PMCOL 343- ANS III EXAM
STUDY GUIDE
Where are muscarinic receptors found; what type of effect do they have when activated
- Answer Found in smooth muscle, cardiac muscle, and glands; once activated they
have parasympathomimetic effects
Where are nicotinic receptors found; what type of receptor are they - Answer Found in
autonomic ganglia and in skeletal muscle; are ionotropic receptors
Describe why ACh is poorly absorbed from the GIT (2) - Answer 1. ACh is broken down
by acetylcholinesterase, which is present in the GIT
2. ACh is a charged molecule, making it hard to pass through cell membranes
There are three heavily used cholinergic agonists; what are these three - Answer
Carbachol, bethanechol, and methacholine
What type of receptors does carbachol act on - Answer Carbachol is a synthetic
cholinergic agent that acts on both muscarinic and nicotinic receptors
What type of receptors does bethanechol act on - Answer Muscarinic receptors (low
nicotinic activity)
Describe the therapeutic use of bethanechol being only able to affect muscarinic
receptors - Answer Makes it more suitable for stimulating smooth muscle in the GI and
urinary systems, while minimizing effects on skeletal muscle
Methacholine can be used to diagnosis asthma; describe the process of diagnosing
asthma using methacholine - Answer Patient is given methacholine; if the airways are
hyperreactive (in asthma), then even low concentrations of methacholine can trigger
bronchoconstriction
Between carbachol, bethanechol, and methacholine, which are not easily hydrolyzed by
enzyme acetylcholinesterase; what effect does this have on the drug effects - Answer
Carbachol and bethanecol are not easily hydrolyzed by acetylcholinesterase; this
makes its effects more long lasting
There are three heavily used muscarinic agonists; what are these three - Answer
Muscarine, oxotremorine, and pilocarpine
What occurs when muscarinic receptors on intact endothelium are activated by an
agonist - Answer Cause the blood vessels to dilate
, When M3 receptors on endothelial cells are activated, they release nitric oxide that
diffuses into the vascular smooth muscle cells; what does this NO in the smooth muscle
cell promote - Answer Promotes the conversion of soluble guanylyl cyclase into cyclic
GMP, which promotes blood vessel dilation (muscle relaxation)
What occurs in the heart when muscarinic receptors are activated by an agonist -
Answer Parasympathomimetic effects; slowed heart rate, decreased force / rate of
contraction
What does mAChR activation in the respiratory system promote - Answer Promotes
bronchoconstriction (harder to breathe) and increased mucus secretion (harder to
breathe)
What does mAChR activation in the GIT promote - Answer Promotes GIT motility
(peristalsis) and increased secretion of saliva and stomach acid
What does mAChR activation in the bladder promote - Answer Contraction of the
detrusor muscle (allows for voiding)
Nicotine is an agonist for nACh receptors; what does activation of nAChR by nicotine in
the CNS lead to - Answer Increased alertness, enhanced mood, improved
concentration, and dopamine release (stimulatory effects)
How can extremely high doses of nicotine cause a coma - Answer High doses of nicotine
can lead to respiratory depression, resulting in a lack of oxygen in the bloodstream,
which could lead to a coma
Describe how nicotine can be used as an insecticide - Answer Extreme activation of
nAChRs in the CNS can lead to overstimulation of nerve cells, resulting in paralysis and
ultimately death
How can activation of nAChRs stimulate both sympathetic and parasympathetic
branches of the ANS - Answer nAChRs are located on both sympathetic and
parasympathetic postganglionic nerves
What is nicotine's cardiovascular effects - Answer Increased blood pressure, increased
cardiac stimulation (sympathomimetic)
What is nicotine's GIT effects - Answer Increased secretion and motility
(parasympathetic)
What is nicotine's skeletal muscle effects - Answer Depolarization and excitation of
skeletal muscle (can vary from disorganized to a strong contraction of the whole
muscle)
What is the mechanism of action for anticholinesterases; what effect does this have -
Answer Inhibit the action of acetylcholinesterase, resulting in increased stimulation of
