AUTONOMIC NERVOUS SYSTEM [ANS] DISCUSSION
Dr. Zahoor
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Q.1 What is Autonomic Nervous System (ANS)?
It’s the part of efferent division of PNS, but it is involuntary.
Q2. What are the divisions of ANS?
1. Sympathetic Autonomic Nervous System
2. Parasympathetic Autonomic Nervous System
Q3. Give the origin of Sympathetic ANS and Parasympathetic
ANS?
Sympathetic ANS thoracolumber outflow.:
• T1 - T12 and L1 – L2/L3
Parasympathetic ANS craniosacral outflow :
• cranial nerves: III, VII, IX, X
• sacral segments :S2,3,4.
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Q4. Draw diagram of Sympathetic and Parasympathetic ANS showing two neurons. [Preganglionic
and Postganglionic neuron]
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Q5.What is the difference between the length of Preganglionic and Postganglionic fiber in
parasympathetic and parasympathetic ANS?
sympathetic:
• Preganglionic fibers are shorter _ because they originate from the sympathetic cian:
• Postganglionic fibers are longer
parasympathetic :
• Preganglionic fibers are longer
• Postganglionic fibers are shorter – near effecter organQ6. What is the chemical transmitter at
Sympathetic ANS
Preganglionic Fibers Chemical Transmitter - acetylcholine
Postganglionic Fibers Chemical Transmitter – NE or NA
Parasympathetic ANS
Preganglionic Fibers Chemical Transmitter - acetylcholine
Postganglionic Fibers Chemical Transmitter - acetylcholine
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Q7. What is the action of sympathetic and parasympathetic ANS
at the following places?
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Q8. Name the adrenergic receptors where nor-epinephrine and epinephrine
acts?
Q9. What types of adrenergic receptors are present in the following?
i. Heart β1
ii. Bronchi β2
iii. Blood vessel α1
iv. Skeletal muscle blood vessel β2
v. GIT α2
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Q10. What is the chemical transmitter at postganglionic
sympathetic nerve ending supplying sweat glands?
acetylcholine
Q11. Acetylcholine released at postganglionic
parasympathetic nerve ending act on Muscarinic
receptors at target or Effector organ.
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Q12. What receptors are present at the ganglion in
Sympathetic ANS and Parasympathetic ANS?
Nicotinic receptors
Q13. What is Adrenal Medulla?
modified sympathetic ganglion. It does not give postganglionic fibers, but secretes
epinephrine and nor-epinephrine directly into the blood, therefore, it is called
Endocrine gland.
Q14. What hormones are released by adrenal medulla?
•
Adrenal medulla secretes
- 80% Epinephrine
- 20% Norepinephrine
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COMPARISON OF SYMPATHETIC &
PARASYMPATHETIC ANS
SYMPATHETIC
ANS
1.
2.
3.
4.
5.
6.
7.
PARASYMPATHETIC
ANS
Origin
Organization
Chemical Transmitters
Actions
Receptors
Dominance
Drugs acting on
adrenergic and
muscarinic receptors
Do the comparison yourself
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