August 14, 2015ANS 1 AUTONOMIC NERVOUS SYSTEM Organization Sympathetic Parasympathetic Functional Anatomy

 ANS control the activity of  Smooth muscles of all organs  Cardiac muscles  Secretions of glands  Mediates the neural control of internal environment  Blood pressure, GIT motility and secretions, urinary output, sweating and temperature control August 14, 2015ANS 2

Functional Anatomy  Activated by centers located in the  Spinal cord  Brain stem  Hypothalamus  Cerebral cortex August 14, 2015ANS 3

Functional Anatomy  Customarily subdivided into  Sympathetic  Parasympathetic  Sympathetic was thought to act  In sympathy with emotions  Fear, rage  Parasympathetic was thought to  Restrain sympathetic promoting calmness August 14, 2015ANS 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  Join the spinal nerve  They then leave the spinal nerve via white ramus communicantes  Join the sympathetic ganglia where August 14, 2015ANS 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 August 14, 2015ANS 6

August 14, 2015ANS 7 Dorsal root ganglia Ventral root Ganglia chain Collateral ganglia White ramus Gray ramus Spinal nerve Pre-ganglionic Post-ganglionic

August 14, 2015ANS 8 Somatic nervous system Effector organs Parasympathetic ganglia Sympathetic ganglia Pre- ganglionic Post-ganglionic Post- Pre-ganglionic Adrenal Medulla catecholamine

Autonomic N.S (involuntary) Somatic N.S (voluntary) 1) Supply smooth muscles, Cardiac and Glands 1) Innervate skeletal muscles 2) Has 2 neurons connected by synapse between C.N.S & organ 2) One neurone between C.N.S and effector organ 3) Efferent preganglionic arises from lateral horn cells. 3) Efferent arises from ventral horn cell. 4) Either acetyl cholin or norepinephrine. 4) Chemical transmitter Acetyl choline

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 August 14, 2015ANS 10

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  Cell bodies of pre-ganglionic nerves give rise to sacral parasympathetic outflow August 14, 2015ANS 11

August 14, 2015ANS 12 Parasympathetic system Nucleus Either Or Pre-ganglionic fibre Post- ganglionic fibre ganglion Effector organ The Parasympathetic ganglia is Either in the viscera (effector organ) Or close to the viscera (effector organ)

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 August 14, 2015ANS 13 E W Nucleus occulomotor Ciliary ganglia Ciliary muscle Pupillary constrictor

Parasympathetic  Pons  From Lacrimal and Salivatory nucleus  Preganglionic 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 August 14, 2015ANS 14

August 14, 2015ANS 15 Pons Facial Nerve Sphenopalatine ganglia Submandibular ganglia Lacrimal gland Submandibular and sublingual glands Parotid gland Otic ganglia IX Inferior salivatory Nucleus Medulla

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  Synapse with post ganglionic nerves in various effector organs in thorax and abdomen August 14, 2015ANS 16

August 14, 2015ANS 17 Dorsal motor nucleus of vagus vagus Heart Lungs Oesophagus Stomach Small intestines Colon Liver, gall bladder, Pancreas, ureters

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  Descending colon  Rectum  Urinary bladder  Lower potions of ureters  External genitalia August 14, 2015ANS 18

ANS Transmission  Chemical transmission  Acetylcholine (Ach)  Nor adrenalin  Dopamine  GnRH  Co-transmitters  VIP released with ach  ATP and neuropeptide Y released with Nor adrenalin August 14, 2015ANS 19

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  Remaining sympathetic postganglionic nerves August 14, 2015ANS 20

Chemical Division of ANS  Adrenal medulla  Essentially sympathetic ganglia  Post-ganglionic nerves have lost the axons  Secretes into blood  Adrenalin  Nor adrenalin  Dopamine August 14, 2015ANS 21

August 14, 2015ANS 22 ANS Neurotransmitters At the ganglia Acetylcholine Both sympathetic and Parasympathetic release Acetylcholine as the neurotransmiter

Postganglionic  Parasympathetic  Release Acetylcholine which can cause both  Excitation  Inhibition  Excitation occur  Smooth muscle of stomach, intestines, bladder, bronchi  On glands August 14, 2015ANS 23

