introduction to Autonomic Nervous System consisting of Cholinergic, adrenergic and enteric Nervous system with focus on location of neurotransmitters and broad functions of parasympathetic and sympathetic nervous system.

1. INTRODUCTION TO ANS
Dr. Sachin Gupta
Department Of Pharmacology
UCMS

2. NERVOUS SYSTEM
CENTRAL NERVOUS SYSTEM
Processes, interprets, stores
information
Issues orders to muscles, glands organs
BRAIN
SPINAL CORD
Bridge between Brain &
Peripheral nerves
PERIPHERAL NERVOUS
SYSTEM
Transmits information to &
from CNS

3. PERIPHERAL NERVOUS
SYSTEM
EFFERENT
DIVISION
AUTONOMIC
SYSTEM
Regulates glands,
blood vessels, internal
organs
SYMPATHETIC
Mobilizes body for
action energy output
PARASYMPATHETIC
Conserves energy,
maintains quiet state
ENTERIC
AFFERENT
DIVISION
SOMATIC SYSTEM
Controls skeletal
muscles

4. Autonomic Nervous System
• Sympathetic System prepares an
individual to ‘fight, flight or
fright’
• Parasympathetic System aims at
‘conserving & restoring energy’

5. Autonomic Nervous System
• Autonomic Nervous System is composed of Efferent neurons that
innervates-
• Smooth muscles of viscera
• Cardiac muscle
• Vasculature &
• Exocrine glands.
• Thereby controlling---- digestion, cardiac output, blood flow &
glandular secretions.
• The Autonomic system regulates the everyday requirements of vital
bodily functions without the conscious participation of the mind.

6. Autonomic Nervous System
• Make adjustments to ensure optimal support for body activities
• Operate via subconscious control
• Have viscera as most of their effectors

8. PREDOMINANTLY SYMPATHETIC
INNERVATION-
• Radial muscle of iris
• Smooth muscles of eyelids
• Pilomotor muscle
• Ventricular myocardium
• Bladder neck (trigone)
• Seminal vesicles
• Vas deferens
PREDOMINANTLY PARASYMPATHETIC
INNERVATION-
• Circular muscle of iris
• Ciliary muscle
• Lacrimal glands
• Mucous membrane of git &
bronchial tree
• Pancreatic exocrine glands
• Detrusor muscle of bladder
• Erectile tissue of penis

9. PARASYMPATHETIC
“Rest and digest”
system

10. Role of the Parasympathetic Division
• Concerned with keeping body energy use low
• Involves the D activities – digestion, defecation, and diuresis

11. PARASYMPATHETIC NERVOUS SYSTEM
• Preganglionic parasympathetic axons travel a long distance before
eventually reaching their target ganglia which are located close to or
even within the target end organs.
• The Parasympathetic postganglionic fibers---shorter than
preganglionic fibers.
• Preganglionic fibers--- Myelinated
• Postganglionic fibers---Non-myelinated
(except--- ciliary Parasympathetic postganglionic fibers---
Myelinated)

14. PARASYMPATHETIC NERVOUS SYSTEM
• Also called the CRANIOSACRAL system because all its preganglionic
neurons are located in the nuclei of brain stem or sacral levels of the
spinal cord.
• Cranial nerves III,VII, IX and X
• In lateral horn of gray matter from S2-S4
• Distribution of Parasympathetic fibers is wholly visceral
• Acetylcholine is neurotransmitter at end organ as well as at
preganglionic synapse: “cholinergic”

15. SYMPATHETIC
NERVOUS SYSTEM
• “Fight or flight’’ response
• Release adrenaline and
noradrenaline
• Increases heart rate and blood
pressure
• Increases blood flow to skeletal
muscles
• Inhibits digestive functions

16. SYMPATHETIC NERVOUS SYSTEM
• The preganglionic neurons of Sympathetic Nervous System have their
cell bodies in lateral horn of grey matter of Thoracic & Lumbar regions
(T1-L2/3) of Spinal cord
• Thoracolumbar outflow
• The preganglionic neurons are short in comparison to postganglionic
neuron.
• Preganglionic sympathetic fibers tend to synapse with a large no of
Postganglionic fibers which in turn have a more diffused ramification
at Neuroeffector junction (NEJ)

17. SYMPATHETIC NERVOUS SYSTEM
• Immediately after the spinal
nerve leaves the spinal canal, the
preganglionic sympathetic fibers
leave the spinal nerve & pass
through a white ramus into
paravertebral sympathetic chain
of 22 sympathetic ganglia, which
lie bilaterally on either side of the
spinal column.

18. SYMPATHETIC NERVOUS SYSTEM
• The postganglionic sympathetic neurons thus originate either in one
of the Sympathetic chain ganglia or in one of the peripheral
sympathetic ganglia.
• From either of these two sources, the postganglionic fibers then
travel to their destinations in the various organs.

19. Neurochemical Transmission
• Cholinergic Transmission
• Adrenergic Transmission

20. CHOLINERGIC TRANSMISSION
• ACh- Neurotransmitter in
• All Autonomic Ganglion Synapses (Sympathetic / Parasympathetic)
• All Postganglionic parasympathetic neurons
• Sympathetic neurons innervating sweat glands
• The nerve endings supplying Adrenal medulla
• Most enteric nervous system neurons
• The somatic motor nerve endings supplying skeletal muscles
• Effects of Ach are mediated by NICOTINIC and MUSCARNIC receptors

22. Nicotinic Receptors
• Bind-
• ACh
• Nicotine
• Muscarine (weak affinity)
• Composed of 5 subunits
• Functions as Ligand-gated ion
channel
• When bound to ACh, these
receptors undergo conformational
change that allows entry of Na+
ions, resulting in depolarization of
the effector cell.

