Medical Sciences 3999A/B/Y Lecture Notes - Lecture 17: Axon Hillock, Substantia Nigra, Silver Stain
16 Feb 2020
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Document Summary
Two cell types: neurons (specialized) and supporting cells (non-conducting) Supporting cells in pns = schwann cells or satellite. Neuron: structural and functional unit of nervous system. End-to-end neurons and their axons make nerve circuits. Junctions between two neurons is the synaptic gap. It is derived from neuroblasts which differentiate to form only one adult nerve cell. Neural stem cells exist in some areas of the brain (may differentiate) Cell body (soma): contains nucleus and cytoplasm (perikaryon) One or many dendrites - relatively short and branching; does not extend very far from the cell. Axon hillock - point where axon commences from cell body. *sciatic nerve axon in pns = >1 m in lower limb. Axon ends in small branches called terminal arborization (telodendria). Each branch terminates on another cell (i. e. glands, muscles, blood vessel walls, neurons, etc. ) in dilatations called end bulbs (boutons). A single neuron may be involved in multiple synapses.
