What could cause depolarization of the cell membrane?

What could cause depolarization of the cell membrane?

• A. An acetylcholine-gated ion channel opened on the cell membrane to allow influx of Na+ ions
• B. An acetylcholine-gated ion channel opened on the cell membrane to allow influx of Cl- ions
• C. A glycine-gated ion channel opened on the cell membrane to allow influx of Na+ ions
• D. A glycine-gated ion channel opened on the cell membrane to allow influx of Cl- ions

Answer: (A)

Depolarization of the cell membrane occurs when the membrane potential becomes more positive, typically moving closer to the threshold needed to initiate an action potential. This process often involves the influx of positively charged ions, such as sodium (Na+). When an acetylcholine-gated ion channel opens, it allows the influx of Na+ ions into the cell. This influx is crucial because Na+ ions carry a positive charge, and as they flow into the cell, they cause the inside of the membrane to become less negative (or more positive), leading to depolarization. This event is a key mechanism in the communication between neurons and muscles, as it is necessary for the firing of action potentials. In contrast, channels that allow the influx of negatively charged ions, such as Cl- ions, would lead to hyperpolarization or stabilization of the membrane potential, moving it further away from the threshold for depolarization. Thus, while options involving Cl- ions or glycine-gated ion channels do not lead to depolarization, the opening of acetylcholine-gated channels that permit Na+ entry effectively induces this necessary change in membrane potential.

Depolarization of the cell membrane occurs when the membrane potential becomes more positive, typically moving closer to the threshold needed to initiate an action potential. This process often involves the influx of positively charged ions, such as sodium (Na+).

When an acetylcholine-gated ion channel opens, it allows the influx of Na+ ions into the cell. This influx is crucial because Na+ ions carry a positive charge, and as they flow into the cell, they cause the inside of the membrane to become less negative (or more positive), leading to depolarization. This event is a key mechanism in the communication between neurons and muscles, as it is necessary for the firing of action potentials.

In contrast, channels that allow the influx of negatively charged ions, such as Cl- ions, would lead to hyperpolarization or stabilization of the membrane potential, moving it further away from the threshold for depolarization. Thus, while options involving Cl- ions or glycine-gated ion channels do not lead to depolarization, the opening of acetylcholine-gated channels that permit Na+ entry effectively induces this necessary change in membrane potential.