AUTONOMIC NERVOUS SYSTEM Two major subdivision Parasympathetic cranio sacral outflow Sympathetic thoraco lumbar out flow Responsible for the visceral control Sometimes referred to as vegetative control ID: 1038738
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1. NERVOUS SYSTEMAUTONOMIC NERVOUS SYSTEM
2. AUTONOMIC NERVOUS SYSTEMTwo major subdivisionParasympathetic cranio-sacral outflowSympathetic thoraco-lumbar out flowResponsible for the visceral controlSometimes referred to as vegetative controlProvides motor innervation to glands, heart and other organs having smooth musclesPart of motor division of NS Controlled from SC, medulla and hypothalamusActivity is induced by peripheral afferent neuronsTherefore sensory NS is an integral part of ANSCRANIOSACRALTHORACOLUMBAR
3. DIVISIONS IN AUTONOMIC NERVOUS SYSTEMCore of ANS is HypothalamusReceives specific afferent inputsControls motor activity necessary for homeostasisParasympathetic system is served byRostral and medial hypothalamusPreoptic areaAnterior, dorsal and dorsomedial nucleiMamillary bodiesSympathetic system is supported byPosterior and lateral hypothalamic nucleiVMN is shared by both SS and PSSHigher centers (Eg:cerebrum & cerebellum) modify the visceral control of hypothalamusSimilarly hypothalamus modifies the activities of lower centers in brain stem (Eg: resp. centre)
4. PARASYMPATHETIC DIVISIONComposed of axons within the cranial nervesIII (Occulomotor)VII (Facial)IX (Glassopharyngeal) - X (Vagus) - Structures of headThorasic and abdominal viscera
5. SYMPATHETIC DIVISIONReceives preganglionic fibers only from thorasic and upper lumbar spinal cordEach preganglionic neuron exercises control over many ganglionic neuronsNot only in one but many ganglionsTherefore there is great divergence of impulsePost ganglionic fibers from cervical ganglion joinTrigeminalFacialGlassopharyngealVagusAccessoryHypoglossal nervesAlso contribute to1st, 2nd and 3rd cervical spinal nervesEach spinal nerve carries several sympathetic fibers
6. PERIPHERAL EFFERENT DIVISION OF THE AUTONOMIC NERVOUS SYSTEMFollow a two neuron pathwayCell bodies of first neuron in CNS – preganglionic neuronAxons of these neurons terminate on ganglionic neurons located at different distances from CNSGanglionic neurons of SS are aggregated in “para vertebral ganglia”Ganglionic neurons of PSS are located in the effectorsTherefore the post ganglionic fibers of PSS are shorterAdrenal medullary innervation does not follow two neuron pathwayBecause adrenal medullary cells are modified neurons without axonsTherefore adrenal medullary cells themselves are ganglionic cells and there are no post ganglionic fibersPreganglionic fiber
7. AUTONOMIC REFLEX ARC
8. NEUROTRANSMITTERS OF THE ANSAcetyl choline – cholinergicORNor Epinephrine - adrenergicAll the pre-ganglionic fibers in SS and PSS are cholinergicTherefore Ach / Ach like substances when applied to ganglia could excite both SS and PSSAll post-ganglionic fibers of PSS are also cholinergicTherefore Ach is the Para sympathetic transmitterMost post-ganglionic sympathetic fibers are adrenergicTherefore norepinephrine is the Sympathetic transmitterPost-ganglionic sympathetic fibers to Sweat glandsPilo-erector musclesFew blood vesselsSympathomimetics-Mimic the activity of SSSympatholytics – inhibit the activity of sympathetic systemParasympathomimetics and parasympatholyticsCHOLINERGIC
9. FUNCTIONS OF THE AUTONOMIC NERVOUS SYSTEMSeveral organs have both sympathetic and parasympathetic innervationUsually when one system excites the other inhibits the same organFinal activity of such organs is the net balance between opposing actions of SS and PSSSS and PSS act as visceral flexors and extensors
