8. Autonomic nervousAutonomic nervous
system (ANS)system (ANS)
Part of nervous system that controls
visceral functions
• Cardiac muscle, smooth muscle (blood
vessels, GIT, urinary bladder etc) glands
(secretions)
Not under voluntary control
9. Anatomy of the Motor Output inAnatomy of the Motor Output in
Sympathetic and ParasympatheticSympathetic and Parasympathetic
nervesnerves
10. Autonomic nervous system
• Two neuron chain from CNS to effector
organ
• Pre and postganglionic neurons
Somatic nervous system
• Single neuron connects CNS with effector
organ
12. Autonomic nervousAutonomic nervous
system (ANS)system (ANS)
Ganglion
• Cluster of neurons outside CNS
• Autonomic ganglion
oSite of synapse between autonomic pre &
post ganglionic fibers
oParavertebral ganglionic chain
oPrevertebral (collateral) ganglia
13. Autonomic nervousAutonomic nervous
system (ANS)system (ANS)
Cell body of preganlionic neuron
• Lies in CNS
oSpinal cord (sympathetic division)
oBrain and spinal cord (parasympathetic
division)
Cell body of postganglionic neuron
• Lies in autonomic ganglia
14. Autonomic nervousAutonomic nervous
system (ANS)system (ANS)
Sympathetic nervouss system
• Short preganlionic fibers
• Long postganglionic fibers
Parasympathetic nervous system
• Long preganlionic fibers
• Short postganglionic fibers
17. Autonomic nervousAutonomic nervous
system (ANS)system (ANS)
All preganlionic fibers are cholinergic
All postganglionic parasympathetic
fibers are cholinergic
Almost all postganglionic
sympathetic fibers are adrenergic
• postganglionic sympathetic fibers to
sweat glands and piloerector muscles
are cholinergic
18. Autonomic nervousAutonomic nervous
system (ANS)system (ANS)
Receptors
• Nicotinic receptors -in autonomic ganglia
• Muscarinic receptors -in effector organs
stimulated by postganglionic cholinergic
fibers
• Adrenergic receptors -in effector organs
stimulated by postganglionic adrenergic
fibers
oα adrenergic receptors (α1 and α2)
oΒ adrenergic receptors (β1 and β2)
19. Muscarinic receptors in the parasympathetic
system β M1 M3, M5 M2, M5
AcetylcholineAcetylcholine
Neuroscience, Sinauer Asssoc., Inc
25. Sympathetic NS
NE, EPINEPHRINE
Stimulated Inhibited
All the tissues
α1 A.R
Except
Heart, JGA, Lipocytes
Β1 A.R
All the tissues
β2 A.R
Except
Presynaptic Nerve Endings
Platelets, some part of GIT
α2 AR
36. Adrenal medulla
Stimulation of sympathetic innervation of
adrenal medulla causes release of large
quantities of epinephrine (80%) and
norepinephrine (20%)
Effect lasts 5-10 times longer
Sympathetic tone caused by basal
secretion from adrenal medulla
(.2 µg/kg/min Epinephrine and .05
µg/kg/min of noreepineohrine
37. Adrenal MedullaAdrenal Medulla
• Epinephrine affects
– more on beta
–Less on alpha
–More metabolic effect
• Adrenal medulla provides back
up for sympathetic function in
addition to normal channel of
sympathetic nerves
40. Autonomic nervousAutonomic nervous
system (ANS)system (ANS)
Dual supply
• All the viscera supplied by both the
divisions of ANS
• Sympathovagal balance determines the
ultimate function of the viscera
41. Functions of ANSFunctions of ANS
Sympathetic and parasympathetic
components of ANS function to
maintain homeostasis at
subconscious level -maintain stable
internal environment
42. α1 receptors
•vascular smooth muscle, on GI and bladder sphincters
and radial muscle of the eye. causes excitation
(contraction)
α2 receptors
•presynaptic nerve terminals, platelets, fat cells, walls of
GI tract causes inhibition (relaxation, dilation)
β1 receptors
•SA node, AV node, ventricular muscle of heart
• produces excitation, increases heart rate, contractility,
and conduction velocity
β2 receptors
•vascular smooth muscle of skeletal muscle, bronchioles,
walls of GI tract and bladder
•produces relaxation: dilation of vascular smooth muscle
and relaxation of bladder, bronchioles
Location of specific adrenergic receptors
45. Sweat glandsSweat glands
• Sympathetic fires supply them. If
stimulated copious sweating
• Acetylcholine is neurotransmiiter
except palms and soles which are
adrenergic
• Overall control is parasympathetic via
hypothalamus so sweating could be
called parasympathetic function
46. Stimulus RateStimulus Rate
• Low frequency required to fully
