What happens during depolarization?

What happens during depolarization?

• A. Sodium in and Potassium out
• B. Sodium out and Potassium in
• C. Calcium in and Sodium out
• D. Chloride in and Potassium in

Answer: (A)

Depolarization is the phase when the nerve cell’s interior becomes less negative as the stimulus opens voltage-gated sodium channels and sodium rushes into the cell. This inward positive current drives the membrane potential toward zero and beyond, initiating the action potential. The movement described—sodium entering and potassium leaving—captures the main ionic changes associated with this phase, even though potassium efflux is more characteristic of repolarization, which follows depolarization to restore the resting potential. In dental anesthesia, blocking sodium channels prevents this influx, stopping depolarization and nerve conduction.

Depolarization is the phase when the nerve cell’s interior becomes less negative as the stimulus opens voltage-gated sodium channels and sodium rushes into the cell. This inward positive current drives the membrane potential toward zero and beyond, initiating the action potential. The movement described—sodium entering and potassium leaving—captures the main ionic changes associated with this phase, even though potassium efflux is more characteristic of repolarization, which follows depolarization to restore the resting potential. In dental anesthesia, blocking sodium channels prevents this influx, stopping depolarization and nerve conduction.