1. AUTONOMIC
NERVOUS
SYSTEM
DR NILESH KATE
MBBS,MD
ASSOCIATE PROF
ESIC MEDICAL COLLEGE, GULBARGA.
DEPT. OF PHYSIOLOGY
2. 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
3. ORGANIZATION OF THE NERVOUS
SYSTEM
BRAIN
SPINAL CORD
CENTRAL
NERVOUS
SYSTEM (CNS)
PERIPHERAL
NERVOUS
SYSTEM
AFFERENT
NERVES
EFFERENT
NERVES
EXTERO-RECEPTORS
INTERO-RECEPTORS
SOMATIC AUTONOMIC
EFFECTOR
ORGANS
SKELETAL
MUSCLES
SMOOTH AND
CARDIAC MUSCLES
AND GLANDS
4. 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.
5. 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”
9. 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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10. 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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11. Autonomic centers in brain
stem.
Reticular formation.
Gigantocellular nucleus.
Parvocellular nuclei.
Visceral nuclei of cranial nerves.
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12. 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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13. 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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14. Peripheral part of ANS.
All autonomic nerves & ganglia.
No nerve in the body is totally autonomic.
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15. 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
16. 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 .
17. Sympathetic motor ANS
Thoracolumber outflow
3 destinations.
Terminate in the
ganglia.
Travel up & down &
then terminate.
Pass without
synapsing &
terminate in
prevertebral ganglia.
18. 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
20. 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
21. PARASYMPATHETIC DIVISION
otherwise 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) nerve
2. Facial (VII) nerve
3. Glossopharyngeal (IX) nerve
4. Vagus(X)nerve)
3. Sacral outflow (sacral nerves)
23. 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
24. MIDBRAIN OR TECTAL OUTFLOW.
& BULBAR OUTFLOW.
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32. Autonomic Reflexes
Cardiovascular:
- 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
33. 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)
34. 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
38. 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
42. 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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43. SSYYMMPPAATTHHEETTIICC BBLLOOCCKKEERRSS
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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44. Parasympathomimetic drugs.
Drugs acting on muscarinic receptors. –
Pilocarpine, Methacholine.
Prolonging action of Ach –Neostigmine,
Physostigmine.
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46. Autonomic failure.
Primary
Cause not known.
Autonomic
neuronal
degeneration.
Secondary
Secondary to
some cause.
Most common
cause.--Diabetes
mellitus.
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48. 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
49. Disorders of the Autonomic Nervous
System: Hypertension
Hypertension – high blood pressure
Can result from overactive
sympathetic vasoconstriction
50. Disorders of the Autonomic Nervous
System: Achalasia of the Cardia
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UUnnccoonnttrroolllleedd aaccttiivvaattiioonn ooff
aauuttoonnoommiicc aanndd ssoommaattiicc mmoottoorr
nneeuurroonnss
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Achalasia of the cardia
Defect in the autonomic
innervation of the esophagus
51. Autonomic function tests.
Cardiovascular
Pupillary
Sudomotor.
Bladder.
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52. 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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53. Autonomic function tests.
Pupillary function.
Cocaine test.
Normal pupil dilate
Horner’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
54. 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
The ANS is one of the most sophisticated control systems known to man. It is primarily involved in maintaining the homeostatic state of the organism while allowing adaptation to changes in conditions, sometimes even severe changes.
Contrary to the somatic division of the CNS is it a totally unconscious activity. It also involves a sophisticated interplay of chemical and neural signals (see previous lecture).
The parasympathetic ganglia are near the effector organ.