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DR NILESH KATE
MBBS,MDASSOCIATE PROF
ESIC MEDICAL COLLEGE, GULBARGA. DEPT. OF PHYSIOLOGY
AUTONOMIC NERVOUS SYSTEM
OBJECTIVES Anatomical consideration.
Divisions. General organization. The Sympathetic Division The Parasympathetic Division.
Physiological consideration. Neurotransmitters & receptors. Functions of ANS. Relationships Between the Sympathetic and
Parasympathetic Divisions Applied physiology
ORGANIZATION OF THE NERVOUS SYSTEM
BRAINSPINAL CORD
CENTRALNERVOUSSYSTEM (CNS)
PERIPHERALNERVOUS SYSTEM
AFFERENT
NERVES
EFFERENT
NERVES
EXTERO-RECEPTORS
INTERO-RECEPTORS
SOMATIC AUTONOMIC
EFFECTORORGANS
SKELETALMUSCLES
SMOOTH AND CARDIAC MUSCLES AND GLANDS
Autonomic Nervous System (ANS)
Derived from Greek word “autos – self & nomos – control”
An involuntary nervous system that modulates and controls the function of visceral organs.
Since it controls vegetative functions also called as vegetative system.
Divisions of the ANS 2 divisions:
Sympathetic : (fight or flight)
Parasympathetic : Controls daily body
functions Both divisions are
constantly “counteracting” or acting together in “autonomic tone”
Autonomic Nervous System (ANS)
Thursday, December 11, 2014
SOMATIC & AUTONOMIC NERVOUS SYSTEM.
SOMATIC Afferent neuron terminate in
dorsal horn. Interneuron terminates in
ventral horn. Efferent neuron cell body in
ventral horn. Single efferent neuron Innervates skeletal muscles. Neurotransmitter – Ach Activity – excitation. Always voluntary.
ANS Afferent neuron terminate in
intermediolateral horn. Interneuron terminates in
autonomic ganglia. Efferent neuron cell body in
autonomic ganglia. 2 efferent neurons. Innervates smooth muscle,
cardiac muscle , secretory glands. Neurotransmitter – Ach & NE. Activity – Excitation & inhibition. Usually Involuntary.
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Thursday, December 11, 2014
GENERAL ORGANIZATION. Autonomic areas in cerebral hemisphere. Autonomic centers in brain stem. Autonomic centers in spinal cord. Peripheral part of ANS.
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Autonomic areas in cerebral hemisphere.
Limbic system. Prefrontal cortex. Hypothalamus.
Integration of somatic, autonomic & endocrine functions.
Main ganglion of ANS. LIMBIC CORTEX equally important.
Thalamus.
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Autonomic centers in brain stem.
Reticular formation. Gigantocellular nucleus. Parvocellular nuclei.
Visceral nuclei of cranial nerves.
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Visceral nuclei of cranial nerves.
Afferent nucleus. Nucleus of solitary
tract in medulla. Receives through IX &
X. Along with reticular
formation reflex control of RS & CVS function.
Efferent nucleus. Preganglionic fibres of
parasympathetic craniosacral outflow.
Includes- (DES). Dorsal nucleus of vagus. Edinger-vestphal N. Salivary nucleus.
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Autonomic centers in spinal cord.
Intermediolateral grey column of spinal cord.
2 levels. Sympathetic – T-1
to L-3 Parasympathetic –
cranial part - S-2 to S-4.
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Peripheral part of ANS. All autonomic nerves & ganglia. No nerve in the body is totally autonomic.
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Neurons of ANS PREGANGLIONIC NEURON
cell body in brain or spinal cord axon is myelinated type B fiber that extends to
autonomic ganglion POSTGANGLIONIC NEURON
cell body lies outside the CNS in an autonomic ganglion
axon is unmyelinated type C fiber that terminates in a visceral effector
Physiological Effects of the ANS
Hypothalamus
only sympathetic innervations sweat glands, adrenal
medulla, erector pili & many blood vessels
controlled by regulation of the “tone” of the sympathetic system
Rest receive dual innervations
Hypothalamus .
Sympathetic motor ANS Thoracolumber outflow 3 destinations.
