Nervous

Nervous - Nervous System What does the nervous system do?...

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Nervous System What does the nervous system do? It allows us to sense internal and external stimuli What components are necessary to accomplish these functions? Neuron: Nerve cell; fundamental unit of the nervous system o Brain: Central processing unit o Nerves: Bundles of neurons running to bodys tissues and  organs Brain and spinal cord: Central nervious system (CNS) Nerves connecting the CNS to the rest of the body: Peripheral nervous  system (PNS) Neurons: Structure/function Electric current generated  o Cell body: Contains nucleus and organelles o Dendrites: receive chemical and electrical signals o Axon: Relays signals o Axon Hillock: Important in generating initial electrical signals o Terminal branches: Send electrical, chemical signals to other  neurons, body cells o Glial cells: Wrap around and protect the axon, Insulte electric  current sent along the axon Myelin sheath: lipid rich  Site of communication between neurons: Synapse Terminal branches end in synaptic terminals o Presynaptic/postsynaptic cells
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Nervous System External and internal stimuli:  Sensory neurons o Long axon; cell body not in the way: Rapid signal transmission Touch smell Interneurons o Many dendrites; short highly branched axons; complex  connections with other cells Interpretation and analysis in brain Not always 100% Necessary Motor neurons o Long axon: Relay signals over distances Effector cell, motor output (Salivation etc) may be up or  down regulatory The plasma membrane separates charges between the internal and  external environments
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Nervous - Nervous System What does the nervous system do?...

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