2. The autonomic nervous system The nervous system is divided anatomically into: central & peripheral NS The nervous system is divided physiologically into: somatic (deals with voluntary & conscious aspects as skeletal movements &somatic sensation) autonomic(deals with involuntary mechanisms as regulation of heart, blood vessels,, digestive function) Both systems are inter- related and their functions are complementary

3. Somatic and Autonomic Nervous System

4. The division of the autonomic nervous system ANS does not arise from all segments of the nervous system, but from certain regions only. ANS is divided into: Sympathetic NS: arise from lateral horn cells of thoracic segments and the upper two lumbar segments (thoraco-lumbar outflow). Parasympathetic NS: (cranio-sacral outflow), cranial nerves III,VII, IX, to the head & neck structures and X (Vagus) to thorax and abdomen sacral outflow from lateral horn cells of 2 nd, 3 rd &4 th sacral segments to the pelvis

6. Organization of the autonomic nerves It is two neurons system: Preganglionic & postganglionic Preganglionic sympathetic arises from lateral horn cells of all thoracic & upper lumbar & relay in paravertebral sympathetic chain

7. Autonomic ganglia Def: it is collection of nerve cells (postganglionic neurons) outside CNS, They are stations where impulses from preganglionic relay to the postganglionic neurons Types: 1- lateral ganglia: 2 sympathetic chains on either sides of the vertebral column 2- collateral ganglia: in the abdomen, on large arteries, for sympathetic or parasympathetic 3- terminal ganglia: parasympathetic, at the organs Functions: Relay stations Distributing center Release chemical transmitters Regeneration of postganglionic fibers

9. Sympathetic pathways

10. Autonomic Nervous System Sympathetic nerves (fight or flight) Sympathetic chain (ganglia) next to spinal cord Parasympathetic nerves (rest and digest) Ganglia next to organs

11. Functions of sympathetic NS On head & neck: Origin: Preganglionic fibers originate from upper thoracic segments and relay in the superior cervical sympathetic ganglion. Postganglionic fibers pass with the carotid arteries Functions: 1- the eye: Dilatation of the pupil (mydriasis) Relaxation of ciliary muscle (decrease the lens power for far vision) Motor to tarsal muscles: widens the palpebral fissure Motor to Muller`s muscle: exophthalmos in animals Vasoconstriction of the blood vessels of the eye Lacrimal glands: decrease tear secretion & VC 2- skin: Sweat glands :Copious secretions (cholinergic fibers) BV, vasoconstriction Erection of hair 3- salivary glands: Trophic secretion (small in amount, viscid & concentrated) 4- cerebral vessels: Mild vasoconstriction., but the cerebral blood flow increase due to increase blood pressure

12. On thorax: (cardiopulmonary) Origin: upper 4 thoracic segments, relay in the cervical and the upper 4 thoracic ganglia 1- heart: Increase all cardiac muscle properties, cardiac metabolism & O2 consumption (contractility, rhythmicity, conductivity, excitability) (Increase strength of contraction, heart rate) 2-dilatation of the coronary 3- bronchial muscle: Broncho-dilatation & inhibit bronchial secretion 4- pulmonary BVs: vasoconstriction

13. On the abdomen (splanchnic ): Origin: lower 8 thoracic & upper 2 lumbar, forming greater & lesser splanchnic nerves relay in the celiac & superior mesenteric ganglia. The lumbar fibers of both sides unite to form presacral nerve, relay in the inferior mesenteric ganglion. 1-GITglands: decrease secretion 2-Wall motility: decrease 3-Sphincters: contraction 4-Splanchnic vessels mainly vasoconstriction 5-Spleen: contraction of the capsule to add 50ml stored blood into the circulation 6-Liver: glycogenolysis…. Increase blood glucose level 7-Pancreas: inhibit insulin secretion 8-Kidney: decrease renal blood flow, decrease urine volume, increase rennin secretion 9-Adrenal medulla: secretion of adrenaline and noradrenaline 10-Urinary bladder: inhibition of the wall &contraction of internal urinary sphincter, retention of urine & prevent semen flow to bladder 11-Ureters, uterus & fallopian tubes: mainly relaxation, may be stimulator to the uterus in late pregnancy 12-rectum; inhibitory to the wall & motor to the internal anal sphincter (retention of feces 13-Smooth muscles of epididymis, vas deferens, seminal vesicles and prostate: motor.. Ejaculation of semen

14. Somatic division: to the upper & lower limbs: Upper limb: origin: from 4 th to 8 th thoracic segments, relay in lower cervical & upper 4 thoracic ganglia, posttganglionic fibers join the brachial plexus Lower limbs: origin: 10 th thoracic to the 2 nd lumbar segment, relay in lumbar & sacral ganglia Function: Blood vessels of skeletal muscles: vasodilatation Skeletal muscles: delay fatigue (Orbilli phenomenon) Skin: Sweat gland: secretion of sweat Cutaneous blood vessels: VC Erector pilae muscle: piloerection, hair erection

15. General function of the sympathetic nervous system (alarm respnse or stress response) In emergency conditions: in fight, flight, muscular exercise, emotions, pain, cold, generalized sympathetic stimulation occurs: a- acceleration of the heart b- vasoconstriction in inactive regions: skin & splanchnic c- dilatation of the bronchi d- contraction of spleen e- excess sweat secretion f- delay muscle fatigue g- glycogenolysis h- stimulate adrenal medulla to secrete adrenaline & noradrenaline to intensify all reactions i- adrenaline stimulation of the brain to increase alertness and shorten response time

