Parasympathetic NS (craniosacral) Preganglionic neurons ………………………. Cranial...
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Transcript of Parasympathetic NS (craniosacral) Preganglionic neurons ………………………. Cranial...
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Parasympathetic NS (craniosacral)Preganglionic neurons……………………….Cranial outflow…. - occulomotor (III) - facial (VII) - glossopharyngeal (IX) - vagus (X)Sacral outflow…..2nd, 3rd and 4th sacral segments
Post ganglionic neurons …. terminal ganglia
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The parasympathetic division often produces antagonistic effects to sympathetic division through the release of acetylcholine from its post ganglionic fibers
Functions of Parasympathetic Nervous SystemFunctions of Parasympathetic Nervous System
1- Head & Neck:
Occulomotor Nerve (3rd cranial nerve): → Pupil constriction (miosis) → increase power of lens necessary for
near vision
Facial nerve (7th cranial nerve): A- Secretomotor & vasodilator to the submandibular & sublingual salivary glands B- secretion of lacrimal & nasal glands.
Glossopharynqeal nerve (9th cranial nerve): Secretomotor & vasodilator to parotid
gland.
Functions of Parasympathetic Nervous SystemFunctions of Parasympathetic Nervous System
Thorax & Abdomen are supplied by Vagus nerve (10th cranial nerve )
2- Thorax:
Heart: → Inhibition of all atrial properties (NO vagal supply to ventricles)
→ Decrease coronary flow & 02
consumption
Lungs: → Bronchial constriction → Dilatation of pulmonary blood vessels → Increase bronchial secretion.
Functions of Parasympathetic Nervous SystemFunctions of Parasympathetic Nervous System
(3) Abdomen: GIT: → Motor to esophagus, stomach, small intestine, proximal part of large intestine → Inhibitory to sphincters
→ Secretory to glands of stomach, small intestine, liver, pancreas
Gall bladder: → Motor to wall → Inhibitory to sphincters i.e. Evacuation of gall bladder.
Functions of Parasympathetic Nervous SystemFunctions of Parasympathetic Nervous System
(4) Pelvis: sacral outflow a) Defecation ++
b) Micturition: ++
c) MaIe genitalia: → Erection → Secretory to seminal vesicle & prostate
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OrganParasympathetic Response
"Rest and Digest"Sympathetic Response
"Fight or Flight"
Heart Decreased heart rateCardiac output decreases
Increased rate and strength of contraction Cardiac output increases
Lung Bronchioles Constriction Dilation
Liver Glycogen No effectGlycogen breakdown
Blood glucose increases
Fat Tissue No effectBreakdown of fat
Blood fatty acids increase
Basal Metabolism No effect Increases ~ 2X
StomachIncreased secretion of HCl & digestive
enzymesIncreased motility
Decreased secretionDecreased motility
IntestineIncreased secretion of HCl & digestive
enzymesIncreased motility
Decreased secretionDecreased motility
Urinary bladderRelaxes sphincter
Detrusor muscle contractsUrination promoted
Constricts sphincterRelaxes detrusor
Urination inhibited
RectumRelaxes sphincter
Contracts wall musclesDefecation promoted
Constricts sphincterRelaxes wall musclesDefecation inhibited
EyePupils constrict
Adjusts for near visionPupils dilate
Adjusts for far vision
Male Sex Organs Promotes erection Promotes ejaculation 8
Chemical transmitters in autonomic nervous system
• Acetylcholine• Noradrenaline (Norepinephrine)
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Acetylcholine Sites of release of acetylcholine• All preganglionic autonomic fibers (sympathetic ¶ sympathetic )• preganglionic sympathetic fibers to suprarenal medulla• All postganglionic para sympathetic fibers• postganglionic sympathetic fibers to sweet glands and blood vessels
of skeletal muscle ( VD)Removal of acetylcholineIt is split into acetate & choline by acetylcholine esterase True acetylcholine esterase → cholinergic nerve endings Pseudo acetylcholine esterase → in plasma
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Cholinergic receptors
Nicotinic receptors -autonomic ganglia -skeletal muscles ( motor end plate) -suprarenal medulla
Muscarinic receptors -viscera supplied by postganglionic para sympathetic
fibers -sweet glands and blood vessels of skeletal muscle (
sympathetic cholinergic fibers)
Nor adrenaline (Norepinephrine)Sites of release of Noradrenaline All postganglionic sympathetic fibers except
fibers to sweet glands and blood vessels of skeletal muscle
Fate of Noradrenaline1. Re-uptake into the adrenergic nerve endings2. Diffusion away into the body fluids & plasma3. Destruction by• MAO ( monoamin oxidase) • COMT ( catechol-O –methyl transferase)
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Adrenergic receptors
Alpha receptorsAlpha 1 and alpha 2
Alpha 1 →Excitatory ( intracellular Ca++ )• Vasoconstriction • Contraction of sphincter of GIT, dilator pupillea ,
spleniccapsule, seminal vesicles and vas deferensAlpha 2 → inhibitory to intestinal wall ( c-AMP)
Beta receptorsBeta 1 → excitatory, heart & metabolic action
Bate 2 → inhibitory,smooth muscles of bronchi, urinary bladder, intestine, VD of skeletal muscle ( c-AMP)