AUTONOMIC NERVOUS SYSTEM Dr Maha Hegazi Professor of

AUTONOMIC NERVOUS SYSTEM Dr. Maha Hegazi Professor of Physiology Faculty of Medicine King Abdul Aziz University Lecture 5 MAHA HEGAZI 1

Functions of the parasympathetic nervous system: Objectives: By the end of this lecture the student should be able to: • List the characteristics of the parasym. System. • Describe the parasympathetic functions of different body organs. • List the higher centers that control the MAHA HEGAZI 2 ANS

Functions of the parasympathetic NS Parasympathetic NS is characterized by: • It discharges during rest and sleep. • Its action is localized. • It has anabolic action (conserve body stores ). • It increases gastrointestinal secretion & motility i. e. secretomotor. MAHA HEGAZI 3

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-3 rd cranial nerve (Occulomotor nerve): Eye: 1 -Pupil constriction (by contraction of the sphincter muscle of the iris. 2 -Accompdation of the eye to near vision due to contraction of the ciliarymuscle. -7 th cranial nerve (Facial nerve): Sublingual & sublingual salivary glands: Increases its secretion of watery saliva ( large volume). Lacrimal glands: increases its secretion of tears -9 th cranial nerve (Glossopharyngeal nerve): Parotid salivary glands: Increases its secretion of watery saliva ( large volume). MAHA HEGAZI 5

10 th Cranial nerve (X) vagus nerve (supply viscera in the thorax & abdomen) Thorax Heart Ooooooooooo Lung *Decrease heart rate. *Bronchoconstriction. *Decrease force of contraction of atria. *Increase mucous secretion from bronchial glands. *VC of coronary blood vessels indirectly due to decreased cardiac work and O 2 demand. MAHA HEGAZI 6

Abdominal Viscera *Gall bladder: Contraction of the wall & relaxation of the sphincter. *GIT: Contraction of the wall & relaxation of the sphincter (increase its secretion & motility). *Pancreas: Increase insulin secretion. MAHA HEGAZI 7

Sacral division ( supply the pelvic organs ): *Urinary bladder: Contraction of the wall and relaxation of the internal sphincter. Uterus: variable depending on the stage of the menstrual cycle, the estrogen and progesterone hormones, and pregnancy. *Rectum: Contraction of the wall and Relaxation of the internal sphincter. *External genitalia -Vasodilatation of the blood vessels - MAHA HEGAZI induce errection. 8

Dual innervation • Almost all visceral organs are supplied by both sympathetic and parasympathetic divisions of the autonomic NS. • Which division predominate at any given time is determined by the body demands at that time. • The parasympathetic discharge to the heart is more powerful at rest (vagal tone) While the sympathetic discharge to the blood vessles is more potent at rest (sympathetic tone. MAHA HEGAZI 9

Structures supplied only by sympathetic nervous system: • Skin • sweat glands sympathetic cholinergic) • Piloerector muscle. • blood vessels all over the body except the penis. • Dilator pupillae muscle. • Blood vessels of the skeletal muscles sympahetic • • cholinergic. Adrenal medulla. Capsule of the spleen. MAHA HEGAZI 10

Structures supplied only by Parasympathetic nervous system: • Constrictor pupillae muscle. MAHA HEGAZI 11

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