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| Description: (a) Structure of one type of nerve. (b–d) In axons with a myelin sheath, ions flow across the neural membrane at nodes, or small gaps between the cells that make up the sheath. Many gated channels for sodium ions are exposed to extracellular fluid at the nodes. When excitation caused by an action potential reaches a node, the gates open and sodium rushes in, starting a new action potential. Excitation spreads rapidly to the next node, where it triggers a new action potential, and so on down the axon to the output zone.
Picture Stats: Views: 472 Filesize: 401.19kB Height: 861 Width: 1756 Source: https://biology-forums.com/index.php?action=gallery;sa=view;id=47721 Keywords: Peripheral Nervous System |