The autonomic system ppt presentation.pptx

Autonomic nervous system

1. Principles of autonomic nervous system Presenter fahad Hussein Yusuf Supervisor Dr mugisa B.Didace

2. Objectives Defination of autonomic nervous system Organisation of autonomic nervous system Symapathetic and Parasympathetic out flow Function of parasympatetic , sympatetic and enteric nervous system Callinical correlations pf Autonomic nervous

3. Definition The ANS or vegetative nervous system is a system responsible for controlling functions that do not require conscious thought. Controls unconscious involuntary, and visceral body functions Innervates smooth Muscles,cardiac Muscles and Glands of the body. Trajectory: CNS → ganglion → target tissue

4. Organisation of autonomic nervous systems

5. Sympathetic neurons Cell bodies of preganglionic neurons are located in the spinal cord Emerge from the thoracolumbar regions Located in the intermediolateral columns (lateral horns) Presynaptic fibers exit the spinal cord through the anterior roots and enter the anterior rami of T1‒L2.

6. Course of preganglionic fibers 1- Synapse with a post ganglionic neuron in the ganglion at that level 2- Pass up or down to a different level of the sympathetic trunk before synapsing with a post ganglionic neuron 3- The pre ganglionic fiber may traverse the sympathetic chain ganglia without synapsing and leave as splanchnic nerve to synapse with post ganglionic neuron in pre-vertebral ganglion or adrenal medullae

7. Sympathetic trunk The ganglionated sympathetic trunks lie anterior to the heads of the ribs; the ganglia are arranged segmentally from cervical region up to coccyx bones. Preganglionic sympathetic axons originate from neurones in the lateral grey column of the spinal cord from T1 to L2, and leave the spinal cord with the corresponding ventral roots as white rami communicantes Their targets vary.

8. Con... Some enter the sympathetic trunk, where they either synapse in their segmental ganglion or ascend or descend in the trunk to synapse in cervical or lumbar ganglia. Many of the preganglionic axons which originate in the lower thoracic spinal segments (T5–12) do not synapse locally but enter the abdominal cavity as the thoracic splanchnic nerves and synapse either in prevertebral ganglia, especially the coeliac ganglion, or around the medullary chromaffin cells of the suprarenal gland . Axons destined for the cervical ganglia are derived from preganglionic neurones in T1

9. Paravertebral ganglia  are found on the left and right side of the body parallel to the vertebral column (hence the naming paravertebral)and are linked together in a chain to form the left and right sympathetic trunk or sympathetic chain. Each trunk begins from the base of the skull with the superior cervical ganglion. The trunks unite at the level of coccyx and form the ganglion impar. 

10. Prevertebral ganglia (collateral ganglia, preaortic ganglia) lie anterior to the vertebral column, forming several plexuses around the major branches of the abdominal  aorta, such as celiac ganglia around  celiac trunk Preganglionic fibers leave the spinal cord through the anterior roots and anterior branches of  spinal nerves  as the white rami communicantes which then synapse with either paravertebral or prevertebral ganglia.

11. Distal to the paravertebral ganglia, all nerves become splanchnic nerves. Splanchnic nerves contain  afferent and  efferent  fibers that convey information between the CNS and visceral structures: Cardiopulmonary splanchnic nerves carry postsynaptic fibers that innervate the thoracic viscera. Abdominopelvic splanchnic nerves carry postsynaptic fibers that innervate the abdominal and pelvic viscera

12. Postganglionic sympathetic  neurons then travel to their target tissues where they stimulate sympathetic activity specific to the target organ.NE is released as a neurotransmitter at adrenergic  receptors  in most organs. Adrenergic  receptors  include: Alpha-1 and 2  receptors Beta-1, 2, and 3  receptors

13. Sympathetic functions the SNS  triggers the “fight-or-flight” response in reaction to physiologic stress. Primarily a vascular response Most vessels respond to sympathetic stimulation by  vasoconstriction and redirect  blood flow vital to “fight-or-flight” from: Abdominal visceral organs  Pelvic visceral organs

14. Parasympathetic nervous system Parasympathetic fibers emerge from the craniosacral regions of the nervous system. Cell bodies of the preganglionic neurons are located in the cranial nerve (CN) nuclei (CN III, CN VII, CN IX, and CN X) and in the terminal portion of the spinal cord.

15. Cranial outflow (brainstem) Oculomotor nerve (CN III) – iris, ciliary muscles Facial nerve (CN VII) – lacrimal, nasal, palatine, pharyngeal, sublingual, submandibular glands Glossopharyngeal nerve (CN IX) – parotid gland Vagus nerve (CN X) – heart, larynx, trachea, bronchi, lungs, liver, gallbladder, stomach, pancreas, kidney, small intestine, proximal large intestine Sacral outflow (S2-S4) Pelvic splanchnic nerves – descending colon, sigmoid colon, rectum, bladder, penis or clitoris

16. Preganglionic fibers from III, VII, and IX CN end by synapsing with post ganglionic neurons in four large parasympathetic ganglia The pre ganglionic fibers of the vagus nerve go beyond the head region to synapse with post ganglionic cell bodies in ganglia adjacent or in the walls of viscera (heart, lungs, stomach and intestine)

17. The preganglionic fibers from the sacral part leave the SC through ventral routes of the 3rd and 4th sacral nerves From the spinal nerves the separate as pelvic splanchnic nerve Post ganglionic parasympathetic ganglion are located on the surface or in the substance of visceral organ being supplied (lower large intestine, sphincter muscles of the urinary bladder and urethra etc.

18. Ciliary ganglion Oculomotor Orbit ciliary muscles and constricter pupili Pterygopalatine ganglion Facial nerves Pterygopalatine fossa lacrimal glands, glands of nose, nasopharynx, paranasal sinuses Submandibular ganglion Facial nerve Submandibular region submandibular and sublingual salivary glands Otic ganglion glasopharyngal Infratemporal fossa parotid salivary glands

19. Enteric nervous system Intramural  nervous system Located in the wall of the GI tract (plexus entericus) Consists of 2 ganglion-rich plexuses:Submucous plexus ( Meissner plexus) found in the submucosa → regulates fluid and electrolyte movement across the  intestinal mucosa Myenteric plexus  ( Auerbach plexus) found in the muscularis propria between the longitudinal and circular layers of the smooth muscle in walls of the GI tract → coordinates smooth muscle contractions involved in  peristalsis

20. Clinical correlations Horner syndrome:  a condition resulting from any pathology that causes damage to the sympathetic nerves of 1 side of the face, affecting the sympathetic output of the superior cervical ganglion.  Horner syndrome  results from a traumatic injury, a disease, or a hereditary  mutation. A commonly examined scenario is where  Horner syndrome can present in a Pancoast lung  tumor  and its metastatic spread can invade the sympathetic chain. Symptoms include unilateral  miosis  and  ptosis, as well as anhidrosis of the affected side of the face.

21. Multiple sclerosis:   a chronic, immune-mediated, progressive inflammatory CNS disease that damages the myelin sheath and nerve cells to varying degrees. As the name of this disease implies, multiple areas of induration (scleroses) are seen in the CNS. Symptoms are varied and include weakness, numbness, tremor and visual disturbances. The disease course is progressively degenerative.

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