L4 - Autonomic Nervous System PDF

Lecture 4 AUTONOMIC NERVOUS SYSTEM Color Index: Main text Boys' Slides Girls' Slides...

Lecture 4 AUTONOMIC NERVOUS SYSTEM Color Index: Main text Boys' Slides Girls' Slides Important Dr's Notes Extra Editing File OBJECTIVES Define the autonomic nervous system. Describe the structure of autonomic nervous system. Trace the preganglionic & postganglionic neurons in both sympathetic & parasympathetic nervous system. Enumerate in brief the main effects of sympathetic & parasympathetic system.  Nervous System Peripheral Central Nervous Nervous System System Spinal cord Autonomic Nervous Somatic Nervous System brain system (Voluntary control) (Involuntary control) Sensory Motor Sympathetic Nervous System Parasympathetic Nervous System we will talk about this part Autonomic Nervous System Helpful Video Concerned with the innervation and control of involuntary structures: visceral organs, smooth & cardiac muscles and glands Along with the endocrine system, its primary function is homeostasis of the internal environment. Regulated (controlled) by hypothalamus. Unlike the somatic nervous system, the efferent pathway of the autonomic nervous system is made up of two neurons called as preganglionic and postganglionic neurons. The cell bodies of the preganglionic neurons are present in the brain and spinal cord. Their axons synapse with the postganglionic neurons whose cell bodies are present in the autonomic ganglia Located both in the central and peripheral nervous systems.  Symapthetic Activated during exercise, excitement and emergencies. Parasympathetic Concerned with conserving energy. Both divisions operate in conjunction with one or another Note 438: the cause of preganglionic (white) and postganglionic (grey) fibers having different colors (have antagonistic control over is the myelin sheath that the preganglionic fibers the viscera) to maintain a stable (white) are sheeted with. Myelin helps isolate internal environment. preganglionic fibers for faster transportation.  Sympathetic Parasympathetic Iris of the eye (pupil) Dilates (wider) Constricts Ciliary of the eye Relaxes Contracts Salivary gland Reduces secretions Increases secretions Lacrimal gland Reduces secretions Increases secretions Increases rate and Decreases rate and Heart force of contraction force of contraction Bronchi Dilates Constricts Gastrointestinal tract Decreases motility Increases motility Sweat glands Increases secretions No effect Erection Pili (muscle Contracts No effect attachedto the hair) Adrenaline Released Inhibited Bladder Relaxes Contracts Sympathetic Division 1- Preganglionic Neurons: Located in the lateral gray horn of T1- L2 segments of spinal cord (ThoracoLumbar Outflow). Outflow: the passage of impulses outwardly from the central nervous system. Important Note (439): Sympathetic neurons are only found in the spinal cord. 2- Postganglionic ganglia: Located nearer to the central nervous system as: 1- Prevertebral is the celiac and mesenteric (in front of vertebral). 2- Paravertebral forming sympathetic chain (next to parallel). Paravertebral Ganglia They are interconnected to form 2 sympathetic chains, one on each side of vertebral column Number of ganglia: Three in cervical part of chain. Eleven to twelve in thoracic part. Four in lumbar & sacral parts each. The chains end into a common 'ganglion impar' in front of coccyx. Impar means one ganglion Preganglionic Fibers Girls' Slides Run in the ventral roots of the spinal nerve. Travel through the spinal nerve, and then join the sympathetic chain via white rami communicans (WRC.) Singular *ramus*, plural *rami*.  