Download Disorders of Autonomic Nervous System

Autonomic Nervous
System
Organization
Sympathetic
Parasympathetic
Functional
May 7, 2017
Anatomy
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Functional Anatomy

ANS control the activity of
Smooth muscles of all organs
 Cardiac muscles
 Secretions of glands


Mediates the neural control of
internal environment

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Blood pressure, GIT motility and
secretions, urinary output, sweating
and temperature control
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Functional Anatomy

Activated by centers located in the
Spinal cord
 Brain stem
 Hypothalamus
 Cerebral cortex

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Functional Anatomy

Customarily subdivided into
Sympathetic
 Parasympathetic


Sympathetic was thought to act

In sympathy with emotions
 Fear,

rage
Parasympathetic was thought to

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Restrain sympathetic promoting
calmness
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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



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Join the spinal nerve
They then leave the spinal nerve via white
ramus communicantes
Join the sympathetic ganglia where
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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
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Dorsal root ganglia
Pre-ganglionic
Ventral root
Spinal nerve
Ganglia chain
Gray ramus
Collateral ganglia
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White ramus
Post-ganglionic
Effector organs
Somatic nervous system
ganglia
Pre-ganglionic
Parasympathetic
Post-
Preganglionic
ganglia
Post-ganglionic
Sympathetic
Adrenal
Medulla
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catecholamine
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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
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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

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Cell bodies of pre-ganglionic nerves give rise
to sacral parasympathetic outflow
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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)
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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
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Ciliary
ganglia
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Parasympathetic

Pons

From Lacrimal and Salivatory nucleus
 Preganglionic


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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
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Sphenopalatine
ganglia
Pons
Lacrimal
gland
Facial Nerve
Submandibular
ganglia
Submandibular
and sublingual
glands
Medulla
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Parotid
gland
Otic ganglia
Inferior
salivatory
Nucleus
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Parasympathetic

From the inferior salivatory nucleus


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Pre-ganglionic fibres join IX to Otic ganglia
Innervate parotid glands
From dorsal motor nucleus of VAGUS
Preganglionic fibres join the vagus nerve

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Synapse with post ganglionic nerves in various
effector organs in thorax and abdomen
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vagus
Heart
Lungs
Dorsal motor
nucleus of
vagus
Oesophagus
Stomach
Small intestines
Colon
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Liver, gall bladder,
Pancreas, ureters
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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





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Descending colon
Rectum
Urinary bladder
Lower potions of ureters
External genitalia
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ANS Transmission

Chemical transmission
Acetylcholine (Ach)
 Nor adrenalin
 Dopamine
 GnRH
 Co-transmitters

 VIP
released with ach
 ATP and neuropeptide Y released with Nor
adrenalin
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Chemical Division of ANS

Cholinergic


All pre-ganglionic neurons
Also included



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Parasympathetic post-ganglionic neurons
Sympathetic neurons which innervate sweat glands
Sympathetic neurons which end on blood vessel to
skeletal muscles causing vasodilatation
Noradrenergic

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Remaining sympathetic postganglionic nerves
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Chemical Division of ANS

Adrenal medulla
Essentially sympathetic ganglia
 Post-ganglionic nerves have lost the
axons
 Secretes into blood

 Adrenalin
 Nor
adrenalin
 Dopamine
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ANS Neurotransmitters
At the ganglia
Acetylcholine
Both sympathetic and
Parasympathetic release
Acetylcholine as the neurotransmiter
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Postganglionic
Parasympathetic
 Release Acetylcholine which can
cause both

Excitation
 Inhibition


Excitation occur
Smooth muscle of stomach, intestines,
bladder, bronchi
 On glands

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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
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Guanosine triphosphate (GTP)
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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
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Ach
receptor
G-Protein
Membrane bound Lipase
DAG + IP3
PIP2
Opening
Ionic
channels
Diacylglycerol
Inositol
Triphosphate
Protein
Kinase
Ca++
Ca++
Muscle
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contraction
ICF
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Sarcoplasmic Reticulum
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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+
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K+
-
K+
Hyperpolarization
K+
Decrease Pacemaker
activity
K+
K+
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Sympathetic
Dopamine
Ach
Nor-epinephrine
(ATP, Neuropeptide Y)
β
α
Nor-adrenalin
Has got both Excitatory and Inhibitory effects
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Noradrenalin
Binding to β receptors
 Activates Gs protein

Adenylate cyclase
 ATP  cAMP
 Increase in cAMP

 Activation
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of protein Kinase
A variety of physiological activities
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Noradrenalin
β-receptor
Gs-Protein
Adenylate Cyclase
Opening
Ionic
channels
ATP
Active Protein
Kinanse
cAMP
Inactive
Protein Kinase
Variety of Physiological
Functions
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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

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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

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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
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Noradrenalin on α2
Activation of Gi Protein
 Adenylate cyclase is inhibited
 Decreased concentration of cAMP
 Inhibition of variety of Physiologic
effects

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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
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Parasympathetic activity predominates
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Dual innervations

Sweat gland , adrenal medulla, piloerectors and majority of blood
vessels

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Receive sympathetic innervation only
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The EYE
The Pupil
Radial Muscles
Circular muscles
•Sympathetic
•Parasympathetic
•Contraction
•Contraction
•Pupillary dilatation
•Pupillary constriction
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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
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ANS Effects On Glands


Nasal, lacrimal, salivary, GIT glands
Strongly stimulated by parasympathetic

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Leads to increased amounts of secretions by
the glands
Sympathetic


Little direct effect
Causes vasoconstriction


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Decreases blood flow
Hence decrease in the rate of secretion
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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
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ANS Effects
 GIT

Intramural plexuses



Myenteric (Auerbachs)
Meissners (Submucosal plexus)
Parasympathetic nerves end on


Myenteric and Meissners plexuses
Stimulation causes

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Excitation of intestinal smooth muscles
Relaxation of sphincters . Aowing rapid propusion
of contents aong the tracts
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ANS Effects

Leads to increased in overall activity
Increased peristalsis
 Decrease in gastric and intestinal
emptying time
 Increase in gastrin and gastric glands
secretions

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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
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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
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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
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