Autonomic Nervous System Final Exam 2024 PDF

٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Autonomic nervous system The autonomic nervous system is apart of the nervous system concerned which regulation and control of all involuntary processes in the body. This system helps to control arterial pressure, gastrointestinal motility...

٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Autonomic nervous system The autonomic nervous system is apart of the nervous system concerned which regulation and control of all involuntary processes in the body. This system helps to control arterial pressure, gastrointestinal motility, secretion , urinary bladder emptying , sweating body temperature and many other body activates, some of which are controlled almost completely and some only partially by the autonomic nervous system ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Organization of the nervous system Nervous system Central Peripheral NS NS Autonomic Somatic NS NS Sympathetic Parasympathetic ٢٠٢٤/١١/٥ NS NSMustafa Dr\Mohamed Ahmed  Peripheral nervous system(PNS): is divided into somatic nervous system and Autonomic nervous system Somatic Nervous System: Called voluntary nervous system Control the activity of the voluntary skeletal muscles. Autonomic Nervous System: Called involuntary nervous system Controls the involuntary body activities i.e control visceral activities (Heart, gastrointestinal tract, blood vessels……..) ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  General organization of the Autonomic nervous system The autonomic nervous system is activated mainly by centers located in spinal cord, brain stem, hypothalamus and some parts of the cerebral cortex especially the limbic cortex. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Somatic pathway AHC ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  LHC ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Cross section in the spinal cord ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Somatic NS Autonomic NS Function Controls the voluntary body Controls the involuntary (visceral) activities (skeletal ms.contraction). activities. It is operator system It is regulator system Origin Anterior horn cells (AHC) of spinal Lateral horn cells (LHC) of spinal cord. cord. Number of neuron 1 efferent neuron system and one type 2 efferent neuron system (pre and post ganglionic) Presence of Ganglia Absent 2 type (sympathetic and parasympathetic) Present Response Always excitatory It may be either excitatory or inhibitory neurotransmitter Acetyl choline Acetyl choline or Norepinephrine ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Classification of the autonomic NS Autonomic nervous system Parasympathetic Sympathetic NS Ns ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Sympathetic nervous system Arise from thoracic and lumbar segments of the spinal cord T1 – L3.so it is called Thoracolumbar outflow Most sympathetic preganglionic fibres synapse within ganglia that lie in a sympathetic chain located on either side of the spinal cord. It has short preganglionic & long postganglionic fibres. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa Origin of sympathetic NS (thoracolumbar outflow) 1) LHC of all thoracic segments. 2) LHC of upper 3 or 4 lumbar segments ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Parasympathetic nervous system Arise from the cranial and sacral areas of the CNS. Some cranial nerve 3,7,9,10 and from S2-S4 sacral segments) so it is called Craniosacral outflow. The preganglionic end on short postganlionic neurone located on or near the visceral structures. It has a long preganglionic & short postganglionic fibres. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa Origin of parasympathetic NS Craniosacral outflow 1)Cranial nerves III , VII , IX & X 2)LHC of S2 , 3 & 4. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Origin of parasympathetic NS (Craniosacral outflow) ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa Sympathetic NS Sympathetic division of the ANS is called the fight and flight division. It prepare the body to deal with stress. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa Parasympathetic NS Parasympathetic NS is called the rest and sleep division of the ANS. It allows the body to recover from stress ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa Autonomic ganglia It is a collection of neurons outside the CNS. It is the site of synapse between the preganglionic and the postganglionic neurons. Function: Relay station for preganglionic nerve and origin for postganglionic nerve It act as a distributing center to allow the localized autonomic discharge to be distributed to almost all visceral and involuntary structure. Site of the action of drugs used modify autonomic function. