PSYC 1001 Lecture Notes - Lecture 3: Axon Hillock, University Of Manchester, Myelin
Document Summary
Astrocytes form barrier between blood in capillaries and fluid surrounding neurons. In body, capillaries have small gaps through which substances can pass. Helps prevent charged molecules, water soluble molecules, large. Function: removal of deteriorating myelin and dead neurons (phagocytosis) Schwann cell: single cell wraps around axon to produce a myelin sheath (pns) Oligodendrocyte: one cell wraps processes around the axons to make sheaths on several neurons (cns) Nodes of ranvier: separations between segments of myelin neurotransmitters (nt) released from end of axon: terminal buttons: interface with the receiving neuron/cell. Resting potential neurons at rest inside is electrically negative relative to the outside (-60 mv) due to distribution of charged particles (ions) across the membrane. Outside > na+, cl- (outside sea is salty) Action potential: electrical impulse necessary to trigger an action potential. Absolute refractory period: time during which another action potential is impossible; limits maximum firing rate. Action potential depolarization if threshold reached ay hillock (-55mv) voltage-gated na+ gates open.
