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April 19, 2023ANS 1
AUTONOMIC NERVOUS SYSTEM
OrganizationSympathetic
ParasympatheticFunctional Anatomy
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
April 19, 2023ANS 2
Functional Anatomy
Activated by centers located in the Spinal cord Brain stem Hypothalamus Cerebral cortex
April 19, 2023ANS 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
April 19, 2023ANS 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
April 19, 2023ANS 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
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April 19, 2023ANS 7
Dorsal root ganglia
Ventral root
Ganglia chain
Collateral ganglia
White ramus
Gray ramus
Spinal nerve
Pre-ganglionic
Post-ganglionic
April 19, 2023ANS 8
Somatic nervous system
Effector organs
Parasympathetic ganglia
Sympathetic
gangliaPre-ganglionic
Post-ganglionic
Post-
Pre-ganglionic
Adrenal Medulla
catecholamine
Somatic N .S (voluntary)
Autonomic N .S (involuntary)
1) Innervate skeletal muscles 1 (Supply smooth muscles, Cardiac and Glands
2) One neurone between C.N.S and effector organ
2 (Has 2 neurons connected by synapse between C.N.S & organ
3) Efferent arises from ventral horn cell.
3 (Efferent preganglionic arises from lateral horn cells.
4) Chemical transmitter Acetyl choline
4 (Either acetyl cholin or norepinephrine.
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
April 19, 2023ANS 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
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April 19, 2023ANS 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
April 19, 2023ANS 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
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April 19, 2023ANS 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
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April 19, 2023ANS 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
April 19, 2023ANS 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
April 19, 2023ANS 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
April 19, 2023ANS 20
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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April 19, 2023ANS 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
April 19, 2023ANS 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)
April 19, 2023ANS 24
Mechanism of Ach Actions
Activation of G-protein Stimulation of Phospholipase C
Breakdown of Phosphatidylinostol bisphosphate (PIP2) into DAG & IP3 which then Initiate membrane and intracellular events
leading to muscle contraction
April 19, 2023ANS 25
April 19, 2023ANS 26
Ach
receptor G-Protein Membrane bound Lipase
Diacylglycerol
Protein Kinase
Opening Ionic channels
Sarcoplasmic Reticulum
Inositol Triphosphate
Ca++
Ca++
ICFMuscle contraction
PIP2DAG + IP3
April 19, 2023ANS 27
Inhibitory effect of acetylcholine
Ach
K+
K+
K+
K+
K+
Pr -Pr -
On the heart SAN, AVN
Ach bind to receptor
Activation of ionic channels
K+ ion efflux
Hyperpolarization
Decrease Pacemaker activityK+
K+
K+
April 19, 2023ANS 28
Sympathetic
Ach
Dopamineβ
αNor-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
April 19, 2023ANS 29
April 19, 2023ANS 30
Noradrenalin
β-receptor
Gs-Protein Adenylate CyclaseOpening Ionic channels
ATP cAMP
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
April 19, 2023ANS 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
April 19, 2023ANS 32
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
April 19, 2023ANS 33
Noradrenalin on α2
Activation of Gi Protein Aadenylate cyclase is inhibited Decreased concentration of cAMP Inhibition of variety of Physiologic
effects
April 19, 2023ANS 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
April 19, 2023ANS 35
Dual innervations
Sweat gland , adrenal medulla, pilo-erectors and majority of blood vessels Receive sympathetic innervation only
April 19, 2023ANS 36
April 19, 2023ANS 37
The EYE The Pupil
Radial Muscles
•Sympathetic
•Contraction
•Pupillary dilatation
Circular muscles
•Parasympathetic
•Contraction
•Pupillary constriction
April 19, 2023ANS 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
April 19, 2023ANS 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
April 19, 2023ANS 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)
April 19, 2023ANS 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
April 19, 2023ANS 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
April 19, 2023ANS 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
April 19, 2023ANS 44
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