The Autonomic Nervous SystemIntroductionSlide 3Slide 4PowerPoint PresentationSlide 6Comparison of ANS & PNSSlide 8Slide 9Slide 10Slide 11Efferent Pathways and GangliaSlide 13Slide 14Slide 15Neurotransmitter EffectsSlide 17Overlap of Somatic & AutonomicDivisions of ANSSlide 20Slide 21Sympathetic DivisionSlide 23Slide 24Slide 25Role of Sympathetic DivisionSlide 27Parasympathetic DivisionAutonomic HomeostasisSlide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40Anatomy of ANSSlide 42Slide 43Slide 44Slide 45Slide 46Slide 47Cranial OutflowSlide 49Cranial OutflowSlide 51Slide 52Slide 53Slide 54Slide 55Slide 56Slide 57Slide 58Sacral OutflowSlide 60Slide 61Sympathetic DivisionSlide 63Slide 64Slide 65Slide 66Slide 67Slide 68Slide 69Slide 70Slide 71Slide 72Slide 73Slide 74Visceral ReflexesSlide 76Slide 77Slide 78Slide 79Slide 80Slide 81Slide 82Slide 83Slide 84Overview of the ANSEffectors of ANSThe Autonomic Nervous SystemChapter 15IntroductionThe Autonomic Nervous System (ANS) is the system of motor neurons that innervate the smooth muscle, cardiac muscle, and glands of the bodyBy controlling these effectors, the ANS regulates such visceral functions as … –Heart rate–Blood pressure–Digestion–UrinationIntroductionThe ANS is the general visceral motor division of the peripheral nervous system and is distinct from the general somatic motor and brachial motor divisions which innervate skeletal musclesIntroductionThe general visceral sensory system continuously monitors the activities of the visceral organs so that the autonomic motor neurons can make adjustments as necessary to ensure optimal performance of the visceral organsIntroductionThe stability of our internal environment depends largely on the autonomic nervous systemAutonomic nervous system(ANS) receives signals from visceral organsThe ANS makes adjustments as necessary to ensure optical support for body systemsComparison of ANS & PNSRecall that the somatic motor system innervates skeletal musclesEach somatic motor neuron runs from the central nervous system all the way to the muscle being innervated, and that each motor unit consists of a single neuron plus the skeletal muscle cells it innervatesTypical somatic motor axons are thick, heavily myelinated fibers that conduct nerve impulses rapidlyComparison of ANS & PNSComparison of ANS & PNSIn the somatic system–Cell bodies are within the central nervous system–Axons extend to the muscles they serve–Somatic motor fibers are thick, heavily myelinated Type A fibers that conduct impulses very rapidlyComparison of ANS & PNSIn the autonomic nervous system–The motor unit is a two neuron chain–The cell body of the first neuron, the preganglionic neuron, resides in the brain or spinal cord–Its axon, the preganglionic axon, synapses with the second motor neuron, the post- ganglionic neuron, in an autonomic ganglion outside the central nervous system–The postganglionic axon then extends to the effector organComparison of ANS & PNSCompare the one motor neuron of the somatic motor division with the two neuron chain of the autonomic nervous systemEfferent Pathways and GangliaAxons of most preganglionic neurons run from the CNS to synapse in a peripheral autonomic ganglion with a postganglionic neuronEfferent Pathways and GangliaAxons of postganglionic neurons run from the ganglion to the effectors (cardiac and smooth muscle fibers and glands)Efferent Pathways and GangliaPreganglionic axons are lightly myelinated thin fibersPostganglionic axons are even thinner and are unmyelinatedConduction though the autonomic chain is slower than through the somatic motorMany pre and postganglionic fibers are incorporated into spinal or cranial nerves for most of their courseEfferent Pathways and GangliaRemember that autonomic ganglion are motor ganglia, containing the cell bodies of motor neuronsThey are sites of synapse and information transmission from pre to postganglionic neuronsAlso note that the somatic motor division lacks ganglia entirelyNeurotransmitter EffectsAll somatic motor neurons release acetylcholine at their synapses with their effectors, skeletal muscle fibersThe effect is always excitatory, and if stimulation reaches threshold, the skeletal muscle fibers contactsNeurotransmitter EffectsNeurotransmitters released onto visceral effector organs by postganglionic autonomic fibers include–Norepinephrine secreted by most sympathetic fibers–Acetylcholine released by parasympathetic fibersDepending on the receptors present on the target organ, its response to these neuro- transmitters may be either excitation or inhibitionOverlap of Somatic & AutonomicHigher brain centers regulate and coordinate both somatic and visceral motor activitiesNearby spinal nerves and many cranial nerves contain both somatic and autonomic fibersMost of the body’s adaptations to changing internal and external conditions involve both skeletal activity and enhanced response of visceral organsDivisions of ANSThere are two division of the ANS–Parasympathetic–SympatheticGenerally the two divisions have chains of two motor neurons that innervate same visceral organs but cause essentially opposite effectsIf one division stimulates certain smooth muscle to contract or a gland to secrete, the other division inhibits that actionThrough this process of duel innervation the two systems counterbalance each otherDivisions of ANSThe sympathetic part mobilizes the body during extreme situations (such as fear, exercise or rage)The parasympathetic division allows us to unwind as it performs maintenance activities and conserves body energyDivisions of ANSBoth the sympathetic and parasympathetic divisions issue from the brain and spinal cordTwo neuron pathways are shown for both divisionsSolid lines indicate pre-ganglionic axons while broken lines indicate post-ganglionic axonsSympathetic DivisionThe sympathetic division is responsible for the “fight, flight, or fright” responseIts activity is evident during vigorous exercise, excitement, or emergenciesPhysiological changes like a pounding heart, fast and deep breathing, dilated eye pupils, and cold, sweaty skin are signs of the mobilization of the sympathetic division, which help us survive dangerSympathetic DivisionSympathetic responses prepare our bodies to cope with physiological