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa N.B the main ganglia for preganglionic sympathetic fibers are lateral ganglia that allow the distribution of preganglionic neuron into a large number of postganglionic fibers and so sympathetic called Generalized system. the main ganglia for preganglionic parasympathetic fibers are terminal ganglia that only allow the distribution of preganglionic neuron into a few number of postganglionic fibers and so parasympathetic called Localized system. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa Types of autonomic ganglia 1- Lateral ganglia or Paravertebral or sympathetic chain *present beside and lateral to the vertebral column. *It was pair of ganglia for each spinal segment but with some exceptions ( 3 cervical, 12 thoracic , 4 lumbar and 4 sacral). *Paravertebral ganglia are sites of relay of preganglionic sympathetic fibers only 2- collateral ganglia: *present in the abdomen, near to the big branches of the aorta *It is the site of relay of preganglionic sympathetic and parasympathetic but mainly sympathetic ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa Types of autonomic ganglia 3-Terminal ganglia: *nearor on the wall of effector organ it is the site of relay of preganglionic parasympathetic fibers only 4-Adrenal ganglia: *it is modified as sympathetic ganglia *It receives preganglionic sympathetic cholinergic fibers. *Secrete catecholamines ( noradrenaline and adrenaline ) in blood in response to sympathetic stimulation to augment and prolong the sympathetic effect on body organ ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Terminal ganglia ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Comparison between the two branches of the autonomic NS Sympathetic NS is characterized by: *The preganglionic fibers synapse either in the lateral or the collateral ganglia. *Short preganglionic fibers. *The postganglionic effects are mediated through norepinepherine. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Parasympathetic NS is characterized by: *The preganglionic fibers synapse in the terminal ga *Long preganglionic fibers. *The postganglionic effects are mediated through chloin ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Adrenal medulla *It is supplied by preganglionic fibers. ( So it is considered as modified sympathetic ganglia). *Its stimulation causes release of catecholamine to blood ( 80% of its secretion is adrenaline and 20% noradrenaline). *It augments and potentiates the effects of sympathetic stimulation. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Origin of sympathetic NS (thoracolumbar outflow) Origin of parasympathetic NS (Craniosacral outflow) ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Functions of the sympathetic NS sympathetic NS is characterized by: It discharges during emergency and stress (fear , fight and flight reaction). It acts as one unit (generalized action). It has catabolic action. Delays evacuation of visceral content. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Sympathetic NS is divided into Cervical division head and neck. Cardiopulmonary division thoracic viscera (heart & lung). Splanchnic division abdomen and Pelvic ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa Cervical division: origin: from lateral horn cell of upper 2 thoracic segmentate of spinal cord effects : 1) Eye 2) Salivary gland 3)Skin. 1) Eye : *pupillodilataion muscle ---------- (Mydriasis). *contraction of Muller’s Muscle ------------protrusion of eyeball (Exophtalmos) * relaxation of ciliary muscles------- for Far vision. 2) Salivary gland: * small in volume ,secretion of viscous saliva rich in enzymes *contraction of myoepithelial cells that squeeze the gland. 3) Skin: * Vaso-constriction of all bl.vs of head and neck *secretion of sweat * Erection of hair by contraction of erector pillae muscles. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa Horner’s Syndrome: AN injury or cutting to the cervical sympathetic that supply to head and neck or damage of the superior cervical sympathetic ganglion on one side of face and leads to: Mitosis: constriction of pupil ( opposite of mydriasis) Ptosis: drooping of upper eyelid Endophthalmos: inward displacement of the eye Anhydsisro: dryness of face due to absence of sweat secretion Redness or flushing of the face: due to persistent ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa vasodilatation. 