Lecture (4) AUTONOMIC NERVOUS SYSTEM (ANS) .pdf
- 1. AUTONOMIC NERVOUS SYSTEM (ANS) Foundation block - Anatomy - Lecture 4
- 2. Color guide : Only in boys slides in Green Only in girls slides in Purple important and doctors note in Red Extra information in Blue Objectives At the end of the lecture, the students should be able to: ● 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.
- 3. Autonomic Nervous System Concerned with the innervation and control of Involuntary structures: visceral organs, smooth & cardiac muscles and glands. Note: Hypothalamus controls both of Autonomic system + Endocrine system. ● Function: maintain homeostasis of the internal environment along with the Endocrine system. ● Located: both in the central and peripheral nervous systems. ● Regulated: (controlled) by Hypothalamus.
- 4. Autonomic Nervous System Preganglionic Neuron Postganglionic Neuron Autonomic Ganglion Preganglionic Axon Postganglionic Axon Somatic Motor Neuron Dorsal Root Ventral Root 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 located in the brain and spinal cord. Their axons synapse with the postganglionic neurons whose cell bodies are located in the autonomic ganglia. Note: before the fibers reach the target, it should first pass by the autonomic ganglion and synapse. Note: slide was only found in girls slides
- 5. Based on the anatomical, physiological and pharmacological characteristics, the autonomic nervous system is divided into: ▪ Sympathetic: Activated during exercise, excitement, and emergencies. “fight or flight”. ▪ Parasympathetic: Concerned with conserving energy. “rest and digest” Autonomic Nervous System Both divisions operate in conjunction with one another (have antagonistic control over the viscera) to maintain a stable internal environment Note: slide was only found in girls slides
- 6. Autonomic Nervous System Sympathetic Parasympathetic -Preganglionic neuron is in the CNS. -The Preganglionic fiber(axon) is shorter. -The Postganglionic neuron is in the PNS. and far from the target. -The Postganglionic fiber (axon) is longer. -Preganglionic neuron is in the CNS. -The Preganglionic fiber(axon) is longer. -The Postganglionic neuron is in the PNS and close to the target -The Postganglionic fiber(axon) is shorter. Note: The cause of preganglionic (White) and postganglionic (Grey) fibers having different colors is the Myelin sheath that the preganglionic fibers (white) are sheeted with. Myelin helps isolate preganglionic fibers for faster transportation. (اﺳﺮع وﯾﻮﺻﻞ اﻛﺜﺮ ﻣﻌﺰول ﺗﺨﻠﯿﮫ ) Postganglionic neuron Postganglionic neuron Preganglionic neuron Preganglionic neuron Short Preganglionic Fiber (White) Long Postganglionic Fiber (Grey) Long Preganglionic Fiber Short Postganglionic Fiber Note: slide was only found in girls slides
- 7. Sympathetic Nervous System Preganglionic neuron :Cells of lateral horn of spinal cord (T1 – L2) Preganglionic fiber(axon):Short axon Postganglionic neuron : located in : 1-Cells of sympathetic chain 2-Cells of plexuses surrounding abdominal (Coeliac, superior & inferior mesenteric) Postganglionic fiber (axon): Long axon Preganglionic fiber Postganglionic fiber Note: slide was only found in boys slides
- 8. Sympathetic Division: 1)Preganglionic neurons: located in the lateral gray horn of T1-L2 segments of spinal cord (ThoracoLumbar outflow) Important Note: Sympathetic neurons only found in spinal cord Note: as their preganglionic neurons are short, their ganglia (POSTGANGLIONIC NEURONS) are located near to the CNS (spinal cord). Note: Outflow means the passage of impulses outwardly from the central nervous system. lateral horn Preganglionic neurons
