Question

An action potential is (circle all correct answers)

a reversal of the Na+ and K+ concentrations inside and outside the neuron.

the same size and shape at the beginning and end of the axon.

initiated by inhibitory postsynaptic graded potentials.

transmitted to the distal end of a neuron and causes release of neurotransmitter.

Answer 1

An action potential is the electrical impulse transmitted along a neuron resulting from the flow of Na+ and K+ ions across the neuron's membrane, leading to neurotransmitter release. It is an all-or-nothing event that starts with depolarization and ends with repolarization, followed by restoration of the resting potential.

Step-by-step explanation:

An action potential is a rapid reversal of the electrical charge across the neuron's membrane. It is not a simple reversal of the Na+ and K+ concentrations but rather a temporary and local change in electrical potential that moves down the axon, leading to the eventual release of neurotransmitters. Action potentials are all-or-nothing events, meaning once the threshold is reached, the neuron fires completely. An action potential begins by a depolarization phase where Na+ channels open and sodium ions flow into the cell, making the interior more positive. Following this, repolarization occurs when K+ channels open and potassium ions leave the cell, restoring a more negative membrane potential inside the neuron. The process concludes with the restoration of resting potential through the Na+/K+ pump and other mechanisms.