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Wk 5 - Central Nervous System Meninges & Blood Supply Notes...

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Week #5: Central Nervous System – Meninges & Blood SupplyOctober 5, 2015Overview of the Nervous SystemCentral Nervous System (CNS)Consists of the brain and spinal cordPeripheral Nervous System (PNS)Consists of all nervous tissue outside the CNS. Components include:Nerve:bundle of hundreds to thousands of axons plus associated connective tissue and bloodvessels-12 pairs of cranial nerves emerge from the brain-31 pairs of spinal nerves emerge from the spinal cordGanglia:are small masses of nervous tissue, consisting primarily of neuron cell bodies and serves aspecific region of the bodyEnteric plexuses:extensive networks of neurons located in the walls of organs of the GI tractSensory receptors:a structure of the NS that monitors change in the external or internalenvironmentSomatic nervous system (SNS):1 sensory neuron that conveys information to the CNS from somatic receptors in the head, bodywall, and limbs and from receptors for the special senses (vision, hearing, taste, and small)2 motor neurons that conduct impulses from the CNS to skeletal muscles only. Because these motorresponses can be consciously controlled, the action of this part of the PNS is voluntaryAutonomic nervous system (ANS):1 sensory neuron that conveys information to the CNS from autonomic sensory receptors, locatedprimarily in visceral organs (stomach, lungs)2 motor neurons that conduct nerve impulses from the CNS to smooth muscle, cardiac muscle, andglands. Because its motor responses are not normally under conscious control, the action of ANS isinvoluntary-Sympathetic division:‘fight or flight’ – increased alertness and metabolic activity-Parasympathetic division:‘rest and digest’ – energy conservation and replenishing stageEnteric nervous system (ENS):‘Brain of the gut’ is involuntaryConsists of over 100 million neurons in enteric plexuses that extend most of the length of the GItractMany of the neurons of the enteric plexuses function independently of the ANS and CNS, andcommunicate with the CNS via sympathetic and parasympathetic neuronsSensory neurons of ENS monitor chemical changes within the GI tract as well as stretching of thewallsMotor neurons of ENS govern contraction of GI tract smooth muscle to propel food through the GItract, secretions of GI tract organs (stomach acid), and activities of GI tract endocrine cells, whichsecrete hormonesPage1of10
Week #5: Central Nervous System – Meninges & Blood SupplyOctober 5, 2015Functions of the Nervous SystemSensory function:-Sensory receptors detect internal stimuli (increase in BP) or external stimuli (raindroplanding on skin)-This sensory information is carried into the brain and spinal cord through cranial and spinalnervesIntegrative function:-the NS processes sensory information by analyzing it and making decisions for appropriateresponses (integration)Motor function:-

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Term
Fall
Professor
HealthSciencesstaff
Tags
Central Nervous

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