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Autonomic Nervous System Organization Sympathetic Parasympathetic Functional May 7, 2017 Anatomy ANS 1 Functional Anatomy ANS control the activity of Smooth muscles of all organs Cardiac muscles Secretions of glands Mediates the neural control of internal environment May 7, 2017 Blood pressure, GIT motility and secretions, urinary output, sweating and temperature control ANS 2 Functional Anatomy Activated by centers located in the Spinal cord Brain stem Hypothalamus Cerebral cortex May 7, 2017 ANS 3 Functional Anatomy Customarily subdivided into Sympathetic Parasympathetic Sympathetic was thought to act In sympathy with emotions Fear, rage Parasympathetic was thought to May 7, 2017 Restrain sympathetic promoting calmness ANS 4 Sympathetic System Cell bodies of the pre-ganglionic nerves Located in the lateral horns of Thoracic and lumbar spinal cord segments Pre-ganglionic fibres leave the spinal cord via the ventral root May 7, 2017 Join the spinal nerve They then leave the spinal nerve via white ramus communicantes Join the sympathetic ganglia where ANS 5 Sympathetic System Either synapse with post-ganglionic nerve Rejoins the spinal nerve via gray ramus communicantes Innervate effector organs Or pass directly to a collateral ganglia to synapse with postganglionic nerve Divergence and convergence May 7, 2017 ANS 6 Dorsal root ganglia Pre-ganglionic Ventral root Spinal nerve Ganglia chain Gray ramus Collateral ganglia May 7, 2017 ANS 7 White ramus Post-ganglionic Effector organs Somatic nervous system ganglia Pre-ganglionic Parasympathetic Post- Preganglionic ganglia Post-ganglionic Sympathetic Adrenal Medulla May 7, 2017 ANS catecholamine 8 Adrenal Medulla Cells of adrenal medulla are derived from nervous tissue Analogous to postganglionic nerves Preganglionic fibres Pass through symp. Chain of ganglia Synapse with adrenal medulla cells Cells secrete adrenalin, Nor adrenalin and dopamine May 7, 2017 ANS 9 Parasympathetic System Cell bodies of the pre-ganglionic neurons found Nuclei of cranial nerves in midbrain and medulla Give origin to cranial parasympathetic outflow From the sacral segment of spinal cord May 7, 2017 Cell bodies of pre-ganglionic nerves give rise to sacral parasympathetic outflow ANS 10 Parasympathetic system Effector organ Pre-ganglionic fibre Nucleus Or Either ganglion Postganglionic fibre The Parasympathetic ganglia is •Either in the viscera (effector organ) •Or close to the viscera (effector organ) May 7, 2017 ANS 11 Parasympathetic Midbrain From Edinger Westphal nucleus Pre-ganglionic nerve join the occulomotor nerve Synapse with post-ganglionic nerve in ciliary ganglia Innervate the ciliary and pupillary muscles of the eye occulomotor Ciliary muscle Pupillary constrictor E W Nucleus May 7, 2017 Ciliary ganglia ANS 12 Parasympathetic Pons From Lacrimal and Salivatory nucleus Preganglionic May 7, 2017 fibres join the facial nerve to The sphenopalatine ganglia Synapse with post-ganglionic fibres Innervate the lacrimal glands Submandibular ganglion Synapse with post-ganglionic fibres Innervate submandibular and sublingual glands ANS 13 Sphenopalatine ganglia Pons Lacrimal gland Facial Nerve Submandibular ganglia Submandibular and sublingual glands Medulla IX Parotid gland Otic ganglia Inferior salivatory Nucleus May 7, 2017 ANS 14 Parasympathetic From the inferior salivatory nucleus Pre-ganglionic fibres join IX to Otic ganglia Innervate parotid glands From dorsal motor nucleus of VAGUS Preganglionic fibres join the vagus nerve May 7, 2017 Synapse with post ganglionic nerves in various effector organs in thorax and abdomen ANS 15 vagus Heart Lungs Dorsal motor nucleus of vagus Oesophagus Stomach Small intestines Colon May 7, 2017 ANS Liver, gall bladder, Pancreas, ureters 16 Sacral Parasympathetic Outflow From lateral horns of grey matter Sacral segment 2,3,4 Preganglionic fibres leave to join nerve eregentes to sacral plexus Synapse with post synaptic nerves Innervate effector organs May 7, 2017 Descending colon Rectum Urinary bladder Lower potions of ureters External genitalia ANS 17 ANS Transmission Chemical transmission Acetylcholine (Ach) Nor adrenalin Dopamine GnRH Co-transmitters VIP released with ach ATP and neuropeptide Y released with Nor adrenalin May 7, 2017 ANS 18 Chemical Division of ANS Cholinergic All pre-ganglionic neurons Also included Parasympathetic post-ganglionic neurons Sympathetic neurons which innervate sweat glands Sympathetic neurons which end on blood vessel to skeletal muscles causing vasodilatation Noradrenergic May 7, 2017 Remaining sympathetic postganglionic nerves ANS 19 Chemical Division of ANS Adrenal medulla Essentially sympathetic ganglia Post-ganglionic nerves have lost the axons Secretes into blood Adrenalin Nor adrenalin Dopamine May 7, 2017 ANS 20 ANS Neurotransmitters At the ganglia Acetylcholine Both sympathetic and Parasympathetic release Acetylcholine as the neurotransmiter May 7, 2017 ANS 21 Postganglionic Parasympathetic Release Acetylcholine which can cause both Excitation Inhibition Excitation occur Smooth muscle of stomach, intestines, bladder, bronchi On glands May 7, 2017 ANS 22 Mechanisms of Ach Action Ach bind to receptors Ach increase