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.
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
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
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