parasympathetic system

Question 1

function of the PNS

Answer 1

• rest and digest
• it increases digestion (and associated activities), slows heartbeat, constricts bronchioles in the lungs

Question 2

anatomy of the PNS

Answer 2

• pre-ganglionic nerves exit from top and bottom of the spinal cord
• they travel (Vagus = wanderer) to parasympathetic ganglia which tend to be located close to the target

Question 3

both the pre-ganglionic and the post ganglionic neurons are cholinergic meaning?

Answer 3

they release ACh

Question 4

what are the main tissue receptors in the PNS

Answer 4

muscarinic

Question 5

what is acetylcholine is made from?

Answer 5

choline and acetyl CoA

Question 6

in the synaptic cleft, what does the enzyme acetylcholinerase do?

Answer 6

rapidly break down ACh

Question 7

choline is transported back into where?

Answer 7

axon terminal

Question 8

what is this choline transported back into the axon terminal used to do?

Answer 8

make more ACh

Question 9

This synapse is more like a neuromuscular junction as it is a terminal synapse, autonomic synapses tend to be ‘en passant’ meaning?

Answer 9

(ie. in the middle of axons)

Question 10

What is the non-selective agonist for parasympathetic receptors?

Answer 10

Acetylcholine (acts on muscarinic and nicotinic agonists)

Question 11

examples of selective muscarinic receptor agonists + what do they generally do

Answer 11

Muscarine, Pilocarpine, Methacholine, Bethanechol
they mimic the effects of parasympathetic stimulation (e.g., increased secretions, GI motility)

Question 12

What is the effect of muscarinic antagonists? + examples of them

Answer 12

Block parasympathetic activity (e.g., dry mouth, dilated pupils, bronchodilation)
Atropine, Hyoscine Butylbromide, Ipratropium, Tiotropium

Question 13

what is a selective nicotinic agonist.

Answer 13

nicotine
stimulates nicotinic receptors in autonomic ganglia and CNS

Question 14

what is a selective nicotinic antagonist

Answer 14

hexamethonium
(Blocks nicotinic receptors in autonomic ganglia, reducing both sympathetic and parasympathetic output)

Question 15

examples of cholinergic agonists

Answer 15

acetylcholine
atropine
muscarine
hexamethonium

Question 16

Which neurotransmitter is released by the parasympathetic fibres

Answer 16

Acetylcholine (ACh)is the neurotransmitter released by parasympathetic nerve fibres.

Question 17

Name some targets in the body that are innervated by the parasympathetic nervous system and express the M3 muscarinic receptors for the following effects in these

Answer 17

• eye (pupil constriction)
• salivary glands (watery secretion)
• bladder (contraction of bladder and dilation of sphincter)
• airways (leads to bronchoconstriction and increased mucus secretion)

Question 18

Name a targets in the body that are innervated by the parasympathetic nervous system and express the M2 muscarinic receptors for the following effects in these

Answer 18

heart- leads to a decreased heart rate and force of contractions

Question 19

Name ONE (1) muscarinic agonist. Which tissues does it act on and for which conditions is it prescribed?

Answer 19

benthanchol chloride tablets (urivoid)
- tissues it acts on salivary glands, smooth muscle of urethra, GI tract
indicated for: dry mouth, promotes urination and GI motility

Question 20

Name ONE (1) muscarinic antagonist. Which tissues does it act on and for which conditions is it prescribed?

Answer 20

atropine sulfate
- acts on cardiac tissues to elevate heart rate
- acts on salivary gland to reduce secretions
so indicated for reduction of saliva and bradycardia