mAChRs and nAChRs
STUDY GUIDE
Where are muscarinic receptors found; what type of effect do they have when activated
- Answer Found in smooth muscle, cardiac muscle, and glands; once activated they
have parasympathomimetic effects
Where are nicotinic receptors found; what type of receptor are they - Answer Found in
autonomic ganglia and in skeletal muscle; are ionotropic receptors
Describe why ACh is poorly absorbed from the GIT (2) - Answer 1. ACh is broken down
by acetylcholinesterase, which is present in the GIT
2. ACh is a charged molecule, making it hard to pass through cell membranes
There are three heavily used cholinergic agonists; what are these three - Answer
Carbachol, bethanechol, and methacholine
What type of receptors does carbachol act on - Answer Carbachol is a synthetic
cholinergic agent that acts on both muscarinic and nicotinic receptors
What type of receptors does bethanechol act on - Answer Muscarinic receptors (low
nicotinic activity)
Describe the therapeutic use of bethanechol being only able to affect muscarinic
receptors - Answer Makes it more suitable for stimulating smooth muscle in the GI and
urinary systems, while minimizing effects on skeletal muscle
Methacholine can be used to diagnosis asthma; describe the process of diagnosing
asthma using methacholine - Answer Patient is given methacholine; if the airways are
hyperreactive (in asthma), then even low concentrations of methacholine can trigger
bronchoconstriction
Between carbachol, bethanechol, and methacholine, which are not easily hydrolyzed by
enzyme acetylcholinesterase; what effect does this have on the drug effects - Answer
Carbachol and bethanecol are not easily hydrolyzed by acetylcholinesterase; this
makes its effects more long lasting
There are three heavily used muscarinic agonists; what are these three - Answer
Muscarine, oxotremorine, and pilocarpine
What occurs when muscarinic receptors on intact endothelium are activated by an
agonist - Answer Cause the blood vessels to dilate
, When M3 receptors on endothelial cells are activated, they release nitric oxide that
diffuses into the vascular smooth muscle cells; what does this NO in the smooth muscle
cell promote - Answer Promotes the conversion of soluble guanylyl cyclase into cyclic
GMP, which promotes blood vessel dilation (muscle relaxation)
What occurs in the heart when muscarinic receptors are activated by an agonist -
Answer Parasympathomimetic effects; slowed heart rate, decreased force / rate of
contraction
What does mAChR activation in the respiratory system promote - Answer Promotes
bronchoconstriction (harder to breathe) and increased mucus secretion (harder to
breathe)
What does mAChR activation in the GIT promote - Answer Promotes GIT motility
(peristalsis) and increased secretion of saliva and stomach acid
What does mAChR activation in the bladder promote - Answer Contraction of the
detrusor muscle (allows for voiding)
Nicotine is an agonist for nACh receptors; what does activation of nAChR by nicotine in
the CNS lead to - Answer Increased alertness, enhanced mood, improved
concentration, and dopamine release (stimulatory effects)
How can extremely high doses of nicotine cause a coma - Answer High doses of nicotine
can lead to respiratory depression, resulting in a lack of oxygen in the bloodstream,
which could lead to a coma
Describe how nicotine can be used as an insecticide - Answer Extreme activation of
nAChRs in the CNS can lead to overstimulation of nerve cells, resulting in paralysis and
ultimately death
How can activation of nAChRs stimulate both sympathetic and parasympathetic
branches of the ANS - Answer nAChRs are located on both sympathetic and
parasympathetic postganglionic nerves
What is nicotine's cardiovascular effects - Answer Increased blood pressure, increased
cardiac stimulation (sympathomimetic)
What is nicotine's GIT effects - Answer Increased secretion and motility
(parasympathetic)
What is nicotine's skeletal muscle effects - Answer Depolarization and excitation of
skeletal muscle (can vary from disorganized to a strong contraction of the whole
muscle)
What is the mechanism of action for anticholinesterases; what effect does this have -
Answer Inhibit the action of acetylcholinesterase, resulting in increased stimulation of
mAChRs and nAChRs
