PSL300H1 Lecture Notes - Neuroglia, Oligodendrocyte, Extracellular Fluid
Document Summary
Psl 300 lecture 3 conduction of action potential. Low current densities do not cause any tissue damage. Alternative = ion diffusion, but too slow and won"t diffuse far before being bound or transported out. The conduction velocity of an ap along an axon depends on the membrane length constant . Measures how quickly a potential difference decays to zero as a function of distance. R = resistance, m = membrane, and i = inside. Measure of passive spread of electrical current, as in any conductor. Increasing membrane resistance is the most efficient means of increasing conduction velocity. Specialized "glial" cells wrap around successive sections of an axon -> myelin sheath. Node of ranvier: a small gap left between adjacent glial cells; the only place exposed to the. In myelinated axons, only the membrane exposed at the nodes is excitable. Ap jumps from one node to the next 5-10 nodes; passive spread of depolarizing occurs between nodes.
