What process describes how a signal travels from one end of a neuron to the other end?
A. Membrane excitability
B. Neurotransmitter release
The neurotransmitter release occurs within the synapse. Does that give you a clue?
I hope this helps. Thanks for asking.
The process that describes how a signal travels from one end of a neuron to the other end is called "Membrane excitability."
Membrane excitability refers to the ability of the neuron's cell membrane to change its electrical potential in response to a stimulus. This process involves the movement of ions, such as sodium (Na+) and potassium (K+), across the cell membrane, which generates electrical signals called action potentials.
Here's a step-by-step explanation of how the process of membrane excitability allows a signal to travel from one end of a neuron to the other end:
1. Resting Potential: When a neuron is not stimulated, it is at its resting potential. At this stage, the inside of the neuron is negatively charged relative to the outside due to an uneven distribution of ions across the membrane. This is maintained by the sodium-potassium pump, which pumps out three sodium ions (Na+) for every two potassium ions (K+) it pumps in.
2. Depolarization: When a stimulus reaches the neuron, it can cause the opening of ion channels in the cell membrane. Specifically, voltage-gated sodium channels open, allowing sodium ions to rush into the neuron, making the inside more positively charged. This influx of positively charged sodium ions depolarizes the membrane, meaning it becomes less negative.
3. Action Potential: If the depolarization reaches a certain threshold, it triggers an action potential. This is an all-or-nothing event where the membrane potential rapidly reverses. Voltage-gated sodium channels open fully, while voltage-gated potassium channels begin to open more slowly. Sodium ions rush into the neuron, reversing the polarity, and the inside becomes positively charged relative to the outside.
4. Repolarization: After the peak of the action potential, the voltage-gated sodium channels close, preventing more sodium ions from entering. At the same time, the voltage-gated potassium channels open fully, allowing potassium ions to flow out of the neuron. This movement of potassium ions out of the cell increases the negativity inside the neuron, repolarizing the membrane.
5. Hyperpolarization: In some cases, the potassium channels may stay open for slightly longer than necessary, resulting in an overshoot of the resting membrane potential. This temporary, excessive negativity is called hyperpolarization.
6. Resting State: The sodium-potassium pumps actively restore the ion concentrations to their original state, re-establishing the resting potential and preparing the neuron for another action potential if necessary.
So, the correct answer to the question "What process describes how a signal travels from one end of a neuron to the other end?" is A. Membrane excitability.