Membrane Potential

The membrane potential of a cell refers to the difference in electric charge between the interior and exterior of the cell, which is maintained by the selective permeability of the cell membrane to certain ions. This difference in charge is essential for many physiological processes, including the transmission of nerve impulses and muscle contractions.

Key Concepts

1. Ions: Atoms or molecules that carry a positive or negative charge due to the loss or gain of electrons. In the context of membrane potential, the ions of interest are typically sodium (Na+), potassium (K+), and chloride (Cl-).
2. Resting Membrane Potential: The membrane potential of a cell at rest, typically around -70 millivolts (mV) in nerve cells. This resting potential is maintained by the unequal distribution of ions across the cell membrane.
3. Ion Channels: Proteins embedded in the cell membrane that allow specific ions to pass through, thus influencing the membrane potential.
4. Electrochemical Gradient: The combined influence of concentration gradients and electrical gradients on ion movement across the cell membrane.
5. Action Potential: A rapid change in membrane potential that allows nerve cells to transmit electrical signals. It involves a temporary reversal of the membrane potential, followed by a return to the resting state.

Study Guide

To understand membrane potential, it's important to grasp the following concepts:

1. Define membrane potential and explain its significance in cellular function.
2. Describe the roles of key ions (sodium, potassium, chloride) in establishing and maintaining membrane potential.
3. Explain the concept of resting membrane potential and how it is maintained in cells.
4. Discuss the function of ion channels in regulating the movement of ions across the cell membrane.
5. Explore the concept of electrochemical gradient and its influence on ion movement.
6. Describe the process of action potential and its role in nerve cell signaling.

By mastering these concepts, you will develop a solid understanding of membrane potential and its importance in cellular physiology.