Anatomy and Cell Biology 3309 Lecture Notes - Lecture 23: Resting Potential, Axon Hillock, Neuroglia
30 Jan 2017
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Neurons are the information processing cells (electrically excitable) Glial cells there are up to 10 times more glial cells than neurons. Glial cells provide support for neurons, e. g. b(cid:455) suppl(cid:455)i(cid:374)g (cid:862)(cid:271)a(cid:272)k-up(cid:863) glu(cid:272)ose fro(cid:373) glycogen (most glucose comes from blood) By removing ammonia (a by-product of metabolism), A neuron has dendrites (90% of surface area), a soma (cell body), an axon hillock (initial segment), and an axon with collaterals (branches). Incoming axons can ter- minate (synapse) on dendrites, soma or axon terminal. The largest number of synapses are on the dendrites. High electrical resistance between presynaptic and postsynaptic cells (therefore electrical currents ahead of action potential do not cross synapse). The signal which propagates electrically down presynaptic neuron is conveyed across synapse by neurotransmitters (i. e. like that at the neuro muscular junction). Chemical synapses allow integration (summing) of incoming inputs, effects may last from milliseconds to minutes, and may exhibit plasticity.