Terminate in the ganglia.
Travel up & down & then terminate.
Pass without synapsing & terminate in prevertebral ganglia.
SYMPATHETIC GANGLIA The ganglia of
sympathetic division are classified into three groups.
Para vertebral or sympathetic chain ganglia
Prevertebral or collateral ganglia
Terminal or peripheral ganglia
SYMPATHEIC GANGLIA.
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A
BC-4
C-1
C-2A-1
A-2
A-3
B-1
B-3
B-2
C-3
Sympathetic motor NS Lateral horn
paravertebral ganglia spinal nerve = white communicating ramus (myelinated)
Signals from the ganglion (to the target tissue) travel along unmyelinated fibers = grey communicating ramus
Signals between ganglia along the sympathetic trunk
PARASYMPATHETIC DIVISIONotherwise called
craniosacral outflow because, the fibers of this division arise from brain and sacral segments of spinal cord
The cranial nerves of the parasympathetic division are:
1. Oculomotor (III) nerve2. Facial (VII) nerve3. Glossopharyngeal (IX) nerve4. Vagus(X)nerve)3. Sacral outflow (sacral nerves)
PARASYMPATHETIC
SPINEEFFECTORORGAN
PARASYMPATHETICGANGLIA (NEAR EFFECTOR ORGAN)
TECTAL OR MIDBRAIN LEVEL
The group of cells forming Edinger-Westphal nucleus of Ill cranial nerve gives rise to tectal fibers.
The fibers from this nucleus end in the ciliary ganglion.
The postganglionic fibers from here supply the sphincter pupillae and ciliary muscIe
MIDBRAIN OR TECTAL OUTFLOW.& BULBAR OUTFLOW.
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Autonomic neurotransmitters.
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Cholinergic receptors.
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Adrenergic receptors.Alpha receptors.(α)
α - 1 (VGR) Vascular smooth
muscles of skin & splanchnic region
GIT & bladder sphincters
Radial muscles of Iris.
α -- 2 ( PPFW) Presynaptic nerve
terminal Platelets Fat cells Walls of GIT.
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Adrenergic receptors.Beta receptors.(β)
β -- 1 ( SAV) SA node AV node Ventricular
muscles of heart.
β – 2 (VBWB) Vascular smooth
muscles of skeletal muscles
Bronchial smooth muscle
Walls of GIT Bladder.
β – 3
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Differences in Sympatheticand Parasympathetic Divisions
Comparison of some effects of sympathetic & parasympathetic branches
Sympathetic nervous Sympathetic nervous systemsystem
Parasympathetic nervous Parasympathetic nervous systemsystem
increases cardiac outputincreases cardiac output decreases cardiac outputdecreases cardiac output
increases blood pressureincreases blood pressure decreases blood pressuredecreases blood pressure
dilates bronchiolesdilates bronchioles constrict bronchiolesconstrict bronchioles
increases ventilation rateincreases ventilation rate decreases ventilation ratedecreases ventilation rate
dilates pupils dilates pupils constrict pupilconstrict pupil
Comparison of some effects of sympathetic & parasympathetic branches
Sympathetic nervous Sympathetic nervous systemsystem
Parasympathetic nervous Parasympathetic nervous systemsystem
contracts anal & bladder contracts anal & bladder sphincterssphincters
relaxes anal & bladder relaxes anal & bladder sphincterssphincters
contracts erector pili contracts erector pili musclesmuscles
no comparable effectno comparable effect
increases sweat productionincreases sweat production no comparable effectno comparable effect
no comparable effectno comparable effect increases secretion of tearsincreases secretion of tears
Autonomic ReflexesCardiovascular:
- baroreceptor reflex:It is stretch reflex in the main arteries such as carotid artery to detect the blood pressure
Gastrointestinal:The receptors in the nose and mouth send a signal to parasympathetic to notify the glands of mouth & stomach to secrete the digestive juices
Autonomic Reflexes Urinary Bladder:
- Initiate the micturation by parasympathetic innervations
Sexual reflexes:- erection by parasympathetic- ejaculation by sympathetic
The sympathetic activation often occurs in a mass discharge such as in fright or severe pain “fight or fright”(sympathetic stress response)
Functions of ANS Mediate neuronal regulation of internal
environment Coordinate bodily function necessary for
survival Regulate removal of waste products from the
body Prepare the body for normal and life-
threatening stress Effected via control over smooth and heart M.
