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Lecture 5 - Nervous system - 2 per page JZ.pdf - 20171004...

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2017‐10‐041Nervous systemResources:12.1‐12.313.1‐13.2Labs 16‐17OutlineNervous tissue (Ch. 12)Overview of the nervoussystemProperties of neuronsNeuroglia, myelinationSpinal cord and spinal nerves (Ch. 13)OrganizationCross section organizationAscending, descending tractsSpinal nervesGeneral anatomy of nervesand gangliaPlexuses – networks ofintersecting nerves
2017‐10‐042Internal communicationEndocrine and nervous system maintain internal coordination1.Endocrine systemuses hormones secreted into blood“long‐distance” communicationslow2.Nervous systemuses electrical and chemical meanssends message from cell to cellvery quick (e.g. reflexes, perception)Nervous system is tightlyintegrated with all otherbody systems
2017‐10‐043Central nervous system (CNS)Brain and spinal cordEnclosed by cranium and vertebral columnPeripheral nervous system (PNS)Everything else distributed through body: cranial and spinalnerves, gangliaComposed of nerves and gangliaNerves ‐ bundle of nerve fibres (axons) wrapped in fibrousconnective tissueGanglion ‐ knot‐like swelling in a nerve where neuron cellbodies are concentratedTwo divisions (sensory and motor), each with somatic andvisceral subdivisionsNervous system componentsNervous system organization: input/ output1. Sense organs receive informationand transmits coded messages tothe CNSInformation: patternedchanges in body or externalenvironment2.CNS processes the information,determines appropriate response3. CNS issues commands to musclesand gland cells to carry out theresponse
2017‐10‐044Functional classes ofneuronsAfferent neuronInterneuronEfferent neuron1.Afferent (sensory) neuronsDetect stimuli and transmit the informationtoward the CNS2.Interneuronsin CNSConnecting neurons ‐ carry out integrativefunctions (make decisions)About 90% of our neurons are interneurons3.Efferent (motor) neuronsSends signals to muscles and/or gland cellsPeripheral Nervous System1.Sensory(afferent) divisionSomaticSignals from skin, muscles, bones, and jointsVisceralSignals from the viscera (heart, lungs,stomach, and urinary bladder)2.Motor(efferent) divisionSomaticCarries signals to skeletal musclesProduces muscle contractionsVisceral (autonomic nervous system)Signals to glands, cardiac, and smooth muscleInvoluntary responses arevisceral reflexes
2017‐10‐045Visceral motor division (autonomic nervous system)Subdivisions:1. Sympathetic divisionTends to arouse body for action (“fight or flight”)Accelerates heart beat and respirationInhibits digestive and urinary systems2. Parasympathetic divisionTends to have a calming effect (“rest and digest”)Slows heart rate and breathingStimulates digestive and urinary systems
2017‐10‐046SympatheticParasympatheticNote generaldifferences innerve organizationProperties of neurons

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