Autonomic Nervous System

1. AUTONOMIC
NERVOUS SYSTEM
DR. SARAN AJAY
DEPT. OF PHYSIOLOGY, GMCM

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Complementary, my dear Watson!

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5. Autonomicsystemmakesinvoluntaryfinetuning
adjustmentstoyourbodyaccordingtothesignalsyour
CNSispickingup.
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Specific Learning Objectives
•Introduction to ANS
•General Organisation of ANS
•Sympathetic System
•Parasympathetic System
•Neurotransmitters and Receptors in ANS
•Responses of various organs to autonomic nerve impulses
•Drugs acting on ANS
•Applied Physiology
•Summary
DEPT. OF PHYSIOLOGY, GMCM

7. Autonomic Nervous System
•Controls visceral functions.
•Maintains homeostasis.
•Rapidity and Intensity
Autonomic(adj) /ɔːtəˈnɒmɪk/
self governing, functionally independent
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8. OUTPUT FROM CNS
Somatic Motor
Neurons
Skeletal Muscle
Autonomic Motor
Neurons
Smooth Muscle
Cardiac Muscle
Secretory Epithelia
Exocrine Glands
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9. How does the ANS work?
Operates via the visceral reflex.
Viscera
Integration
center in CNS
Receptor Afferent Pathway
Efferent Pathway
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10. Divisions of ANS
1.SympatheticNervous System
2.ParasympatheticNervous System
3.Enteric Nervous System
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Specific Learning Objectives
•Introduction to ANS
•General Organisation of ANS
•Sympathetic System
•Parasympathetic System
•Neurotransmitters and Receptors in ANS
•Responses of various organs to autonomic nerve impulses
•Drugs acting on ANS
•Applied Physiology
•Summary
DEPT. OF PHYSIOLOGY, GMCM

12. Peripheral motor portions of ANS are made up of twoneurons.
1.Preganglionic Neuron
2.Post Ganglionic Neuron
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14. ANS General Organization
Pre-ganglionic
Neuron
Post-ganglionic
Neuron
Target
Organ
Located in CNS Located in
peripheral ganglia
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15. Sympathetic and Parasympathetic system innervate target
tissues by two synapse pathway.
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17. Axons of the preganglionic neuronAxons of the postganglionic neuron
Myelinated, Small diameter
Slowly conducting BFibers
Axons diverge onto the
postganglionic neuron
Unmyelinated
CFibers
Axons terminate on visceral
effectors
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Specific Learning Objectives
•Introduction to ANS
•General Organisation of ANS
•Sympathetic System
•Parasympathetic System
•Neurotransmitters and Receptors in ANS
•Responses of various organs to autonomic nerve impulses
•Drugs acting on ANS
•Applied Physiology
•Summary
DEPT. OF PHYSIOLOGY, GMCM

19. Sympathetic Nervous System
•Cell bodies of the preganglionic neurons are in the
spinal cord.
•Intermediolateral column/ lateral horn
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21. Sympathetic Nervous System
•Cell bodies of the preganglionic neurons in the spinal cord.
•Intermediolateral column/ lateral horn
•Between T1and L3/L4
•Thoracolumbar division of ANS
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22. Segmental Distribution of Sympathetic Fibers
T1 Head
T2 Neck
T3-T6 Thorax
T7-T11 Abdomen
T12, Lumbar Into Legs
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Sensory
afferent
Prevertebral
Ganglion

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25. Sympathetic Division
•Preganglionic axons exit through the ventral root.
•Along with axons from somatic motor neurons.
•After entering spinal nerve, sympathetic efferent diverge
from somatic motor axons.
•Enter White Rami Communicans
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26. Preganglionic
fibers
Paravertebral Ganglia
Prevertebral Ganglia
Direct Termination
Post ganglionic neurons
Post ganglionic neurons
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28. 1. Paravertebral Ganglia
•Extend from neck to coccyx
•One on either side of spinal cord
•Connected to each other
•Adjacent ganglia fuse
•e.g. –cervical, thoracic and lumbar ganglia
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29. In paravertebral ganglia, axons of preganglionic neurons
1.Synapse within same segmental paravertebral ganglia
2.Synapse within neighboringparavertebral ganglia
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30. 2. Prevertebral Ganglia
•Lies in front of aorta and its major branches
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32. 2. Prevertebral Ganglia
•Lies in front of aorta and its major branches
3. Terminate directly
•On effector organ –adrenal gland
•Postganglionic cell are secretory
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33. •Preganglionic sympathetic fibers without synapsing reach
adrenal medulla.
•The preganglionic fibres end on the secretory cells in
adrenal medulla
•The cells in adrenal medulla is postganglionic neurons
that lost their axon to become secretory cells.
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35. Axons of post ganglionic neurons leave the chain ganglia
•Re-enter spinal nerve via gray rami communicans
•Distributed to effectors in areas supplied by spinal nerves
•To smooth muscles, sweat glands
•Enter thoracic cavity
•Terminate on visceral organs
•Fibers from prevertebral ganglia terminate in visceral targets
1
2
3
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Specific Learning Objectives
•Introduction to ANS
•General Organisation of ANS
•Sympathetic System
•Parasympathetic System
•Neurotransmitters and Receptors in ANS
•Responses of various organs to autonomic nerve impulses
•Drugs acting on ANS
•Applied Physiology
•Summary
DEPT. OF PHYSIOLOGY, GMCM

