Figure 11-28. The propagation of an action potential along an axon.

Figure 11-28The propagation of an action potential along an axon

(A) The voltages that would be recorded from a set of intracellular electrodes placed at intervals along the axon. (B) The changes in the Na+ channels and the current flows (orange arrows) that give rise to the traveling disturbance of the membrane potential. The region of the axon with a depolarized membrane is shaded in blue. Note that an action potential can only travel away from the site of depolarization, because Na+ -channel inactivation prevents the depolarization from spreading backward (see also Figure 11-30). On myelinated axons, clusters of Na+ channels can be millimeters apart from each other.

From: Ion Channels and the Electrical Properties of Membranes

Cover of Molecular Biology of the Cell
Molecular Biology of the Cell. 4th edition.
Alberts B, Johnson A, Lewis J, et al.
New York: Garland Science; 2002.
Copyright © 2002, Bruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts, and Peter Walter; Copyright © 1983, 1989, 1994, Bruce Alberts, Dennis Bray, Julian Lewis, Martin Raff, Keith Roberts, and James D. Watson .

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