2) Cardiopulmonary division: supplying the thoracic viscera: origin: from lateral horn of upper 4 thoracic segments of spinal cord. Effect: Heart and Lung. 1) Heart: *increase all cardiac properties of cardiac muscle. ---- cardiac acceleration (+ve chronotropic)related to time, increase contractility ( +ve inotropic) related to contraction., and increase conductivity and excitability. *Vasodilation of coronary vessels *increase COP 2) Lung: * Bronchodilatation, by relaxation of bronchial wall smooth muscle. *Vasoconstriction of pulmonary bl.vs ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa 3) Splanchnic division: Origin : lateral horn of T5-T12 thoracis segments of spinal cord. Relay : *preganglionic fibers originating from T5 – T9 leave sympathetic chain without relay and form the greater splanchnic nerve. *Preganglionic fibers originating from T10-T12 leave the sympathetic chain also without relay and form small splanchnic nerve. Effect : 1) Relaxation of wall of stomach and intestine &contraction of sphincters leading retention of food. 2) Decrease the gastric motility. 3) Inhibition of intestinal secretion. 4)Stimulate glycogenolysis ( glycogen breakdown to glucose) 5)stimulate lipolysis ( lipid breakdown to fatty acid in liver) ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa 6)Relaxation of gall bladder and contraction of sphincter. 7)Stimulate the adrenal medulla to secrete catecholamlnes. 8)Vasoconstriction of visceral bl.vs 9) decrease insulin secretion 10)Contraction of smooth muscle in splenic capsule to squeeze the stored blood ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa Sympathetic supply to the pelvis: Origin: lateral horn of L1-L3 lumber segments of the spinal cord. Effect: 1)urinary bladder: inhibition of the wall of bladder and contraction of the internal urethral sphincter leading to retention of urine (decrease micturition) 2) rectum: inhibition of the wall of rectum and contraction of the internal anal sphincter leading to retention of feces (decrease defecation) 3)genital organ *in male leading to ejaculation. *In female variable effect on plain muscle of uterus ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa FIGHT & FLIGHT REACTIONS 1-Acceleration of the heart. 2-VC in inactive regions 3-Dilatation of bronchi 4-Contraction of spleen 5-Sweat secretion 6-Glycogenolysis 7-Adrenaline &noradrenaline are secreted ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Functions of the parasympathetic NS Parasympathetic NS is characterized by: It discharges during rest and sleep. Its action is localized. It has anabolic action (conserve body stores ). It increases gastrointestinal secretion & ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa motility ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa Parasympathetic supply is formed of cranial part and sacral part: A) The cranial outflow: rd 1) The oculomotor nerve (3 cranial nerve) Effect: *Contraction of constrictor pupillae muscle produce miosis. *Contraction of ciliary muscle--------increase the convexity of lens to allow increase lens power for near vision ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  th 2) The Facial nerve (7 cranial) Effect: *secretion of watery saliva , poor in enzyme and large volume *secretion of tears. *Vasodilatation of bl.vs of salivary gland. th 3) The Glossopharyngeal nerve (9 cranial) Effect: *secretion of parotid gland *Vasodilatation of bl.vs. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  th 4) The Vagus nerve (10 cranial) origin: motor nucleus of vagus in medulla oblongata. Relay: Terminal ganglion. Effect: 1) in heart : *inhibits all cardiac properties. *Vascoconctriction of coronary bl.vs. *Decrease Cardiac output 2) In lung: * bronchoconstriction * VD of Pulmonary bl.vs *secretion of mucus. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa 3) In GIT: *contraction the wall of esophagues, stomach , small intestine and proximal part of large intestine * inhibition of sphincters ------- help evacuation of food *increase secretory to stomach, liver and pancreas to help digestion. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa B) The Sacral outflow: origin: lateral horn S2-S4 sacral segments of spinal cord. Relay: terminal ganglion Effect: 1-Urinary bladder: *motor (stimulatory ) to the wall and inhibitory to internal urethral sphincter ----- help micturition. 2-Rectum and colon: * motor (stimulatory ) to the wall and inhibitory their sphincter ----- help defecation. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  3- Genitalia: *Erectile tissue and external genitalia. *stimulation of secretion of prostate and seminal vesicle in male. *Vasodilatation of bl.vs of penis and clitoris in female causing erection. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Dual innervation Almost all visceral organs are supplied by both sympathetic and parasympathetic divisions of the autonomic NS. This double innervation is stimulated equally at the same time. Which division predominate at any given time is determined by the body demands at that time. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Structures supplied only by sympathetic nervous system: Skin (sweat glands, hair & blood vessels). Dilator pupillae muscle. Blood vessels of the skeletal muscles. Ventricles of the heart. Adrenal medulla. Spleen. