It may make the membrane more positive, a change called
The correct answer and explanation is:
Correct Answer: Depolarization
Explanation (300 words):
When a neuron’s membrane potential becomes more positive than its resting state, this change is called depolarization. Under normal conditions, a neuron’s resting membrane potential is around -70 millivolts (mV), meaning the inside of the cell is more negative relative to the outside. This negative resting potential is primarily maintained by the sodium-potassium pump and the distribution of ions like Na⁺ (sodium), K⁺ (potassium), and Cl⁻ (chloride) across the cell membrane.
Depolarization occurs when positively charged ions, particularly sodium ions (Na⁺), enter the neuron. This influx is usually triggered by a stimulus that causes voltage-gated sodium channels to open. As Na⁺ rushes into the cell, the inside becomes less negative, and if the membrane potential rises to a certain threshold (typically around -55 mV), an action potential (nerve impulse) is initiated.
Depolarization is a critical part of how neurons communicate. Once the membrane reaches this threshold, it rapidly becomes more positive, often peaking around +30 to +40 mV. This sudden change allows the nerve impulse to travel along the neuron’s axon to communicate with other neurons, muscles, or glands.
Following depolarization, the neuron undergoes repolarization, a process where potassium ions (K⁺) exit the cell, restoring the negative resting potential. Sometimes the membrane becomes even more negative than the resting potential, leading to hyperpolarization, before returning to normal.
In summary, depolarization refers to the change in membrane potential that makes it more positive and is essential for initiating and propagating electrical signals in the nervous system. Without depolarization, neurons wouldn’t be able to send messages, and vital body functions such as movement, sensation, and cognition would not occur.