positive feedback loop. This loop serves to rapidly amplify the electrical signal during the generation of an action potential. When the neuron reaches its threshold potential, typically around -55 mV, sodium channels in the axon hillock open, leading to a further depolarization of the axon and a sequential opening of additional sodium channels down the axon. This results in the propagation of the action potential until complete depolarization of the neuron occurs. After the action potential, the sodium channels close and enter a refractory period, and potassium channels open to repolarize and hyperpolarize the neuron, resetting the membrane potential back to its resting state.