Physiology Lecture 8 2024 PDF

2024 PbJSIOIOiJ lecture 8 Dr. M.M  Origin & relay of parasympathetic nervous system Origin Relay Effector organ  Edinger westphal Oculomotor n. nucleus...

2024 PbJSIOIOiJ lecture 8 Dr. M.M  Origin & relay of parasympathetic nervous system Origin Relay Effector organ  Edinger westphal Oculomotor n. nucleus in  Ciliary ganglion  Eye. midbrain a. Greater  Spheno-palatine  Lacrimal gland. superficial ganglion.  Nose. petrosal Facial nerve  Sup. Salivary  Submandibular nucleus in pons.  Spheno- & sublingual b. Chorda mandibular gland. tympani ganglion.  ant. 2/3 of tongue.  Inferior salivary  Parotid gland. Glossopharyngeal  Otic ganglion. nucleus in  Posterior 1/3 of nerve medulla. tongue.  Dorsal motor  Terminal  All chest and Vagus nerve nucleus of vagus ganglion. abdomen. in medulla  Bladder. Pelvic nerve  S2,3,4 segment  Terminal (nervous  Rectum. of spinal cord ganglion. erigenus.)  Sex organ. DR. M. M. Page| 1 DR. M. M. Page| 2  Functions of Parasympathetic Supply 1) Oculomotor Nerve: Origin  Edinger Westphal nucleus in midbrain. Relay  Ciliary ganglion. a. Contraction of constrictor pupillae ms → narrowing of pupil (miosis). Functions b. Contraction of ciliary ms → ↑ convexity of lens → helps eyes to see near objects → accommodation to near vision.  In near vision e.g. during reading:  Parasympathetic stimulation is important to decrease size of pupil NB to decrease amount of light entering eye & increases lens power to focus the image of object on retina of eye. DR. M. M. Page| 3  2) Facial Nerve Origin  Superior salivary nucleus in the pons  Greater superficial petrosal branch→ Sphenopalatine ganglion. Relay  Chorda tympani branch → Submandibular ganglion. a- Greater superficial petrosal nerve:  Vasodilatation. Lacrimal glands  Secretion of tears. Mucous membrane  Vasodilatation. of nose, soft palate  Secretion of mucus. & pharynx Functions b- Chorda tympani nerve:  Vasodilatation. Submandibular &  True salivary secretion (large in volume, sublingual salivary watery, rich in electrolyte and poor in glands enzymes). MM of anterior  Vasodilatation. 2/3 of tongue &  Mucous secretion floor of mouth DR. M. M. Page| 4  3) Glosso-pharyngeal Nerve: Origin  Inferior salivary nucleus in medulla oblongata. Relay  Otic ganglion 1. Parotid salivary gland :  Vasodilatation Functions  True salivary secretion. 2. Mucus membrane of posterior 1/3 of tongue & floor of mouth:  Vasodilatation  Parasympathetic supply to head & neck includes the functions of: 1. Oculomotor nerve. NB 2. Facial nerve. 3. Glossopharyngeal nerve. DR. M. M. Page| 5  4) Vagus (wandering) Nerve:  Origin:  Dorsal motor nucleus of vagus in medulla oblongata.  Relay:  Terminal ganglia.  Functions: A) Thorax: a. It decrease all cardiac properties as heart rate, force of contraction, conductivity and excitability →↓es the effectiveness of heart as a pump. b. Coronary vessels : Heart:  Direct effect → vasodilatation.  Indirect effect → vasoconstriction because it inhibits cardiac work with decreased metabolites.  Net result : VC (decreased coronary blood flow). a. Contraction of smooth ms of the bronchi → bronchoconstriction. b. Stimulate the mucus secretion of the air passages. Lungs: c. Vasodilatation of the pulmonary blood vessels. NB:  Vagus nerve supplies the atria only and does not supply the ventricles. DR. M. M. Page| 6  B) Abdomen:  Contraction of walls.  relaxation of sphincters. GIT  help both digestion and evacuation of GIT contents i.e. helps deglutition, GIT motility (peristalsis).  Gastric glands→ ↑ gastric juice secretion (rich in HC1). Glands  Bruner's glands in duodenum→↑ alkaline mucus secretion.  Pancreas: stimulates both endocrine and exocrine secretions Liver  ↑ hepatic bile flow.  Contraction of wall. Gall bladder  relaxation of sphincter of Oddi  help its evacuation of bile. Blood vessels  Vasodilatation. DR. M. M. Page| 7  5) Pelvic Nerve (nervous erigenus) : Origin  Sacral segments (2nd, 3rd, 4th) of spinal cord. Relay  Terminal ganglia. 1) Urinary bladder :  Contraction of wall.  relaxation of internal urethral sphincter  help micturition. 2) Rectum :  Contraction of wall Functions  relaxation of internal anal sphincter  Help defecation. 3) Sex organs :  VD of blood vessels of pelvic viscera including that of sex organs → erection of the penis, clitoris and congestion of the labia.  It ↑ the secretions from the seminal vesicles, prostate. N.B.  The external anal and urethral sphincters are voluntary ms supplied by the somatic spinal pudendal nerve. DR. M. M. Page| 8  Notes :  Most organs have a double nerve supply (sympathetic and parasympathetic).  Some organs are supplied only by one division of autonomic N.S : Sympathetic supply only Parasympathetic supply only 1) Dilator pupillae muscle 1) Constrictor pupillae muscle 2) Muller's muscle. 2) Upper esophagus. 3) Cutaneous effectors (skin) 3) Glands of stomach. 4) Ventricles of heart. 5) Spleen 6) supra renal medulla  The relation between sympathetic and parasympathetic NS may be:  One system increases the function & 2nd decreases the functions  e.g. Heart rate: Antagonistic  sympathetic increases HR  while parasympathetic : decreases HR  During salivary secretion : Synergistic  Parasympathetic secretes water and electrolytes.  Sympathetic secretes enzymes.  During sexual intercourse : Cooperative  Parasympathetic causes erection.  Sympathetic causes ejaculation. DR. M. M. Page| 9 Summary of the functions of sympathetic and parasympathetic N.S. DR. M. M. P a g e | 10