Mechanisms of Ach Action  Ach bind to receptors  Cause depolarization  Ach increase the concentration of ca ++ in ICF  Increase ca ++ conductance  Ca ++ initiate contraction  Acetylcholine bind to membrane receptors  Activate membrane bound G-protein  Guanosine triphosphate (GTP) August 14, 2015ANS 24

Mechanism of Ach Actions  Activation of G-protein  Stimulation of Phospholipase C  Breakdown of Phosphatidylinostol bisphosphate (PIP 2 ) into DAG & IP 3 which then  Initiate membrane and intracellular events leading to muscle contraction August 14, 2015ANS 25

August 14, 2015ANS 26 Ach receptor G-ProteinMembrane bound Lipase Diacylglycerol Protein Kinase Opening Ionic channels Sarcoplasmic Reticulum Inositol Triphosphate Ca ++ ICF Muscle contraction PIP2 DAG + IP3

August 14, 2015ANS 27 Inhibitory effect of acetylcholine Ach K+K+ K+K+ K+K+ K+K+ K+K+ Pr - On the heart SAN, AVN Ach bind to receptor Activation of ionic channels K+ ion efflux Hyperpolarization Decrease Pacemaker activity K+K+ K+K+ K+K+

August 14, 2015ANS 28 Sympathetic Ach Dopamine β α Nor-epinephrine (ATP, Neuropeptide Y) Nor-adrenalin Has got both Excitatory and Inhibitory effects

Noradrenalin  Binding to β receptors  Activates Gs protein  Adenylate cyclase  ATP  cAMP  Increase in cAMP  Activation of protein Kinase  A variety of physiological activities August 14, 2015ANS 29

August 14, 2015ANS 30 Noradrenalin β-receptor Gs-Protein Adenylate Cyclase Opening Ionic channels ATPcAMP Inactive Protein Kinase Active Protein Kinanse Variety of Physiological Functions

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 August 14, 2015ANS 31

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 August 14, 2015ANS 32

Noradrenalin binding to α-Receptors  Two types : α 1 and α 2  Binding to α 1 receptors  Activation of Gs Protein system  Stimulation of Phospholipase C  Breakdown of Phosphatidylinostol bisphosphate (PIP 2 ) into DAG & IP 3 which then  Initiate variety of physiological activities August 14, 2015ANS 33

Noradrenalin on α 2  Activation of Gi Protein  Aadenylate cyclase is inhibited  Decreased concentration of cAMP  Inhibition of variety of Physiologic effects August 14, 2015ANS 34

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  Parasympathetic activity predominates August 14, 2015ANS 35

Dual innervations  Sweat gland, adrenal medulla, pilo-erectors and majority of blood vessels  Receive sympathetic innervation only August 14, 2015ANS 36

August 14, 2015ANS 37 The EYEThe Pupil Radial Muscles Sympathetic Contraction Pupillary dilatation Circular muscles Parasympathetic Contraction Pupillary constriction

August 14, 2015ANS 38 Lens Ciliary muscles Suspensory ligaments Lens Parasympathetic Stimulate ciliary muscles Contraction Ligaments loosen Lens focuses for Near Vision Sympathetic Inhibition of the Muscle Relaxation Suspensory ligaments tighten Lens focuses for far vision

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  Decreases blood flow  Hence decrease in the rate of secretion August 14, 2015ANS 39

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 thick odoriferous secretion August 14, 2015ANS 40

ANS Effects  GIT  Intramural plexuses  Myenteric (Auerbachs)  Meissners (Submucosal plexus)  Parasympathetic nerves end on  Myenteric and Meissners plexuses  Stimulation causes  Excitation of intestinal smooth muscles  Relaxation of sphincters (excitation of dilator components) August 14, 2015ANS 41

ANS Effects  Leads to increased in overall activity  Increased peristalsis  Decrease in gastric and intestinal emptying time  Increase in gastrin and gastric glands secretions August 14, 2015ANS 42

ANS Effects  Sympathetic nerves terminate on  Postganglionic cholinergic nerves  Presynaptic inhibition of Acetylcholine release  Blood vessels  Cause vasoconstriction  Smooth muscles  Increase tone of sphincters  Inhibit motility of GIT August 14, 2015ANS 43

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  Increase the effectiveness of the heart August 14, 2015ANS 44

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 the effectiveness of the heart August 14, 2015ANS 45