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Regulating Systems Week 3

Regulating Systems Week 3. Dr. Walid Daoud As. Professor. Divisions of Autonomic Nervous System. Functions of Sympathetic N.S. ___________________________. 1-Head and neck: . Eye: - Motor to dilator pupillae muscle. - Relaxation of ciliary muscle.

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Regulating Systems Week 3

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  1. Regulating SystemsWeek 3 Dr. Walid Daoud As. Professor

  2. Divisions of Autonomic Nervous System

  3. Functions of Sympathetic N.S.___________________________ 1-Head and neck: . Eye: - Motor to dilator pupillae muscle. - Relaxation of ciliary muscle. - Vasoconstriction of conjunctival vessels. - Decrease tears secretion.

  4. Functions of Sympathetic N.S.__________________________ . Skin: - Secretory to sweat glands. - Vasoconstriction of cutaneous vessels. - Contraction of piloerector muscle . Salivary glands: Trophic secretion of saliva. . Cerebral circulation; Increase cerebral blood flow due to an increase in arterial blood pressure.

  5. Functions of Sympathetic N.S.___________________________ 2- Thoracic viscera: . Heart: - Increase all properties of the heart. - Vasodiltation of coronary blood vessels. . Lungs: - Dilatation of all bronchial tree. - Vasoconstriction of pulmonary vessels.

  6. Functions of Sympathetic N.S.____________________________ 3- Abdominal viscera: . GIT:Inhibition of smooth muscles of stomach to proximal part of large intestine. Vasoconstriction to their arterioles. Motor to sphincters. . Liver:Stimulation of glycogenolysis. . Spleen:Contraction of splenic capsule. . Adrenal medulla:Secretes adrenaline and noradrenaline.

  7. Functions of Sympathetic N.S.____________________________ 4- Pelvic viscera: . GIT:Inhibition of plain muscles of distal part of large intestine and rectum and contraction of internal anal sphincter. . Urinary bladder:Inhibition of the wall and contraction of internal urethral sphincter. . Male genital organs:Contraction of vas deference, seminal vesicle and prostate and vasoconstriction of blood vessels.

  8. Functions of Parasympathetic N.S._____________________________ 1- Head and neck: . Oculomotor nerve III: - Motor to constrictor pupillae muscle. - Contraction of ciliary muscle. . Facial nerve VI: - Secretomotor and vasodilator to the submandibular and sublingual salivary glands and lacrimal glands. . Glossopharyngeal nerve IX: Secretomotor and vasodilator to parotid.

  9. Functions of Parasympathetic N.S._____________________________ 2-Thoracic & abdominal viscera: Vagus X . Heart: - Inhibit all properties of atrial muscles only. - Decrease coronary blood flow and O2 used . Lungs: - Constriction of airway & dilatation of vessels - Stimulation of bronchial glands. . GIT and gall bladder: - Motor to wall & inhibitory to sphincters, down to proximal part of large intestine.

  10. Functions of Parasympathetic N.S._____________________________ 3- Pelvic viscera: . Defecation. . Micturation. . Erection in males. . Vasodilatation of female genital organs.

  11. Chemical Transmission at Autonomic Junctions____________________________ Transmission at the synaptic junctions is chemically mediated between: - Pre- and postganglionic neurons. - Postganglionic neurons and autonomic effector organs. Chemical transmitters: Acetylcholine and noradrenaline.

  12. Acetylcholine____________________________ Chemical transmitter released by cholinergic fibers to stimulate cholinergic receptors. Sites of secretions: - All preganglionic fibers: Sympathetic Parasympathetic Suprarenal medulla - All postganglionic parasympathetic fibers. - Postganglionic sympathetic fibers to sweat glands & blood vessels of skeletal muscles.

  13. Acetylcholine__________________________ Synthesis: Choline Acetyl – CoA----------------→ Acetylcholine Acetyl transferase Acetylcholine is stored in clear vesicles in the termination of cholinergic fibers

  14. Acetylcholine____________________________ Release: The action potential causes release of acetylcholine from the vesicles by exocytosis. Removal: Acetylcholine Acetylcholine ----------------→ Choline + Acetate esterase

  15. Noradrenaline (Norepinephrine)____________________________ Chemical transmitter released by adrenergic fibers to stimulate adrenergic receptors. Sites of secretion: Postganglionic sympathetic fibers except: - Secretory fibers to sweat glands. - Vasodilator cholinergic fibers to blood vessels of skeletal muscles.

  16. Noradrenaline (Norepinephrine)____________________________ Synthesis: In terminal ending of adrenergic nerve fiber and secreted from adrenal medulla with adrenaline. Release: Nerve impulse stimulate adrenergic fibers to release adrenaline by exocytosis.

  17. Noradrenaline (Norepinephrine)____________________________ Removal: 1- Re-uptake into the adrenergic nerve endings (50-80%). 2- Diffusion away from the nerve ending into body fluids. 3- Destructed by enzymes: .Monoamine oxidase (MAO) on mitochondria .Catechol-0-methyl-transferase (COMT) in all tissues

  18. Receptors of Effector Organs___________________________ 1- Cholinergic receptors: . Muscarinic receptors: - All postganglionic parasympathetic NS - Postganglionic cholinergic sympathetic NS . Nicotinic receptors: Autonomic ganglia. 2- Adrenergic (Alpha & Beta) receptors: - On surface of effector organ (postsynaptic). - On postganglionic nerve ending (presynaptic).

  19. Actions of Post-synaptic Adrenergic Receptors________________________________________ Alpha receptors: 1-Vasoconstriction. 2-Contraction of plain muscles of: Dilator pupillae muscle, sphincters of GIT, spleen, internal urethral sphincter, seminal vesicles and vas deferens. 3-Inhibition of plain muscles of intestine.

  20. Actions of Post-synaptic Adrenergic Receptors________________________________________ Beta receptors: 1-Vasodilatation of skeletal blood vessels (β2) 2-Inhibition of plain muscles of: Bronchi, GIT, urinary bladder and uterus. 3-Cardiac acceleration and increased force of contraction of the heart (β1). 4-Lipolysis (β1).

  21. Comparison Between Sympathetic and Parasympathetic Functions____________________________ See Page 16 and 17 in the Chapter of Regulating Systems

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