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4 Cards in this Set
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neuron: Soma=cellbody. Has nucleus, ER, ribosomes Dendrites extend from soma, receive information, it passes through soma/cell body and up to axon hillock which is connected to axon which has nerve terminal/Synaptic bouton connecting to a muscles or another neuron). synapes connection between neurons Axon: has meyelin sheath plus nodes of ranvier
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Synapses: Have synaptic cleft, synaptic bouton, and postsynaptic membrane (next neuron)
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extra cells supporting neurons are called glial cells. Four types: a) Astrocytes which supply nourishment b) Ependymal cells: produce cerebrospinal fluid to cushion brain c) Oligodendrocytes (CNS) + Schwann cell (PNS)=production of myelin d)Microglia: Ingest pathogens |
signal travelling along axon: 1. Some external stimuli disturns resting neuron voltage from 70mV to "threshold" -55mV, due to more sodium ions travelling form outside neuron into the axon. 2. This opens voltage gated Na+ channels causing an increase in the voltage till "" voltage is reached. Causing Na+ ions channels to deactivate. 3. K+ ion channels open to reduce the voltage to resting voltage. Goes into hyperpolarization, after which Na+ potassium pump takes over to restore the Na+ and K+ balance across the membrane. 4. The " travelling" of electron signal is due to hyper polarization in one area opening Na+ ion channels adjacent to it. |
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IOns channels have threee states: 1. open= allowing movement of sodium ions 2. Inactive= from 35mV to resting potential 3. closed= at resting membrane potential hyperpolarization prevents neurons from firing again or in backward direction. |
Saltatory conduction equals quicker conduction of " electricity". Nodes of ranvier only place for conduction to boost strength signal. Signal can jump a section covered with myelin sheath , lowering the time required for signal travel by reducing number of gated channels required to open. |
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As the signal reaches the nerve terminal, it causes influx of calcium in the terminal (calium ion channels open), this causes vessicles containing neurotransmitter to diffuse through cell membrane. Where they travel through cleft and bind to the receptors on postsynaptic neuron. |
Excitory bind to G protein coupled receptors and inhibitory to ligand gated channels |
