In nerve cell signaling the action potential travels in one direction because: A

Question

In nerve cell signaling the action potential travels in one direction because:

A. the Na+/ K+ pump restores the concentrations of Na+ and K+ to their original levels.

B. the K+ leak channels allow K+ to flow out, restoring the membrane to the resting potential.

C. depolarization of the membrane causes voltage-gated K+ channels to open.

D. voltage-gated Na+ channels adopt a transitory inactive conformation after being opened.

E. voltage-gated Na+ channels spend less time in the open conformation when the membrane returns to the resting potential.

Explanation / Answer

In a nerve cell the signals travel from the direction of axon to the synapse region. during resting state , axon membrane is permeable to potassium ions and semi permeable to sodium ions , causing a gradient in potential , that is more positive charge will be outside , more sodium ions outside and more potasium ions inide , negative charge is more inside.during ressting state ion gated channels are closed and only leaky channels of sodium and potassium are open.

in an action potential, there will be more influx of Sodium ions, and outflux of potassium ions . so more negative charge outside and positive charge inside.the influx of sodium and the outflux of potassium ions continues till charge is stabilised.the channels which are opened are called ion gated channels.

during repolarisation , sodium ion gated channels are closed and the inflow of sodium ions is stopped. potassium ions continue to enter inside to attain negative charge and decrease the positive charge. this restores the resting potential.

during hyperpolarisation, the potassium channels remains open till more and more negative charge is attained inside the cell membrane and more sodium ions are going out in to the extracellular fluid that is outide the cell membrane.

the time period between two action potentials to occur is called the refractory period during which action potential can not happen.

nerve signals cannot travel in the backward direction because the neurotransmitters which are stored in the synaptic vesicles are released during nerve transmission and these fit to the receptors on the dendrites( nerve endings) of the next neuron just like a lock and key model . The receptors sites location and the neuronal structure is one way.

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