- 9. Sympathetic Division 2)Ganglia (postganglionic neurons) ( Located nearer the central nervous system) depending on their location with respect to the vertebral column they are divided into : 1- Prevertebral ganglia (pre means in front of) 2- Paravertebral ganglia (para means next to) Prevertebral ganglia coeliac & (superior & inferior) mesenteric ganglia (In front of the vertebrae on the abdominal aorta, named after the coeliac and mesenteric arteries where they locate) Postganglionic fibers of Prevertebral ganglia supply: 1) abdominal 2) pelvic viscera Ganglia postganglionic neurons
- 10. Sympathetic Division Paravertebral ganglia Sympathetic chain ganglia (Two interconnected chains, one on each side of vertebral column) Number of ganglia: 3 in the cervical part of the chain 11 to 12 in thoracic part 4 in lumbar & sacral parts each. the chains end into a common “ganglion impar” in front of coccyx. Postganglionic fibers of Paravertebral ganglia supply: 1) structures in head & thorax 2) blood vessels 3) sweat glands 2)Ganglia (postganglionic neurons) Ganglion impar Ganglia postganglionic neurons
- 11. 3) Fibers: Sympathetic Division Within the sympathetic chain, these fibers may: 1- ascend : to move upward. 2- descend : to move downward. 3- remain at the same level to synapse with neurons (postganglionic) of paravertebral ganglia located in sympathetic chain. 4- leave the sympathetic chain (without synapse) to reach coeliac & mesenteric ganglia (around branches of abdominal aorta) to synapse with their neurons (postganglionic). Ascend Descend Leave without synapse Remain branches of abdominal aorta Preganglionic fibers surrounded by Myelin sheath Preganglionic fibers (axon) Run in the ventral roots of the spinal nerve. Travel through the spinal nerve, and then join the sympathetic chain via the White Rami Communicantes (WRC). Note: White ramus Preganglionic fibers (before rely)
- 12. Postganglionic fibers 1- From the sympathetic chain ganglia enter again into the spinal nerve, to supply structure in head & thorax + blood vessels & sweat glands. Enter into the spinal nerve through Grey Rami Communicantes (GRC). note: Grey ramus Postganglionic fibers (after rely). 2- From the cells of (Coeliac, superior & inferior mesenteric) ganglia supply abdominal & pelvic viscera. 3) Fibers: Sympathetic Division Postganglionic fibers
- 13. Parasympathetic Nervous System Preganglionic neuron 1- Cranial: cells in brain stem: nuclei of 3rd, 7th 9th & 10th 2- Sacral: cells in S2 – S4 segments of spinal cord Preganglionic fiber(axon):long axon Postganglionic neuron : located in : 1- Cranial: cells of ciliary, pterygopalatine, submandibular, otic & peripheral ganglia 2- Sacral: cells of peripheral ganglia Postganglionic fiber (axon): short axon Note: slide was only found in boys slides
- 14. Parasympathetic division Cranial outflow Sacral outflow Preganglionic neuron Nuclei of the 3rd, 7th, 9th & 10th cranial nerves, in the brain stem (Cranial outflow) The lateral gray horn of S2-S4 segments of spinal cord (Sacral outflow) Preganglionic fiber (axon) Preganglionic axon leave the brain stem Carried by: 3rd, 7th, 9th & 10th cranial nerve Terminate in: Preganglionic axons leave the spinal cord carried by: pelvic splanchnic nerves (girls slide) leave the spinal cord, join corresponding sacral spinal nerves to reach peripheral ganglia in pelvis where they synapse (boys slide) Terminate in: Postganglionic neuron ciliary pterygopalatine, submandibular, otic & peripheral ganglia peripheral ganglia in pelvis Postganglionic fiber(axon) Postganglionic axons Innervate (supply) organs of the: head, neck, thorax, and abdomen Postganglionic axon Innervate (supply) organs of the: pelvis and lower abdomen helpful video https://youtu.be/PiM_pLLrVto