23. NICOTINIC
RECEPTORS
NM
NEUROMUSCULAR
JUNCTION
NN
AUTONOMIC
GANGLIA
CNS
ADRENAL MEDULLA

24. NM NN
LOCATION SKELETAL
NEUROMUSCULAR
JUNCTION (NMJ)
postsynaptic
AUTONOMIC GANGLIA
ADRENAL MEDULLA
CNS
MEMBRANE RESPONSE • EXCITATORY
• END PLATE
DEPOLARIZATION
• SKELETAL MUSCLE
CONTRACTION
• EXCITATORY
• DEPOLARIZATION and
FIRING OF
POSTGANGLION
NEURON
• DEPOLARIZATION &
SECRETION OF
CATECHOLAMINES

25. MUSCRINIC RECEPTORS
• Bind---
• ACh
• Muscarine (alkaloid present in certain poisonous mushrooms. It was first
isolated in Amanita muscaria)
• Present at –
• Smooth muscles
• Glands
• G- protein coupled receptors

26. Muscarinic
Receptors
M5
CNS
M4
CNS
M3
SMOOTH
MUSCLE
M2
HEART
M1
CNS

28. M1 M2 M3
LOCATION • CNS(cortex &
hippocampus)
• AUTONOMIC
GANGLIA
• GASTRIC
PARACRINE
CELLS
CARDIAC— SA node
AV node
Atrium
Ventricle
NEURAL- presynaptic
terminals
• EXOCRINE GLANDS
• SMOOTH MUSCLES
• VASCULAR ENDOTHELIUM
FUNCTIONAL
RESPONSE
• EXCITATORY---
• Gastric acid
secretion
• GI motility
• CNS excitation
• INHIBITORY---
• SA node-rate of impulse
generation
• AV node- velocity of conduction
• Atrium-
•  refractory period
• contraction
• Ventricle-  contraction
• Peripheral nerves- ganglionic
transmission
• EXCITATORY---
• Smooth muscle–
contraction
• Glands– secretion

29. ADRENERGIC TRANSMISSION
• With exception of the sweat glands , Norepinephrine is the primary
neurotransmitter in sympathetic ganglionic neurons
• Epinephrine is released from chromaffin cells of adrenal medulla and
acts as a circulating hormone
• Norepinephrine & Epinephrine act via α & β receptors
• Smooth muscle contraction – α1 receptors
• Stimulation of heart – β1 receptors
• Smooth muscle relaxation – β2 receptors
• Lipolysis in brown fat – β3 receptors

31. RECEPTOR LOCATION G-PROTEIN SECOND
MESSENGER
α1 Postsynaptic
Most smooth muscles, salivary glands, liver cells
Gq  IP3
  DAG
α2 Presynaptic on adrenergic or cholinergic nerve
terminals;
Postsynaptic in brain;
β-Pancreatic cells
Vascular smooth muscle (α )
Gi
 cAMP
β1 Postsynaptic at cardiac muscle, Juxtaglomerular
apparatus;
Presynaptic at adrenergic & cholinergic nerve
terminals
Gs
 cAMP
β2 Post- as well as Presynaptic in Bronchi, Coronary
arteries, uterus & smooth muscles; also in
myocardium
Gs
 cAMP
β3 Postsynaptic at adipocytes Gs  cAMP

32. ENTERIC NERVOUS SYSTEM
• The Enteric Nervous System,
considered as the third division of
the ANS, consists of highly organized
neurons situated in the wall of GIT.
• It includes the–
• Myenteric plexus (Auerbach’s plexus)
• Submucus plexus (Meissner’s plexus)
• This network receives preganglionic
fibers from the Parasympathetic &
from the postganglionic Sympathetic
neurons.

33. • Neurons--
• Sensory neurons- Receive information from sensory receptors
• Motor neurons- control gi motility & secretions
• Interneurons- integrate information from sensory neurons & provide it to
enteric motor neurons
• Neurotransmitters--
• Acetylcholine– Excitatory–
• Smooth muscle contraction
• Increase in intestinal secretions
• Release of enteric hormones
• Dilatation of blood vessels
• Norepinephrine– Actions opposite that of Ach
• Other neurotransmitters– Neuropeptide(NP), Substance P(SP),
Serotonin (5HT), Dopamine(DA), Cholecystokinin(CCK)

34. • Enteric Nervous System - functions autonomously
• “BRAIN OF THE GUT”
• Sympathetic & Parasympathetic fibers---communication links
between ANS & CNS
• Sympathetic stimulation–
• Inhibition of GI secretions & motor activities
• Contraction of GI sphincters & blood vessels
• Parasympathetic stimulation-
• Increase motility of intestine
• Relaxes the sphincters

35. CONCLUSION
• The main function of ANS is to maintain the entire body and to also
connect all the nerves
• So basically, it maintains everything we do in our everyday life.
• A thorough knowledge of the Anatomy and Physiology of Autonomic
Nervous System is necessary for having a better understanding of
Autonomic dysfunction & the role of overwhelming number of drugs
having an affect on this system.

36. BIBLIOGRAPHY
1. Principles of pharmacology by HL Sharma and KK Sharma (2nd edition)
2. Basic and clinical pharmacology by Bertram G. Katzung (11th edition)
3. The pharmacological basis of therapeutics by Goodman and Gilman (11th
edition)
4. Lippincott's illustrated reviews: pharmacology (5th edition)
5. Essentials of pharmacology by K D Tripathi (6th edition)
6. Review of Medical Physiology by William F. Ganong (23rd edition)
7. Grey’s Anatomy The anatomical basis of Clinical Practice(40th edition)

37. THANK YOU FOR YOUR
TIME AND ATTENTION