NRSC 335 Lecture Notes - Lecture 5: Myelin, Axon Hillock, Peripheral Nervous System
5 Feb 2017
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Cell types in brain: nerve cells (neurons, g lial cells (glia) S upport neurons: more numerous than neurons. Neuron doctrine: brain composed of separate neurons. P roposed by s antiago r amon y c ajal (1852-1934) C ontrast this with g olgi"s reticular hypothesis: brain consists of continuously interconnected neurons. Light-sheet (planar) microscopy in clarified brains (c lar ity) C ontinuous with cell body: highly branched, r eceives chemical signals at synapses. C ontains nucleus: r egulates cell functions. Neuron parts: dendrites, axon hillock, g enerates action potential (ap ) S ingle branch from cell body: two branches. S ingle dendrite and axon: many branches, many dendrites and one axon. C onceived to have a large structural role. P rovide structural support: more glia than neurons, myelin production (insulates axons, o ligodendrocytes, wrap around axons forming myelin sheath. C ells contact many axons and/or places on a single axon. S tructural and metabolic support: autonomic nervous s ystem.