and glands “autonomic” = self-governing
The Race Horse and the Cow
Sympathetic Parasympathetic
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Sympathetic Nervous System (SNS)
Operates continuously to modulate the functions of many organ systems e.g; heart, blood vessels, GIT, bronchi and sweat glands
Stressful stimulation activates SNS leads to a response known as “fight or flight”: increased arterial pressure, blood flow, blood glucose, metabolic rate and mental activity
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Applied aspects. Autonomic drugs.
Autonomic failure.
Autonomic function tests.
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Autonomic drugs. Mimetic Lytic or Blockers. So……………..
Sympathomimetic Sympatholytic Parasympathomimetic Parasympatholytic.
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SYMPATHOMIMETIC DRUGS Directly acting.
Act directly on alpha & beta adrenergic receptors.
E.g.— Adrenaline Nor adrenaline Phenylnephrine.
Indirectly acting. (enhancing action of NE) displacing NE from
storage sites. – amphetamine.
Inhibiting reuptake. – imipramine.
MAO inhibitors.
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SYMPATHETIC BLOCKERSSYMPATHETIC BLOCKERS Prevention of synthesis & storage of NE. –
Reserpine. Prevention of release of NE. – Guanethidine. Blockage of receptors.
Alpha -- Phentolamine Beta – Propranolol, Metoprolol.
Blockage of transmission of nerve impulse. – Hexamethonium.
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Parasympathomimetic drugs. Drugs acting on muscarinic receptors. –
Pilocarpine, Methacholine.
Prolonging action of Ach –Neostigmine, Physostigmine.
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Parasympathetic blockers. Drugs blocking Muscarinic receptors.
Atropine Homatropine Scopolamine.
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Autonomic failure. Primary
Cause not known. Autonomic
neuronal degeneration.
Secondary Secondary to
some cause. Most common
cause.--Diabetes mellitus.
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Autonomic failure. Features.
CVS – Orthostatic hypotension , tachycardia. Sudomotor – anhidrosis, heat intolerance. GIT – constipation , diarrhea & dysphagia. Urinary – nocturia, frequency, urgency,
incontinence & retention. Reproductive – erectile & ejaculation failure.
Thursday, December 11, 2014
Disorders of the Autonomic Nervous System: Raynaud’s Disease
Raynaud’s disease – characterized by constriction of blood vessels Provoked by exposure to cold or by
emotional stress
Disorders of the Autonomic Nervous System: Hypertension
Hypertension – high blood pressure Can result from overactive
sympathetic vasoconstriction
Disorders of the Autonomic Nervous System: Achalasia of the Cardia
Achalasia of the cardia Defect in the autonomic
innervation of the esophagus
Mass reflex reactionMass reflex reaction Uncontrolled activation of Uncontrolled activation of
autonomic and somatic motor autonomic and somatic motor neuronsneurons
Affects quadriplegics and Affects quadriplegics and paraplegicsparaplegics
Autonomic function tests. Cardiovascular Pupillary Sudomotor. Bladder.
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Autonomic function tests. Cardiovascular.
Valsalva manoeuvre. Heart rate variation
during deep breathing. Heart rate response to
standing. blood pressure
response to standing. Blood pressure
response to sustained handgrip.
Sudomotor. Evaluation of sweating
response to increased body temperature.
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Autonomic function tests. Pupillary function.
Cocaine test.Normal pupil dilateHorner’s pupil – not Adrenaline test.Horner’s pupil dilate
more than normal.
Bladder function Absense of
accommodation. Absense or poor
voluntary bladder contraction.
Thursday, December 11, 2014
RECAP Anatomical consideration.
Divisions. General organization. The Sympathetic Division The Parasympathetic Division.
Physiological consideration. Neurotransmitters & receptors. Functions of ANS. Relationships Between the Sympathetic and
Parasympathetic Divisions Applied physiology
Thank You