_ch_14_lecture_presentation.ppt - Autonomic nervous system...

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CHAPTER 14Autonomic nervous system
Autonomic Nervous System (ANS)ANS consists of motor neurons thatInnervate smooth and cardiac muscle, andglandsMake adjustments to ensure optimal supportfor body activitiesOperate via subconscious controlAlso calledinvoluntary nervous systemorgeneral visceral motor system
Figure 14.1Place of the ANS in the structural organization of the nervous system.Central nervous system (CNS)Peripheral nervous system (PNS)Sensory (afferent)divisionMotor (efferent) divisionSomatic nervoussystemAutonomic nervoussystem (ANS)SympatheticdivisionParasympatheticdivision
Somatic Versus Autonomic NervousSystemsBoth have motor fibersDiffer inEffectorsEfferent pathways and gangliaTarget organ responses to neurotransmitters
EffectorsSomatic nervous systemSkeletal musclesANSCardiac muscleSmooth muscleGlands
Efferent Pathways and GangliaSomatic nervous systemCell body in CNS; thick, myelinated, group Afiber extends in spinal or cranial nerve toskeletal muscleANS pathway uses two-neuron chain1. Preganglionic neuron(in CNS) has a thin,lightly myelinatedpreganglionic axon.2. Postganglionic neuroninautonomic ganglionoutside CNS hasnonmyelinatedpostganglionic axonthatextends to effector organ
Neurotransmitter EffectsSomatic nervous systemAll somatic motor neurons releaseacetylcholine (ACh)Effects always stimulatoryANSPreganglionic fibers release AChPostganglionic fibers release norepinephrineor ACh at effectorsEffect is either stimulatory or inhibitory,depending on type of receptors
Figure 14.2Comparison of motor neurons in the somatic and autonomic nervous systems.Cell bodies in centralnervous systemPeripheral nervous systemNeurotransmitterat effectorEffectororgansEffectSOMATICNERVOUSSYSTEMAUTONOMIC NERVOUS SYSTEMSYMPATHETICPARASYMPATHETICSingle neuron from CNS to effector organsHeavily myelinated axonAChSkeletalmuscleStimulatoryTwo-neuron chain from CNS to effector organsLightly myelinatedpreganglionic axonsGanglionNonmyelinatedpostganglionic axonEpinephrine andnorepinephrineAChAChAdrenal medullaBlood vesselLightly myelinatedpreganglionic axonGanglionAChNonmyelinatedpostganglionicaxonAChSmooth muscle(e.g., in gut), glands,cardiac muscleStimulatoryor inhibitory,dependingon neuro-transmitterand receptorson effectororgansAcetylcholine (ACh)Norepinephrine (NE)NE++
Divisions of the ANSSympathetic divisionParasympathetic divisionDual innervation~ All visceral organs served by both divisions,but cause opposite effects
Role of the Parasympathetic DivisionPromotes maintenance activities andconserves body energyDirects digestion, diuresis, defecationAs in person relaxing and reading after amealBlood pressure, heart rate, and respiratoryrates are lowGastrointestinal tract activity highPupils constricted; lenses accommodated forclose vision

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Term
Spring
Professor
kim
Tags
sympathetic division, sympathetic trunk

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