Question

ction potentials typically move in one direction along the neuron away from the cell body. This is due to which of the following?A. the temporary hyperpolarization of the axon membrane following the action potential spikeB. the temporary inactivation of sodium and potassium channels following the action potential spikeC. the movement of sodium ions out of the cell D. the myelination of the axon membrane

Answer 1

Answer:

The correct answer is option A. "the temporary hyperpolarization of the axon membrane following the action potential spike".

Explanation:

Action potentials, also known as "spikes" or "impulses", are electric impulses that neurons use to send information from the cell's body down to the axon. The impulses are created when ions travel across the neuron's membrane creating a depolarization current. This depolarization current is responsible for an temporary hyperpolarization of the axon membrane following the action potential spike. When neurons are hyperpolarized they are not able to produce another action potential. In consequence, actions potentials move in one direction along the neuron away from the cell body, as well as, adjacent locations go trough similar depolarization processes.

Answer 2

ANSWER:

NONE OF THE ABOVE OPTIONS GIVEN ARE CORRECT.

Correct answer is that Action potentials typically move in one direction along the neuron away from the cell body because the absolute refractory period prevents a depolarization from occurring in the direction from which the impulse came.

EXPLANATION:

Axons are a key component of a neuron, they conduct electrical signals in the form of an action potential from the cell body of the neuron to its axon terminal where it synapses with another neuron. An axon is insulated by a myelin sheath throughout its length to increase the velocity of these electrical signals allowing signals to propagate quickly.

Axons which are covered by a myelin sheath, a multilayer of proteins and lipids, are said to be myelinated. If an axon is not surrounded by a myelin sheath, it is unmyelinated. Myelination is the formation of a myelin sheath. Myelin sheaths insulate axons to increase the speed of electrical signal conduction. This allows myelinated axons to conduct electrical signals at high speeds.

Once an action potential has occurred at a patch of membrane, the membrane patch needs time to recover before it can fire again. At the molecular level, this absolute refractory period corresponds to the time required for the voltage-activated sodium channels to recover from inactivation, i.e., to return to their closed state.

THE ABSOLUTE REFRACTORY PERIOD ensures that the action potential MOVES IN ONLY ONE DIRECTION along an axon. The currents flowing in due to an action potential spread out in both directions along the axon. However, only the unfired part of the axon can respond with an action potential; the part that has just fired is unresponsive until the action potential is safely out of range and cannot restimulate that part.