10. FUNCTIONS OF THE AUTONOMIC NERVOUS SYSTEMThe SS along with adrenal medulla is involved in emergency reactionsAlso called flight or fight reactionEstablishes optimal conditions for defense of an organism in life threatening situationsReactions includeVasoconstriction in skin vasodilatation in musclesCOP is increasedCoronary vasodilatationElevated blood glucoseIncreased metabolic ratePiloerectionMydriasis – Pupillary dilatationDecreased GI motilityBroncho dilatationContraction of spleen
11. PSS – Vasodilatation and secretionSS – Vasoconstriction and Increased mucusEffects of Autonomic Nervous system -LACRIMAL GLANDS
12. Effects of Autonomic Nervous system IRIS MUSCLES - PUPILPSS – Constriction (Miosis) SS – Dilatation (Mydriasis)
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14. Effects of Autonomic Nervous system CILIARY MUSCLESPSS – contraction – accommodation for near visionSS – doubtful
15. Effects of Autonomic Nervous System NICTITATING MEMBRANESS – Retraction PSS – NO INNERVATION
16. Effects of Autonomic Nervous System EYE LIDSSS – RaisedPSS – NO EFFECT
17. Effects of Autonomic Nervous System Sub –mandibular & sub-lingual salivary glandsPSS – Vasodilatation & secretion of large volumesSS – Expulsion but no increase in secretion
18. Effects of Autonomic Nervous System Parotid Salivary glandsPSS – increased secretionSS – increase in organic matter
19. Effects of Autonomic Nervous SystemCoronary Blood VesselsPSS – Negligible influenceSS – Increased Blood flow
20. Effects of Autonomic Nervous SystemSmooth Muscles in GIT, Rumen & Gall BladderPSS – ContractionsSS – Inhibition
21. Effects of Autonomic Nervous SystemPyloric SphincterPSS – Contractions in dog and catSS –Inhibition But relaxation in cow
22. Effects of Autonomic Nervous SystemReticulo-Omasal SphincterPSS – RelaxationSS –Contraction
23. Effects of Autonomic Nervous SystemGastric Glands PSS – SecretionSS –Inhibition
24. Effects of Autonomic Nervous System PancreasPSS –secretionSS – Inhibition
25. Effects of Autonomic Nervous System LiverPSS –No effectSS – Glycogenolysis & Bile secretion
26. Effects of Autonomic Nervous System Mammary GlandPSS –No effectSS – Inhibition of milk let down
27. Effects of Autonomic Nervous SystemUrinary BladderPSS:Smooth Muscles contractSphincter relaxedSS: Smooth Muscles InhibitedSphincter contracted
28. Effects of Autonomic Nervous SystemColonPSS:Smooth Muscles contractAnal sphincter relaxedSS: Smooth Muscles InhibitedAnal sphincter contracted
29. Effects of Autonomic Nervous SystemPenisSS:Vasoconstriction & EjaculationPSS- Vasodilatation & Penile erection
30. Effects of Autonomic Nervous SystemClitorisPSS- Vasodilatation & erectionSS:Vasoconstriction
31. Effects of Autonomic Nervous SystemUterus and OviductPSS- Vasodilatation & inhibition of smooth musclesSS:Vasoconstriction & increased motility
32. Effects of Autonomic Nervous SystemVaginaPSS- Vasodilatation, mucus secretion & tightening around penisSS:Vasoconstriction & sexual satiety
33. Effects of Autonomic Nervous SystemTestis and KidneyPSS- No innervationSS:Vasoconstriction
34. Effects of Autonomic Nervous SystemProstate glandPSS- Vasodilatation & secretionSS:Vasoconstriction & inhibition of secretion
35. Effects of Autonomic Nervous SystemCutaneous Blood VesselsPSS- No innervationSS:Vasoconstriction
36. Effects of Autonomic Nervous SystemPiloerrector MusclesPSS- No innervationSS:Contraction
37. Effects of Autonomic Nervous SystemSweat GlandsPSS- No innervationSS:Secretion
38. Effects of Autonomic Nervous SystemBlood sugarPSS- No innervationSS:Elevation