Neuronal fast signalling 1. The characteristics of the neuronal cell What would come to your mind as a defin on? It is a cell of the brain that is not correct, it is more widely spread CNS brain t spinal cord, SNP, enteric system. It is an exc table cell: it is tr ue but this property ss hared with other cells Muscles: striated muscle, heart. And other cells too suh as endocrine cells present an exc t abilit y that is the property to gene rate action potentials which propagates all over the cell. Excitability and conduction are linked properties, and in the cns we find a capabilit y of a very fast conduc tion
1 . The chara cte ristics of the n euronal cell Wha t would come to your mind as a definition? It is a cell of the brain: that is not correct, it is more widely spread: CNS = brain + spinal cord, SN P, ente ric s ystem. It is an exc itable cell: it is tr ue but this property is s hared with other cells. Muscles: striated musc le, heart. And other cells too such as endoc rine cells present an exc itabilit y that is the property to gene rate action potentials which propagates all over the cell. Excitability and conduction are linked prope rties, and in the CNS we find a capabilit y of a very f ast conduc tion. Neuronal fast signalling
It is an integra tive cell. Endocrine cells also are able to integrate sigra ls of dif ferent origins. The spe cificity of the neurone is that it is able to gener ate through symap tic receptors at the level of synap tic contacts a ve ry amplifi ed sigal: 1 molecule of neurotransmtt er htti ng a receptor will all ow the entry of some 1000 ions during its I mill isecond opening This yields a fast signalling. Neu rotransmitt ers which carry this property are: Glutamate, GABA, glycine, and also but less widely distributed acetylcholine, and seroto nin Ad during deve lopment, t is the only cell which moves and ex tends towards Its target cell. This deve lopmental property leads to t he cons truction of very complex networ ks
It is an integra tive cell. Endocrine cells also are able to integrate signa ls of different origins. The spe cificity of the neurone is that it is able to generate through synap tic receptors at the leve l of synap tic contacts a ve ry amplifi ed signa l: 1 molecule of neurotransmitt er hitti ng a receptor will allow the entry of some 1000 ions during its 1 mill isecond opening. This yields a fast s ignalling. Neu rotransmitt ers which carry this property are : Glutamate , GABA, glycine, and also but le ss widely dis tributed acetylcholine , and s erotonin And during deve lopment, it is the only cell which move s and ex tends towards its target cell. This deve lopmental property leads to t he construction of very complex networ ks
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Axon HGURE 16-6 R Ass ntative association (connecting) neu. rons, Arrows indicate direction in which nerve impulse travels (a) Pyramidal cell. (b) Granule cell. (c) Purkinje cell
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