- 15. Parasympathetic division From boys Doctors 3rd→ciliary ganglion → eye 7th→pterygopalatine ganglion→ lacrimal gland (اﻟﺪﻣﻌﯿﺔ اﻟﻐﺪة ) and mucous membrane (nose and palate) 7th→submandibular ganglia→ Submandibular and sublingual glands اﻟﻠﺴﺎن ﺗﺤﺖ اﻟﺘﻲ اﻟﻐﺪد 9th→otic ganglion→ mucous membrane (mouth) and parotid gland (اﻟﻠﻌﺎب ()ﻹﻧﺘﺎج اﻟﻨﻜﻔﯿﺔ اﻟﻐﺪة ) You have to memorise: 1- Nerves number 2- Name of ganglia 3- Affecting organ
- 16. Autonomic Nervous System Structure Sympathetic effect Parasympathetic effect Iris of the eye(pupils) Dilates pupil Constricts pupil Ciliary muscle of the eye Relaxes Contracts Salivary glands Reduces secretion Increases secretion Lacrimal gland Reduces secretion Increases secretion Heart Increases rate and force of contraction Decreases rate and force of contraction Bronchi (اﻟﮭﻮاﺋﯿﺔ )اﻟﺸﻌﺐ Dilates Constricts Gastrointestinal tract Decreases motility Increases motility Sweat glands Increases secretion ———————- Erector pili muscles (attached to hair follicles) Contracts ——————— Note: Don’t memorize the functions! just know that the Sympathetic and Parasympathetic have a counter effect. Note: the Sweat Gland & Erector pili muscles are only under the sympathetic effect.
- 17. MCQs Question 1: The cell bodies of Preganglionic neuron (Autonomic Nervous System) are located in: A. Autonomic Ganglia B. Brain and Spinal Cord C. Blood Vessels D. Lower Abdomen Question 2: The Parasympathetic division is activated during: A. Exercise B. Fear C. Conserving energy D. Excitement Question 4: Autonomic nervous system is regulated by: A. Hypothalamus B. Pineal gland C. Diencephalon D. Thymus gland Question 3: which of the following is not a sympathetic effect: A. Increase secretion of sweat glands B. Increase secretion of salivary glands C. Relaxes of the ciliary muscle of the eye D. Contracts of the erector pili muscles Answers: 1.B - 2.C - 3.B - 4.A-5.D-6.B- 7.C-8.B Question 5: Preganglionic fibers from cranial outflow are carried by: A. 3rd,5th,11th,8th cranial nerves B. 2nd,4th,7th,9th cranial nerves C. 3rd,5th,8th,10th cranial nerves D. 3rd,7th,9th,10th cranial nerves Question 6: Sympathetic Preganglionic fibers join the sympathetic chain (Autonomic Ganglia) via: A. Ventral rami B. White communicants rami C. Dorsal rami D. Grey communicants rami Question 7: preganglionic fibers of the Sacral outflow are carried by: A. Ciliary ganglion B. Submandibular ganglion C. Pelvic splanchnic nerves D. Peripheral ganglion Question 8: which of the following is a Parasympathetic effect: A. Decreased secretion of lacrimal gland B. Constriction of the ciliary muscle of the eye C. Dilated iris of the eye D. Dilated bronchi
- 18. ● Abdulrahman Shadid ● Ateen Almutairi Contact us: Twitter : @Anatomy438 Boys team: ● Khalid AL-Dossari ● Naif Al-Dossari ● Faisal Alqifari ● Salman Alagla ● Ziyad Al-jofan ● Suhail Basuhail ● Ali Aldawood ● Khalid Nagshabandi Girls team : ● Ajeed AlRashoud ● Taif Alotaibi ● Noura Alturki ● Amirah Al-zahrani ● Alhanouf Al-haluli ● Sara Al-Abdulkarim ● Rawan Alzayed ● Reema Almasoud ● Renad Alhaqbani ● Nouf Alhumaidhi ● Fay AlBuqami ● Jude Alkhalifah ● Nouf Alhussaini Team members Team leaders Good luck to you all A special thanks to the 436 anatomy team, who inspired our work.