activate ANS as compared to
Skeletal nervous system
47. Sympathetic and
parasympathetic tone”
Continual basal activity of the
sympathetic
and parasympathetic systems allows
either branch
of the ANS to increase or decrease its
activity
of a stimulated organ
If tone lost intrinsic compensation in
some time
49. Enteric Nervous
System
Gastrointestinal tract nervous system
Myenteric plexus
(auberbach’s)
Meissner’s plexus
(submucosal)The Enteric Nervous System can function
on its own but is most often controlled by the
sympathetic and parasympathetic systems
Contains more neurons than the spinal cord and uses
many different neurotransmitters and neuromodulator
approaching the complexity of the CNS
51. Alarm or Stress response
Mass discharge of sympathetic system allows
the body to make maximal use of its resource
thereby enhancing its chances for survival
•pupilary dilation
•increase heart rate and strength of contracti
•increase blood pressure
•increase blood flow to active muscles
•increase rates of metabolism
•increased blood glucose concentration
•increased muscle strength
•increase mental activity
52. Exceptions of isolatedExceptions of isolated
Function inFunction in
SympatheicSympatheic
• SWEATING
• Muscle activiy in animals
• Local reflexes (skin heat)
• Many GIT reflexes
53. Parasympathetic System Usually CausesParasympathetic System Usually Causes
specific localized responsesspecific localized responses
Parasympathetic cardiovascular reflexes
usually
act only on the heart to control its rate of
beating
Examples:Examples:
timulation of secretion in mouth while not
ffecting stomach, although sometimes they occ
ogether
In Contrast……...
54. Hypothalamus is critical
for coordinating autonomic
output.
It projects to several
brainstem nuclei and
coordinates autonomic
function with feeding,
thermoreg.,water balance,
circadium rhythm, sex
drive, etc., and thus plays a
dominant role in
integrating higher cortical
areas and autonomic
function.panic attacks, emotional stress,
cognitive activity
Medullary, pontine and mesencephalicMedullary, pontine and mesencephalic
control of ANS and their supervision bycontrol of ANS and their supervision by
HYPOTHALAMUSHYPOTHALAMUS
55. Functions of ANSFunctions of ANS
Sympathetic nervous system
• Prepares and mobilizes the body in
emergency (fright, fear, pain, rage etc)
• Fight or flight reaction
56. Functions of ANSFunctions of ANS
Parasympathetic nervous system
• Conserves and stores energy -puts the
body in cool and calm state
57. Functions of ANSFunctions of ANS
Sympathetic Parasympathetic
Heart
↑ heart rate
↑ force of contraction
Heart
↓ heart rate
↓force of contraction
Blood vessels
Constriction
Blood vessels
No effect
Lungs
Bronchodilation
Lungs
Bronchoconstriction
GIT
↓ motility
Sphincter contraction
Decreased secretions
GIT
↑ motility
Sphincter relaxation
Increased secretions
58. Functions of ANSFunctions of ANS
Sympathetic Parasympathetic
Salivary glands
Stimulates secretion
Salivary glands
Stimulates secretion
Sweat glands
Copious secretion
Sweat glands
Sweating on palms only
Eye
Papillary dilation
Flattening of lens
Eye
Papillary constriction
Thickening of lens
Urinary bladder
Relaxation of bladder wall
Sphincter contraction
Urinary bladder
Contraction of bladder wall
Sphincter relaxation
59. Autonomic nervousAutonomic nervous
system (ANS)system (ANS)
Mass discharge of sympathetic
system
• Simultaneous discharge of all portions of
sympathetic nervous system as a unit
• Due to activation of hypothalamus as a
result of fright, fear or pain
• Also called alarm or stress response of
the body
• Prepares the body for ‘emergency’
60. Autonomic nervousAutonomic nervous
system (ANS)system (ANS)
Mass discharge of sympathetic system
• Increased BP
• Increased blood flow to active muscles
• Less blood flow to skin and GIT
• Increased rate of cellular metabolism
• Increased glycogenolysis and lipolysis
• Increased muscle strength
• Increased mental activity
• Papillary dilation
• Increased respiratory rate
61. Autonomic nervousAutonomic nervous
system (ANS)system (ANS)
Sympathetic and parasympathetic
tone
• Basal rate of discharge
• Allows single division to adjust
stimulation level of an organ
oSympathetic tone to blood vessels