18. Horner`s Syndrome It is unilateral lesion affecting the sympathetic supply to the head & neck due to lesion in the superior cervical sympathetic ganglion. Manifestations: 1- Ptosis: drop of upper eye lid 2- Miosis: pupillo-constriction 3- Anhydrosis: dryness of skin due to absence of sweat 4- Enophthalmos: inward sinking of the eye ball 5- Flushing (redness) and warming of the affected side of the face due to vasodilatation of the skin vessels

19. Parasympathetic pathways

20. Functions of parasympathetic NS Occulomotor nerve (III cranial nerve): arises in midbrain, relay in ciliary ganglion, postganglionic as short ciliary nerves functions: in the eye: 1- constriction of the pupil (miosis) 2- contraction of ciliary muscle increase the power of lens for near vision

21. Facial nerve (VII cranial nerve): Origin: pons & upper medulla gives Functions: chorda tympani branch, relay in submaxillary ganglion to submaxillary & sublingual salivary glands: increase secretion rich in enzymes with lingual nerve to tongue: vasodilatation some fibers relay in sphenopalatine ganglion, post ganglionic fibers supply nasopharynx and lacrimal glands: increase secretion and vasodilatation Glossopharyngeal nerve (IX cranial nerve) Origin: medulla Relay in otic ganglion Postganglionic fibers supply parotid salivary gland: secretory & vasodilataion

22. The vagus nerve (X cranial nerve): Origin: medulla Relay in the terminal ganglia 75% of parasympathetic fibres are in vagus nerve Functions: 1- heart: Decrease heart rate (bradycardia) Slow conductivty Inhibit contractility of the atria only No effect on strength of contraction of ventricle (vagus does not supply the ventricles) Decrease cardiac metabolism 2-coronary vasoconstriction 3- bronchial muscle: Broncho constriction & increase mucus secretion. High vagal tone →bronchial asthma 4- Gastrointestinal tracts: Wall motility: increase Sphincters: relaxation Secretions: increase stomach, exocrine pancreas & liver secretion 5-Gall bladder: weak contraction of the wall 6-Pullmonary & gastric blood vessels weak vasodilatation

23. 5- the sacral autonomic outflow (pelvic visceral nerve): Origin: lateral horn cells of sacral segments2,3 &4 Relay in terminal ganglia Functions: 1-Urinary bladder: motor to the wall, inhibitory to the internal urinary sphincter → micturition 2-Distal half of the colon: motor to the wall & inhibitory to the internal anal sphincter → defecation 3-Erectile tissue of the external genitalia → erection 4-Seminal vessels and prostate → stimulate secretion 5-Pelvic blood vessels → vasodilatation

24. General functions of parasympathetic system Parasympathetic system is anabolic and energy preserving: at rest, digest, reading 1- inhibits cardiac properties 2-increases activity of GIT

26. Neurotransmitters and receptors in the autonomic nervous system

27. Autonomic pathways

28. Sympathetic and Parasympathetic The effects of sympathetic and parasympathetic stimulation are produced by the release of chemical substances called chemical transmitters

29. Chemical Transmitters  Types: acetyl choline &noradrenaline  Nerves secrete Ach are called cholinergic nerves  Nerves secrete noradrenaline are called adrenergic nerves  Receptors activated by Ach are called cholinergic receptors with subtypes nicotinic & muscarinic  Receptors activated by noradrenaline are called adrenergic receptors with subtypes α & β

30. Acetyl choline Sites of release of acetyl choline (cholinergic fibers) 1-Central cholinergic fibers: arises directly from the CNS: All preganglionic sympathetic fibers, including the preganglionic fiibers to the adrenal medulla. All preganglionic parasympathetic fibers In all the ganglia, the transmitters is ACETYL CHOLINE. All the somatic motor fibers to skeletal muscles 2-Peripheral cholinergic fibers (postganglionic) All postganglionic parasympathetic postganglionic sympathetic VD fibers to skeletal muscle BV postganglionic sympathetic secretory to sweat gland

31. Neurotransmitters ACh Sweat glands Striated muscle ACh SOMATIC NERVOUS SYSTEM Heart Sm. mus. Glands ACh Parasympathetic ACh E, NE Ad. M.  Heart Sm. mus. Glands ACh NE AUTONOMIC NERVOUS SYSTEM Sympathetic

32. Actions of acetyl choline 1- activation of the autonomic ganglia cells & the motor end plate of skeletal muscle. These actions are also produced by small doses of nicotine, so they are called nicotinic – like actions of acetyl choline & the receptors are called nicotinic receptors 2- activation of parasympathetic action on the eye and viscera & sympathetic actions to sweat glands and blood vessels of skeletal muscle & some parts in the brain. These actions are also produced of muscarine, so they are called muscarine -like actions of acetyl choline & the receptors are called muscarinic receptors

33. Myasthenia Gravis (MG) a disease of neuromuscular junction Characterized by weakness of skeletal muscle, easy fatigability may affect the respiratory muscles and cause death More in female Affects young adults (18-25) It is suspected to be a cellular type of autoimmunity (the patient T- lymphocytes attack the neuromuscular junction) leading to; 1- lack of acetyl choline release 2- widening of synaptic cleft at the motor end plate 3- destruction of the cell membrane over the motor end plate, decreasing the receptor area for acetyl choline

34. Catecholamines Noradrenaline : Site of release: most postganglionic sympathetic nerves & Adrenal medulla in addition to adrenaline Adrenergic receptors: They are either: 1- alpha adrenergic,(alpha1, alpha2) 2- beta adrenergic, (beta1, beta2) Different receptors produce different actions The effect of catecholamine on organs depends on the type of receptors in this organ