38. Parasympathetic Nervous System
•Preganglionic Neurons are located in
1.Cranial Nerve Nuclei III, VII, IX and X
2.IML of the sacral spinal cord
•Craniosacral outflow
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39. Cranial Outflow
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40. •Parasympathetic sacral outflow supplies the pelvic
viscera via the sacral spinal nerves (2
th
to 4
th
).
•Fibers are in pelvic nerves.
•Post ganglionic neurons located in terminal ganglia.
Sacral Outflow
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41. •Ganglia -peripherally located, often within the walls
of target organs
•Distributedto
1.Descending colon, Rectum
2.Urinary bladder, lower portions of ureter
3.External genitalia
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Specific Learning Objectives
•Introduction to ANS
•General Organisation of ANS
•Sympathetic System
•Parasympathetic System
•Neurotransmitters and Receptors in ANS
•Responses of various organs to autonomic nerve impulses
•Drugs acting on ANS
•Applied Physiology
•Summary
DEPT. OF PHYSIOLOGY, GMCM

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45. •Varicosities/ bulbous expansions on axon
•Forms synapse enpassant
•Wider distribution of autonomic output
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46. Synapse enpassant
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47. Neurotransmitters and Receptors in ANS
•The principal transmitters are Acetylcholine (Ach) and
Norepinephrine (NE).
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48. 1.Betweenpreganglionic and postganglionic neurons
(in both sympathetic and parasympathetic system)
•Neurotransmitter - Acetyl Choline
•Receptor - Nicotinic Receptor (N
2)
(Ligand Gated Channel)
•Other sites - Neuromuscular Junction (N
1)
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49. 2.Betweenpostganglionic parasympathetic neurons
and target cell
•Neurotransmitter - Acetyl Choline
•Receptor - Muscarinic Receptor on target
(GPCR)
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50. Binding of AChon muscarinic receptor can either stimulate
or inhibitfunctions of target cells.
Receptor Mechanism of Action
M
1, M
3, M
5 (+)PL C, ↑ IP
3 DAG
M
2, M
4 (-)adenyl cyclase, ↓ cAMP
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51. 3.Betweenpostganglionic sympathetic neurons
and target cell
•Neurotransmitter - Norepinephrine
•Receptor - Adrenergic Receptors on
target (GPCR)
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52. Receptor Mechanism of Action
α
1 (+)PL C, ↑ IP
3 DAG
α
2 ↓ cAMP
β
1 ↑ cAMP
β
2 ↑ cAMP
β
3 ↑ cAMP
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53. 4.Exceptions
Sympathetic postganglionic fibers innervating
•Sweat Glands
•Piloerector muscles of hair
•Blood vessels in some skeletal muscle
ACh
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Specific Learning Objectives
•Introduction to ANS
•General Organisation of ANS
•Sympathetic System
•Parasympathetic System
•Neurotransmitters and Receptors in ANS
•Responses of various organs to autonomic nerve impulses
•Drugs acting on ANS
•Applied Physiology
•Summary
DEPT. OF PHYSIOLOGY, GMCM

