Physiology 3120 Lecture Notes - Lecture 7: Internal Resistance, Fruit Preserves, Tetrodotoxin
28 Dec 2017
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Document Summary
Electric potentials exist across the membrane of all cells of the body. Excitable cells (nerve cells and muscle cells) are capable of generating electrochemical impulses at their membranes: generated from the resting membrane potential. Presynaptic nerve and postsynaptic nerve cells are in contact at the synapse. Cell body: contains the nucleus and dendrites branch from it: dendrites receive the input from the presynaptic nerve. Action potential begins at the axon hillock (electrically sensitive portion of the nerve cell: hillock has high concentration of voltage gated channels. Myelin sheath: wraps axons and allows action potentials to travel quickly. Action potential travels to the axon terminals and synapses on the post synaptic cell: there is more than one axon terminal. To excite the postsynaptic cell, a stimulus must be received from the presynaptic cells: stimulus causes a change in ion permeability in the postsynaptic cell. If the nerve cell was not stimulated, the membrane potential will stay at -70 mv.
