BIOL 200 Lecture Notes - Cumulate Rock, Schwann Cell, Electrochemical Gradient
19 Jan 2013
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Soma: nerve cell body / contains nucleus, cell organelles / synthesise of neurotransmitter. Dendrites: branching extensions from nerve cell soma: stimulated by other neurones \ transmit impulses towards soma. Axon: single extension that extends from the soma to the target cell: myelinated axon is surrounded by schwann cells (myelin sheath, have nodes of ranvier and are rich in myelin (lipid) Voltage-regulated sodium channels open / influx of na+ / down electrochemical gradient. Depolarisation / inside becomes +ve / membrane potential reverses. Potassium channels open (slower than na+ gates) / diffusion of k+ ions out of neurone. Hyperpolarisation due to overshoot in movement of k+out of the cell. //interior of the cell becomes -ve \ membrane is more permeable to k+ ions than to na+ ions. [graph] highest positive membrane potential is the action potential. The role of the neurone membrane in the establishment. Membrane is polarised: inside of axon is more -ve than outside.