56. Organs with
Dual innervation with antagonistic effects
e.g. Heart, Digestive tract, Urinary Bladder, Airways
Responses of various organs to autonomic
nerve impulses
1
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57. Complementary Sympathetic and Parasympathetic
Action
e.g. Salivary glands
2 Divisions act synergistically/ in cooperative manner
e.g. Control of pupil diameter, control of sexual function
2
3
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58. Organsinnervatedbyonlyonedivision
e.g.Adrenalgland,mostbloodvessels,piloerector
musclesinskin,sweatglands–onlysympathetic
supply
Lacrimalmuscle,ciliarymuscleandsublingual
salivaryglands–onlyparasympatheticsupply
4
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59. Sympathetic output can be
1.Selectivefor a specific target organ
2.Massiveand non specific (fight or flight response)
Sympathetic Response
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60. Fight or Flight Response
•Walter B Cannon
•Fear, Stress etc. →massive output + PS activity ceases
•↑ HR, BP, pupil dilation etc.
•Mechanism of survival
•Catabolic NS
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61. •Concerned with vegetative aspects of day to day living.
•Anabolic NS
Parasympathetic Response
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63. Effector Organ Parasympathetic
Sympathetic
Receptor Response
Eye
Radial muscle of iris - α1 Contraction
(Mydriasis)
Sphincter muscle of iris Contraction
(Miosis)
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64. Effector Organ Parasympathetic
Sympathetic
Receptor Response
Heart
SA Node ↓HR β1 ↑HR
Atria and ventricle ↓ atrial contractility β1, β2 ↑Contractility
AV Node and Purkunjee ↓ conduction velocity β1 ↑ conduction
velocity
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65. Effector Organ Parasympathetic
Sympathetic
Receptor Response
Stomach and Intestine
Motility and Tone ↑ α1,α2,β2 ↓
Sphincters Relaxation α1 Contraction
Secretion Stimulation - -
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66. Effector Organ Parasympathetic
Sympathetic
Receptor Response
Bronchial Smooth
Muscle
Contraction β2 Relaxation
Urinary Bladder
Detrusor Contraction β2 Relaxation
Sphincter Relaxation α1 Contraction
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67. Effector Organ Parasympathetic
Sympathetic
Receptor Response
Uterus (pregnant) α1/β2 Contraction/
Relaxation
Male sex Organs Erection α1 Ejaculation
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68. Effector Organ Parasympathetic Sympathetic
Receptor Response
Salivary Gland Profuse watery
secretion
α1/ β Thick,
viscous
secretion,
amylase
secretion
Lacrimal Gland Secretion - -
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69. DEPT. OF PHYSIOLOGY, GMCM 70
Specific Learning Objectives
•Introduction to ANS
•General Organisation of ANS
•Sympathetic System
•Parasympathetic System
•Neurotransmitters and Receptors in ANS
•Responses of various organs to autonomic nerve impulses
•Drugs acting on ANS
•Applied Physiology
•Summary
DEPT. OF PHYSIOLOGY, GMCM

70. 1.Sympathomimetic drugs
•Stimulate specific adrenergic receptors
•e.g. Phenylephrine, Isoproterenol, Albuterol
Drugs acting on ANS
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71. 2. Parasympathomimetic drugs
•e.g. Pilocarpine, Methacholine
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Specific Learning Objectives
•Introduction to ANS
•General Organisation of ANS
•Sympathetic System
•Parasympathetic System
•Neurotransmitters and Receptors in ANS
•Responses of various organs to autonomic nerve impulses
•Drugs acting on ANS
•Applied Physiology
•Summary
DEPT. OF PHYSIOLOGY, GMCM

73. Horner’s Syndrome
Characterized by unilateral
1.Ptosis
2.Miosis
3.Anhidrosis
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74. •Loss of sympathetic innervation on one side of the face
•Causes
1.Malignancy of cervical Lymph Nodes
2.Pancoast Tumor
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Specific Learning Objectives
•Introduction to ANS
•General Organisation of ANS
•Sympathetic System
•Parasympathetic System
•Neurotransmitters and Receptors in ANS
•Responses of various organs to autonomic nerve impulses
•Drugs acting on ANS
•Applied Physiology
•Summary
DEPT. OF PHYSIOLOGY, GMCM

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77. SYMP Pre
Ganglionic
SYMP Post
Ganglionic
PARASYMP Pre
Ganglionic
PARASYMP Post
Ganglionic
Location of
cell body
Myelination
NT
Post Synaptic
Receptor
IML of SC
T1 to
L3/L4
Pre + Para
Vertebral
Ganglion
Brainstem
Sacral SC
Terminal
ganglion
near target
Yes YesNo No
ACh ACh AChNE
Nicotinic NicotinicAdrenergic Muscarinic
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79. [email protected]
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