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa Uterus.  Structures supplied only by Parasympathetic nervous system: Constrictor pupillae muscle. Gastric glands. Esophageal muscles. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa NEUROTRANSMITTERS Sympathetic &Parasympathetic preganglionic fibres release ACETYLCHOLINE. Parasympathetic postganglionic release ACETYLCHOLINE. Sympathetic postganglionic ( most )release NOREPINEPHRINE. EXCEPT Postganglionic fibres which innervate : -sweat glands & BVs of skeletal muscles. N.B *all autonomic preganglionic fibers are called Cholinergic *The most postganglionic sympathetic are called Adrenergic ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  CHEMICAL TRANSMISSION AT AUTONOMIC JUNCTIONS Transmission at the synaptic junction between : --pre & postganglionic neurons - postganglionic neurones & effector organs. Are chemically mediated by neurotransmitters. The principal transmitter agents involved are: Acetyl choline &Norepinephrine. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa Neurotransmitters exert their actions by combination with specific receptor  Chemical transmission in autonomic Ns Parasympathetic NS Sympathetic NS Somatic NS ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Chemical transmission in Parasympathetic NS The postganglionic effect of the parasympathetic NS is mediated mainly by acetyl choline, so it is called the cholinergic system. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Sites of the cholinergic fibers ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  SYNTHESIS OF ACETYL CHOLINE 1 choline +acetyl COA-------Acetyl choline +COA CAT 2 Storage of Ach in synaptic vesicles until needed 3 Release of Ach : when impulse arrives at nerve endings , open ca++ channels causes release of Ach. 4 Binding of Ach to postsynaptic cholinergic receptors on the target. 5 Degradation of acetylcholine by cholinesterase enzyme to choline + acetate ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa 6 Recycling of choline into the neurone.  Fate (destruction) of acetyl choline: *Ach is broken down by choline esterase enzyme. Acetic acid Choline esterase enzyme Acetyl choline Choline base *Destruction of the acetyl choline occurs at faster rate compared to the destruction of noradrenaline. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Autonomic receptors They are chemical structures found mainly on the cell membrane of the effector organs. They are affected by the combination with chemicals or drugs. They are classified into 2 main groups: ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Cholinergic receptors It is the division of the autonomic receptors which can be stimulated by acetyl choline. It is classified into 2 types according to its sensitivity to drugs. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa Site Effector organs supplied by: -All autonomic ganglia. -All parasympathetic -Adrenal medulla. postganglionic fibers. -Motor end plate. -Sympathetic cholinergic fibers (sweat glands & bv. Of skeletal ms.) Stimulated by: -Acetyl choline. -Acetyl choline. -Muscarine. -Nicotine small dose. Blocked by: Atropine Nicotine large dose. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  RESPONSE OF NICOTINIC RECEPTORS TO ACH Are all exitatory ,fast & lasting very short time.foe eg: Stimulation of autonomic ganglia ganglion transmission. Stimulation of neuromuscular junction skeletal muscle contraction. Stimulation of adrenal medulla secretion of epinephrine &norepinephrine. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Chemical transmission in sympathetic NS The postganglionic effect of the sympathetic NS is mediated mainly by noradrenaline, so it is called the adrenergic system. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Sites of the adrenergic fibers Adrenergic fibers All postganglionic sympathetic fibers except (sweat glands & bv. Of skeletal muscle) ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa  Adrenergic receptors It is the division of the autonomic receptors which can be stimulated by catecholamine (epinephrine & norepinephrine). It is classified into 2 types according to its sensitivity to drugs. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa Action They are mostly excitatory. They are mostly inhibitory. i.e. on stimulation, they cause the i.e. on stimulation, they cause the smooth ms. To contract. smooth ms. To relax. Site -Blood vessels (vasoconstriction). -Blood vessels (vasodilation). -Splenic capsule (contraction). -Bronchi (bronchodilation). -GIT sphincter ( contraction). -GIT wall (relaxation). Exception: cardiac ms. ( increase its contraction force). Stimulated Mainly by noradrenaline. Mainly by adrenaline. by: Blocked by: Phentolamine Propranolol. ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa ٢٠٢٤/١١/٥ Dr\Mohamed Ahmed Mustafa