the concentration of ca++ in ICF Cause depolarization Increase ca++ conductance Ca++ initiate contraction Acetylcholine bind to membrane receptors Activate membrane bound G-protein May 7, 2017 Guanosine triphosphate (GTP) ANS 23 Mechanism of Ach Actions Activation of G-protein Stimulation of Phospholipase C Breakdown of Phosphatidylinositol bisphosphate (PIP2) into DAG & IP3 which then Initiate membrane and intracellular events leading to muscle contraction May 7, 2017 ANS 24 Ach receptor G-Protein Membrane bound Lipase DAG + IP3 PIP2 Opening Ionic channels Diacylglycerol Inositol Triphosphate Protein Kinase Ca++ Ca++ Muscle May 7, 2017 contraction ICF ANS Sarcoplasmic Reticulum 25 Inhibitory effect of acetylcholine Ach K+ On the heart SAN, AVN Ach bind to receptor Activation of ionic channels K+ ion efflux K+ Pr - Pr K+ May 7, 2017 K+ - K+ Hyperpolarization K+ Decrease Pacemaker activity K+ K+ ANS 26 Sympathetic Dopamine Ach Nor-epinephrine (ATP, Neuropeptide Y) β α Nor-adrenalin Has got both Excitatory and Inhibitory effects May 7, 2017 ANS 27 Noradrenalin Binding to β receptors Activates Gs protein Adenylate cyclase ATP cAMP Increase in cAMP Activation May 7, 2017 of protein Kinase A variety of physiological activities ANS 28 Noradrenalin β-receptor Gs-Protein Adenylate Cyclase Opening Ionic channels ATP Active Protein Kinanse cAMP Inactive Protein Kinase Variety of Physiological Functions May 7, 2017 ANS 29 Binding to β receptors On the heart The activated protein Kinase Phosphorylate Ca++ channels Increase of Ca++ entry into the cell Increase in contractility Increase in force of contraction May 7, 2017 ANS 30 Binding to β receptors On bronchial smooth muscles Activated protein Kinase Phosphorylate Ca++ channels on sarcoplasmic reticulum Increase of Ca++ entry into the sarcoplasmic reticulum Decrease in [Ca++ ] in cytoplasm Decrease force of contraction May 7, 2017 ANS 31 Noradrenalin binding to α-Receptors Two types : α1 and α2 Binding to α1 receptors Activation of Gs Protein system Stimulation of Phospholipase C Breakdown of Phosphatidylinostol bisphosphate (PIP2) into DAG & IP3 which then Initiate variety of physiological activities May 7, 2017 ANS 32 Noradrenalin on α2 Activation of Gi Protein Adenylate cyclase is inhibited Decreased concentration of cAMP Inhibition of variety of Physiologic effects May 7, 2017 ANS 33 Actions of Autonomic Nervous System on Organs Dual innervations The eyes, salivary glands, heart, digestive system, pelvic viscera Receive both sympathetic and parasympathetic innervations The two system occasionally act antagonistically However, in most organs one system is dominant Under physiological condition May 7, 2017 Parasympathetic activity predominates ANS 34 Dual innervations Sweat gland , adrenal medulla, piloerectors and majority of blood vessels May 7, 2017 Receive sympathetic innervation only ANS 35 The EYE The Pupil Radial Muscles Circular muscles •Sympathetic •Parasympathetic •Contraction •Contraction •Pupillary dilatation •Pupillary constriction May 7, 2017 ANS 36 Lens Ciliary muscles Suspensory ligaments Lens Parasympathetic Sympathetic Stimulate ciliary muscles Inhibition of the Muscle Contraction Relaxation Ligaments loosen Suspensory ligaments tighten Lens focuses for Near Vision Lens focuses for far vision May 7, 2017 ANS 37 ANS Effects On Glands Nasal, lacrimal, salivary, GIT glands Strongly stimulated by parasympathetic Leads to increased amounts of secretions by the glands Sympathetic Little direct effect Causes vasoconstriction May 7, 2017 Decreases blood flow Hence decrease in the rate of secretion ANS 38 ANS Effects On Glands Sweat glands Stimulated by sympathetic nerves Which are mostly cholinergic Primarily stimulated by centers in the hypothalamus considered parasympathetic Apocrine glands Sympathetic stimulation Produce May 7, 2017 thick odoriferous secretion ANS 39 ANS Effects GIT Intramural plexuses Myenteric (Auerbachs) Meissners (Submucosal plexus) Parasympathetic nerves end on Myenteric and Meissners plexuses Stimulation causes May 7, 2017 Excitation of intestinal smooth muscles Relaxation of sphincters . Aowing rapid propusion of contents aong the tracts ANS 40 ANS Effects Leads to increased in overall activity Increased peristalsis Decrease in gastric and intestinal emptying time Increase in gastrin and gastric glands secretions May 7, 2017 ANS 41 ANS Effects Sympathetic nerves terminate on Blood vessels Cause vasoconstriction Smooth muscles Increase tone of sphincters Inhibit motility of GIT…net resut is greaty sowed propuision of food thru the tract and sx deacreased secreation as we to the extent of causing constipation May 7, 2017 ANS 42 ANS Effects on the Heart Both sympathetic and parasympathetic Sympathetic Accelerates the pace maker Increases speed of conduction (positive chronotropic) Increases the force of contraction (positive ionotropic) Overall effect May 7, 2017 Increase the effectiveness of the heart ANS 43 ANS Effects on the Heart Parasympathetic Retards the depolarization of pacemaker cells Slows conduction of cardiac impulse (negative chronotropic) Decreases the strength of contraction (negative inotropic) Overall effect Decrease May 7, 2017 the effectiveness of the heart ANS 44