Excitation of Nerve and Muscle

Abstract

A difference in potential, the membrane potential, usually exists between the inside of a cell and the extracellular fluid surrounding it. In many types of cells (for example, muscle cells or glandular cells), the function of the cell can be controlled by the magnitude of this potential. It is, in fact, the specialized role of the nervous system to propagate changes in membrane potential within its cells and to transmit them to other cells. These changes in potential can be regarded as units of information that help the body to coordinate the activity of various groups of cells. In particular, the body can feed the information impinging on it from the environment to a center where it is processed, enabling the body to adapt itself in a suitable manner to its surroundings. At the basis of all these functions is the membrane potential and the changes in this potential that spread out through the cells. How the membrane potential is generated and what conditions govern its changes will be discussed in detail in this chapter.