Preganglionic Fibers - Within the Sympathetic Chain, these fibers may: Synapse with cells of the corresponding paravertebral 1 ganglion located in the sympathetic chain. Postganglionic neurons are cells of the corresponding paravertebral ganglion; postganglionic axons leave the sympathetic chain and join the spinal nerve (via grey ramus cummincans) (GRC) to supply structures in thorax + blood vessels & sweat glands. Check the photo on the right to have a better understanding 1 Preganglionic Fibers Cont… - Within the Sympathetic Chain, these fibers may: Ascend or descend to synapse with neurons 2 (postganglionic) of paravertebral ganglia located in sympathetic chain. Postganglionic neurons are cells of this particular paravertebral ganglion: postganglionic axons leave the sympathetic chain & join the spinal nerve corresponding to this ganglion to supply structures in head & thorax + blood vessels & sweat glands. 2 Check the photo on the right to have a better understanding 2 Preganglionic Fibers Cont… - Within the Sympathetic Chain, these fibers may: 3 Leave the sympathetic chain (without synapse) to reach coeliac & superior or inferior mesenteric ganglia (around branches of abdominal aorta) to synapse with their neurons (postganglionic). Postganglionic neurons are cells of coeliac, superior & inferior mesenteric plexuses. Postganglionic axons supply abdominal & pelvic viscera. Check the photo on the right to have a better understanding 3 Sympathetic Nervous System Anatomy Parasympathetic Division Preganglionic neurons located in: Nuclei of the 3rd, 7th, 9th, and 10th Cranial Nerves of the brainstem (cranial outflow). The lateral gray horn of the S2-S4 segments of the Spinal Cord (sacral outflow). Preganglionic fibers from cranial outflow are carried by 3rd, 7th, 9th & 10th cranial nerves and terminate in ciliary, pterygopalatine, submandibular, otic & peripheral ganglia. Postganglionic fibers innervate organs of the head, neck, thorax, and abdomen. Preganglionic fibers from sacral outflow are carried by pelvic splanchnic nerves to peripheral ganglia in pelvis where they synapse. Postganglionic fibers innervate organs of the pelvis and lower abdomen. Parasympathetic Boys' Nervous System Slides Preganglionic parasympathetic neurons: 1 Cells located in the brainstem: Preganglionic axons leave the brainstem and join: Third cranial nerve to synapse with cells of ciliary ganglion. Postganglionic neurons supply sphincter pupillae & ciliary muscles. Seventh cranial nerve to synapse with the cells of pterygopalatine & submandibular ganglia. Postganglionic neurons of pterygopalatine gangila supply lacrimal, nasal & palatine gland. While the submadibular gland supply submandibular & sublingual salivary glands. Ninth cranial nerve to synapse with cells of otic ganglion. Postganglionic neurons supply parotid salivary gland. Tenth cranial nerve to synapse with cells of peripheral ganglia. Postganglionic neurons supply structures in the thorax & abdomen. Parasympathetic Boys' Nervous System Slides Preganglionic parasympathetic neurons: 2 Cells located in 2nd, 3rd & 4th sacral segments of spinal cord: Preganglionic axons leave the spinal cord and join: Corresponding sacral spinal nerves to reach peripheral ganglia in the pelvis where they synapse. Postganglionic neurons are cells of peripheral ganglia. Postganglionic axons supply pelvic viscera. Comparsion Between Sympathetic And Parasympathetic Division  MCQs 1 The postganglionic ganglias of the sympathetic nervous system is located at: A) Brainstem B) Thoracic C) Sacral segments D) Sympathetic 2 segments chain Which of the following cranial nerves contain a parasympathetic neuron? A) 5th B) 7th C) 2nd D) 11th 3 A) Dilated iris of Which of the following is a parasympathetic effect? B) Dilated bronchi C) Decrease in GIT D) Decreased heart 4 the eye motility rate Preganglionic fibers get through sympathetic chain via: B) White Ramus A) Spinal nerve C) Ventral root D) GRC 5 communicans Where do parasympathetic fibres originate? A) The B) The cranial and D) Coeliac & thoracolumbar C) Head and Neck sacral regions Mesenteric ganglia spinal region 1-D 2-B 3-D 4-B 5-B  Leaders Nisreen Alotaibi Omar Alattas MEMBERS Shaden Alotaibi Abdulhadi Alqahtani Danah Khallaf Turki Alanzi Elaf Alshamlan Talal Alrobaian Jana Alahaideb Abdulmalik Aldafs Dana Alotaibi Ahmad Addas Noorah Alkhilaiwi Salman AlHakeem Orjwan Alharthi Ziyad Bukhari Lana Alfouzan [email protected]