The document provides an overview of the autonomic nervous system, including its divisions into the sympathetic and parasympathetic nervous systems. It describes the central and peripheral nervous systems and their roles in sensory input and motor output. It explains that the autonomic nervous system is responsible for involuntary functions like heart rate and blood pressure control. It compares the sympathetic and parasympathetic systems in terms of their central roots of origin, locations of ganglia, neurotransmitters used, and effects on different organs.

1. Autonomic Nervous System
Pharmacology
Lecture 1
The Autonomic Nervous System: Introduction
Dr. Mohit Kulmi

2. CENTRAL NERVOUS SYSTEM (CNS)
• Brain and spinal cord:
• receives and processes incoming sensory information and
responds by sending out signals that initiate or modify a
process
PERIPHERAL NERVOUS SYSTEM OR PNS
Includes all the neurons and ganglia found outside the CNS
Afferent: sensory input to CNS
• Afferent neurons carry sensory input from the periphery to the
CNS and modify motor output through the reflex arc.
Efferent: motor output from CNS
• Efferent neurons carry motor signals from the CNS to the
peripheral areas of the body.

3. Efferent Division
The efferent portion of the PNS is further divided into two major
functional subdivisions,
1. Somatic (SNS):
• one motor neuron innervates the skeletal muscles and control
voluntary (consciously) functions; movement, respiration and
posture.
2. Autonomous nervous system (ANS):
• The ANS is the major involuntary portion of the NS
• is responsible for automatic, unconscious bodily function, such as
• control of HR and BP and both GIT and GUT functions.

4. Nervous System
Two main divisions
I. CNS
• Brain & spinal
cord
II. PNS
1. Afferent (sensory)
2. Efferent (motor)
• Somatic & ANS

6. Key steps in neurotransmission

7. Cholinergic Neurotransmission
Synthesis
Storage
Release
Binding
Degradation
Recycling of choline

9. Central roots of origin
Parasympathetic Division– also called
the craniosacral division
• The preganglionic fibers arise
from the cranial nerve nuclei III,
VII, IX, and X and sacral region
(usually S2-S4) of the spinal cord,
and synapse in ganglia close to the
effector organ.
• Thus, in contrast to the
sympathetic system, the
preganglionic fibers are long, and
the postganglionic ones are short.
Sympathetic Division – also called
the thoracolumbar division
• The preganglionic fibers arise
from the thoracic (T1-T12) and
lumbar (L1-L5) regions of the
spinal cord, and they synapse in
paravertebral ganglia close and
parallel to the vertebral column.
Postganglionic axons lead to an
effector organ.

11. DIFFERENCES BETWEEN SYMPATHETIC AND
PARASYMPATHETIC NERVOUS SYSTEM

12. Location of Ganglia
• Both the PANS and SANS have
relay station, or ganglia, between
the CNS and the end organ, but the
somatic system does not;
• The ANS, carries nerve impulses
by
• a preganglionic fiber that leaves
the CNS,
• a postganglionic fiber that
innervates the effector.

13. GENERAL OUTLAY OF EFFERENT NERVOUS SYSTEM :

14. Adrenal medulla
the adrenal medulla,
• like the sympathetic ganglia, receives preganglionic fibers
from the sympathetic system.
• Lacking the axons,
• in response to stimulation by Ach, influences other organs by
secreting the epinephrine and lesser amounts of nor-
epinepherine into the blood.

15. Functions of the Sympathetic Nervous System
• Is normally active, even at rest; however, it assumes a
dominant role when the body becomes stressed (trauma, fear,
hypoglycemia cold or exercise).
• Fight or Flight – Protective mechanisms designed to help
person cope with the stress or get away from it.
• For example, if you sense danger: Your heart rate increase,
BP rises, eyes dilates, blood sugar rises, bronchioles expand,
and blood flow shift from skin to skeletal muscles.

16. Functions of the Parasympathetic Nervous System
1. Rest and digest: maintains essential body functions; digestive
process and elimination of wastes.
2. Save energy.
3. Dilation of blood vessels in skin.
4. Decrease heart rate (bradycardia).
5. Increase secretion of digestive enzymes.
6. Constriction of smooth muscle of bronchi.
7. Increase in sweat glands.
8. Contraction of smooth muscles of urinary bladder.

17. The cholinergic neuron
• All preganglionic fibers of both sympathetic and
parasympathetic divisions.
• All parasympathetic postganglionic.
• Few sympathetic postganglionic fibers (sweat gland).
• All Somatic (non autonomic) fibers to skeletal muscle

18. The adrenergic neuron
• Most sympathetic postganglionic fibers release
norepinephrine; are noradrenergic or simply
adrenergic.
• Some peripheral sympathetic fibers release dopamine
(dopaminergic).
• The adrenal medulla, a modified sympathetic
ganglion, receives sympathetic preganglionic fibers
and releases epinephrine (~85%) and to a lesser
amount norepinephrine (15%) into the blood.

19. Receptor types
• Parasympathetic – cholinergic receptors:
– muscarinic (M1 to M5)
– and nicotinic receptors
• Sympathetic – adrenergic receptors:
– alpha (α1, α 2),
– beta (β1 to β 3),
– and dopamine (D1 to D5) receptors.

24. SYMPATHETIC AND PARASYMPATHETIC NS & EFFECTOR ORGANS

25. Thank you!