The document discusses the organization and function of the autonomic nervous system (ANS). The ANS regulates organs automatically and unconsciously. It has two divisions - the sympathetic and parasympathetic nervous systems. The sympathetic system is active during fight or flight responses while the parasympathetic system acts during rest and digestion. Most organs receive input from both divisions, allowing for cooperative or opposing effects. The ANS maintains homeostasis through its control of various body systems.

1. Topic : organization of ANS , its subdivision ,
and innervations.
 Zulcaif Ahmad
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2. AUTONOMIC NERVOUS SYSTEM
Organization of ANS

3. Autonomic nervous system

4. Autonomic nervous system
 ANS is to a large extent responsible for
automatically and subconsciously regulating
the
cardiovascular, renal, gastrointestinal, therm
oregulatory, and other systems.
 The ANS affects heart
rate, digestion, respiratory
rate, salivation, perspiration, pupillary
dilation , micturition and sexual arousal

5. Autonomic nervous system
 The ANS is located in the medulla oblongata.
 The ANS helps in homeostasis.
 The autonomic nervous system along with
endocrine system coordinates the regulation

6. Autonomic nervous system
 The autonomic nervous system (ANS) is to a
large extent responsible for automatically
and subconsciously regulating the
cardiovascular, renal, gastrointestinal,
thermoregulatory, and other systems
 The hypothalamus is the main integration center
of ANS activity.

7. Subdivisions
The nervous system is divided into two major
types:
• CNS
• PNS

8. Subdivisions
 CNS:
 Brain
(forebrain , midbrain , hind brain )
 Spinal cord
(white matter , grey matter)

9. Subdivisions

10. Subdivisions
 PNS:
• Sensory neurons
• Motor neurons

11. Subdivisions
 Motor neurons
• Somatic nervous system (voluntary)
• Autonomic nervous system(involuntary)

12. Subdivisions

13. Cholinergic Receptors
 The two types of receptors that bind ACh are
nicotinic and muscarinic .
 These are named after drugs that bind to
them and mimic ACh effects

14. Nicotinic Receptors
 Nicotinic receptors are found on:
Motor end plates (somatic targets)
All ganglionic neurons of both sympathetic
and parasympathetic divisions
The hormone-producing cells of the adrenal
medulla
The effect of ACh binding to nicotinic receptors
is always stimulatory

15. Muscarinic Receptors
 Muscarinic receptors occur on all effector
cells stimulated by postganglionic cholinergic
fibers
 The effect of ACh binding:
 Can be either inhibitory or excitatory
 Depends on the receptor type of the target organ

16. Adrenergic Receptors
 The two types of adrenergic receptors are
alpha and beta
 Each type has two or three subclasses
( 1, 2, 1, 2 , 3)
 Effects of NE binding to:
 receptors is generally stimulatory
 receptors is generally inhibitory
 A notable exception – NE binding to
receptors of the heart is stimulatory

17. Subdivisions
 ANS:
• Sympathetic nervous system
• Parasympathetic nervous system

18. Subdivisions
Sympathetic nervous system:
Sympathetic “Fight or flight” “E” division
Exercise, excitement, emergency, and
embarrassment .

19. Subdivisions
Parasympathetic nervous system:
Parasympathetic “Rest and digest” “D” division
Digestion, defecation, and diuresis

20. Innervations:
 Autonomic nerve fibers innervate cardiac
muscle, smooth muscle, and glands.
 A muscle or gland innervated by autonomic
fibers is called an effector organ.

21. Innervations:
 AUTONOMIC INNERVATION Heart: The
heart is well supplied by SNS and PNS. These
nerves affect cardiac pumping is 3 ways - By
changing the rate By changing the strength
of contraction . Modulating coronary blood
flow. The PNS cardiac vagal fibres approaches
the stellate ganglion and then join the
efferent cardiac SNS fibres.

22. Innervations:
 Lungs : Lungs are innervated by both SNS
and PNS. Postganglionic SNS fibres from
upper thoracic ganglia (stellate) pass to the
lungs to innervate the smooth muscles of the
bronchi and pulmonary blood vessels. PNS
innervation of these structures is from the
vagus nerve

23. Dual Innervation:
 Most of viscera receive nerve fibers from both
parasympathetic and sympathetic divisions
 Both divisions do not normally innervate an
organ equally

24. Dual Innervation:
 Antagonistic effects
 oppose each other
 exerted through dual innervation of same effector
 heart rate decreases (parasympathetic)
 heart rate increases (sympathetic)
 exerted because each division innervates different
cells
 pupillary dilator muscle (sympathetic) dilates pupil
 constrictor pupillae (parasympathetic) constricts
pupil

25. Dual Innervation:
 Cooperative effects seen when 2 divisions act on
different effectors to produce a unified effect
 parasympathetics increase salivary serous cell
secretion
 sympathetics increase salivary mucous cell secretion
ANS cooperation is best seen in control of the
external genitalia
 Parasympathetic fibers cause vasodilation and are
responsible for erection of the penis and clitoris
 Sympathetic fibers cause ejaculation of semen in
males and reflex peristalsis in females

26. Dual Innervation of the Iris:

27. Without Dual Innervation:
 Some effectors receive only sympathetic
 adrenal medulla, arrector pili muscles, sweat glands
and many blood vessels
 Sympathetic tone
 a baseline firing frequency
 vasomotor tone provides partial constriction
 increase in firing frequency = vasoconstriction
 decrease in firing frequency = vasodilation
 can shift blood flow from one organ to another as needed
 sympathetic stimulation increases blood to skeletal and
cardiac muscles -- reduced blood to skin

28. Sympathetic and Vasomotor
Tone:
 Sympathetic division
prioritizes blood vessels
to skeletal muscles and
heart in times of
emergency.

29. Sympathetic and Vasomotor
Tone:
 Blood vessels to skin vasoconstrict to
minimize bleeding if injury occurs during
stress or exercise.

30. references
 Page 37 in: Costanzo, Linda S. (2007). Physiology.
Hagerstwon, MD: Lippincott Williams & Wilkins. ISBN 0-7817-
7311-3.
 Loppincott’s illustrated reviews (pharmacology)
 http://www.neurophysiology.ws/autonomicns.htm
 http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/PN
S.html
 ^ Rang, H. P. (2003). Pharmacology. Edinburgh: Churchill
Livingstone. ISBN 0-443-07145-4. Page 270.
 http://www.ld99.com/reference/old/text/2878909-413.html
 http://www.pc.maricopa.edu/Biology/pfinkenstadt/BIO201/20
1LessonBuilder/UnitFour/ANS/index.html

31. references
 Essentials of medical physiology by jaypee ,
5th edition.