**Question:** In action potential of nerve, the overshoot is:

A. Depolarization
B. Hyperpolarization
C. Equilibrium potential
D. Resting membrane potential

**Core Concept:**

An action potential is a rapid change in the membrane potential of a nerve cell, resulting in the depolarization or hyperpolarization of the cell membrane. This transient change in membrane potential is essential for the transmission of nerve impulses and the generation of electrical signals in the nervous system. In the context of this question, the overshoot refers to the point after the peak of the action potential, when the membrane potential temporarily rises above the resting membrane potential before returning to its resting level.

**Why the Correct Answer is Right:**

The correct answer, B. Hyperpolarization, refers to the overshoot occurring after the peak of the action potential. When the action potential reaches its peak, the membrane potential temporarily moves away from the resting membrane potential, causing hyperpolarization. Resting membrane potential is the normal state of the neuron membrane, with a potential of -70 mV.

**Why Each Wrong Option is Incorrect:**

A. Depolarization: This refers to the process of moving towards the positive end of the voltage scale, which is the opposite of hyperpolarization. As a result, it is incorrect as it does not represent the overshoot in action potential.
C. Equilibrium potential: This term is related to the potential at which the net charge across the membrane equals zero. It is not the same as the action potential overshoot and therefore incorrect.
D. Resting membrane potential: This refers to the normal state of the neuron membrane, with a potential of -70 mV. Although important for understanding the context, it is not the correct term for the overshoot in action potential.

**Clinical Pearl:**

Understanding the action potential and its various stages is crucial in understanding how neurons transmit signals. The action potential is a fundamental concept in physiology and anatomy, and the correct answer highlights the concept of hyperpolarization following the peak of the action potential. This is essential for medical students and practitioners alike, as it contributes to the overall understanding of nerve cell function and communication within the nervous system.