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1F organization of the nervous system.doc

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BIOL 273
Norman Scott

Organization of the Nervous System Central Nervous System - central nervous system: brain and spinal cord - enclosed within the vertebrate - job is to receive info from sensory neurons: sensory info (external (weather)and internal (blood glucose level) - takes info and evaluates it and formulate response - response go to efferent neurons > effector organs: skeletal muscles, visceral organs (organs of digestion, the heart - blood vessels, smooth muscle, endocrine tissues) Peripheral Nervous system anything outside CNS - Afferent: afferent neurons carry signals to CNS - Efferent: carry away - somatic motor neurons: carry signals to effector organ -- skeletal muscles ONLY - autonomic neurons/division: carry signals to all effectors that are not skeletal muscles - autonomic division subdivided into: - sympathetic: if bring signal to heart, heart accelerates and beats faster, stronger, blood flows faster, speed up respiration - fight or flight response - parasympathetic: when at rest, carries opposite signals to sympathetic signals(slow down heart beat) - vegetation, digestion - balance b/t two opposing signals are important - in both branches of autonomic division, two neurons carry signal from the CNS to the effector organ. They are joined by a chemical synapse grouped in cluster --- 'ganglia' - preganglionic neuron: signal carried from CNS to ganglion - postganglionic neuron: signal from ganglion to the effector organ - within all ganglia (sympathetic and parasympathetic) the NT is acetylcholine (ACh). ACh from preganglionic neuron binds to nicotinic cholinergic receptors on the membrane of postganglionic neurons - each ganglia is center of integration (cluster of synapses) and also a signal to diverge (one preganglionic neuron can pass signal onto multi postganglionic neurons) - see illustration in notebook for divergence of the signal in autonomic neurons The Sympathetic Branch - cell bodies of preganglionic neurons are within spinal cord - the axons of most preganglionic cells extend from the thoraric(chest) and lumbar(back) regions to interconnected 'chai
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