The process during the action potential when sodium enters the cell causing the interior to become more positive is called?

The process during the action potential when sodium enters the cell causing the interior to become more positive is called?

• A. Hyperpolarization
• B. Repolarization
• C. Depolarization
• D. Resting

Answer: (C)

Depolarization is the phase of the action potential where sodium entering the cell makes the interior more positive. When the membrane reaches threshold, voltage-gated Na+ channels open and Na+ rushes in, lifting the membrane potential from its resting negative value toward positive values. This rising phase is what creates the rapid spike. After depolarization, repolarization occurs as potassium leaves to restore negativity, hyperpolarization briefly makes the interior more negative than resting, and resting is the steady state before the next impulse.

Depolarization is the phase of the action potential where sodium entering the cell makes the interior more positive. When the membrane reaches threshold, voltage-gated Na+ channels open and Na+ rushes in, lifting the membrane potential from its resting negative value toward positive values. This rising phase is what creates the rapid spike. After depolarization, repolarization occurs as potassium leaves to restore negativity, hyperpolarization briefly makes the interior more negative than resting, and resting is the steady state before the next impulse.