Chapter 4 Flashcards
act on receptors stimulated
by norepinephrine or epinephrine.
a. adrenergic drug
b. cholinergic drugs
a. adrenergic drug
act on receptors activated by acetylcholine (ACh)
a. adrenergic drug
b. cholinergic drugs
b. cholinergic drugs
Choline is transported from the
extracellular fluid into the cytoplasm of the cholinergic neuron by
an energy-dependent carrier system that cotransports sodium and
can be inhibited by the drug
a. echothiophate
b.hemicholinium
b.hemicholinium
Choline has
a quaternary _____and carries a permanent positive charge
and, thus, cannot diffuse through the membran
Choline has
a quaternary nitrogen and carries a permanent positive charge
and, thus, cannot diffuse through the membran
____is the rate-limiting step in ACh synthes
The uptake of
choline is the rate-limiting step in ACh synthes
______catalyzes the reaction of choline with acetyl coenzyme
A (CoA) to form ACh (an ester) in the cytosol.
. Choline acetyl-
transferase catalyzes the reaction of choline with acetyl coenzyme
A (CoA) to form ACh (an ester) in the cytosol.
ACh is packaged and
stored into presynaptic vesicles by an active transport process.
The mature vesicle contains not only ACh but also _____and _____
ACh is packaged and
stored into presynaptic vesicles by an active transport process.
The mature vesicle contains not only ACh but also adenosine
triphosphate (ATP) and proteoglycan
at synthesis and release of acethylcholine…When an action potential propagated
by voltage-sensitive sodium channels arrives at a nerve ending,
voltage-sensitive _____ channels on the presynaptic membrane
open, causing an increase in the concentration of intracellular
____.
calcium
at synthesis and release of acethylcholine… what will happen if their is an increase in intracellular calcium
Elevated calcium levels promote the fusion of synaptic
vesicles with the cell membrane and the release of contents into
the synaptic space.
Acethylcholines release is blocked by
a. botulinum toxin
b. Spider venom
a. botulinum toxin
this causes
release of acetylcholine.
a. botulinum toxin
b. Spider venom
b. Spider venom
Acetylcholine is rapidly
hydrolyzed by ___ in the
synaptic cleft.
a.acetyl-
cholinesterase
b. Choline acetyltransferase
a.acetyl-
cholinesterase
catalyzes the synthesis of
acetylcholine from choline
and acetyi-CoA.
a.acetyl-
cholinesterase
b. Choline acetyltransferase
b. Choline acetyltransferase
Choline is taken
up by the neuron.
This transport is
inhibited by
a. hemicholinium
b. echothiophate
a. hemicholinium
what are the two families of cholinoceptors
muscarinic and nicotinic
receptors,
belong to the class of G-protein–coupled
receptors (metabotropic receptors).
a. nicotinic receptor
b. muscarinic receptor
b. muscarinic receptor
an alkaloid in certain poi-
sonous mushrooms.
muscarine.
muscarinic receptor also recognize muscarine
the muscarinic receptors show only
a weak affinity for
a. muscarine
b. acethylcholine
c. nicotine
c. nicotine
alkaloid found in tobacco and other
plants
a. muscarine
b. acethylcholine
c. nicotine
c. nicotine
These receptors are found on
the autonomic effector organs, such as the heart, smooth muscle,
brain, and exocrine glands
a. muscarinic receptor
b. nicotinic receptor
a. muscarinic receptor
what subclass of muscaribic receptor are also found on gastric parietal cells,
a. M1
b. M 2
c. M3
a. M1
what subclass of muscarinic receptors on cardiac cells and smooth muscle
a. M1
b. M 2
c. M3
b. M 2
what subclass of muscarinic receptor receptors
on the bladder, exocrine glands, and smooth muscle.
a. M1
b. M 2
c. M3
c. M 3
what muscarinic receptor subclass are activated, the receptor undergoes a conformational
change and interacts with a G-protein that activates phospholi-
pase C. This ultimately leads to production of second messen-
gers inositol-1 ,4,5-trisphosphate (IP3) and diacylglycerol (DAG).
IP3 causes an increase in intracellular Ca2+. Calcium can then
interact to stimulate or inhibit enzymes or to cause hyperpolar-
ization, secretion, or contraction. DAG activates protein kinase C,
an enzyme that phosphorylates numerous proteins within the cell.
a. M1
b. M 2
c. M3
a. M1 or c. M3
what muscarinic receptor subtype on the cardiac muscle
stimulates a G-protein that inhibits adenylyl cyclase and increases
K+ conductance. The heart responds with a decrease in rate and
force of contraction.
a. M1
b. M 2
c. M3
b. M2
when M1 or M3
receptors are activated, the receptor undergoes a conformational
change and interacts with a G-protein that activates ___. This ultimately leads to production of second messen-
gers ___ and ____.
_____ causes an increase in intracellular Ca2+. Calcium can then
interact to stimulate or inhibit enzymes or to cause hyperpolar-
ization, secretion, or contraction. ____ activates protein kinase C,
an enzyme that phosphorylates numerous proteins within the cell.
when M1 or M3
receptors are activated, the receptor undergoes a conformational
change and interacts with a G-protein that activates ___. This ultimately leads to production of second messen-
gers inositol-1 ,4,5-trisphosphate (IP3) and diacylglycerol (DAG).
IP3 causes an increase in intracellular Ca2+. Calcium can then
interact to stimulate or inhibit enzymes or to cause hyperpolar-
ization, secretion, or contraction. DAG activates protein kinase C,
an enzyme that phosphorylates numerous proteins within the cell.
For example, when M1 or M3
receptors are activated, the receptor undergoes a conformational
change and interacts with a G-protein that activates
phospholi-
pase C
activation ofphospholipase C will lead to formation of what secondary messenger?
inositol-1 ,4,5-trisphosphate (IP3) and diacylglycerol (DAG).
what secondary messenger increase intracellular calcium?
a.inositol-1 ,4,5-trisphosphate (IP3)
b. diacylglycerol (DAG).
a.inositol-1 ,4,5-trisphosphate (IP3)
can then
interact to stimulate or inhibit enzymes or to cause hyperpolar-
ization, secretion, or contraction.
a. potassium
b. calcium
b. calcium
what will diacylglycerol (DAG) activate
protein kinase C,
an enzyme that phosphorylates numerous proteins within the cell.
protein kinase C,
what will be the respondactivation of the M2 subtype on the cardiac muscle
stimulates a G-protein that inhibits adenylyl cyclase and increases
K+ conductance
The heart responds with a decrease in rate and
force of contraction.
is a nonselective muscarinic
agonist used to treat xerostomia and glaucoma.
a. pilocarpine
b. cevimeline
a. pilocarpine
also recognize nicotine
but show only a weak affinity for muscarine
a. muscarinic receptor
b. nicotinic receptor
b. nicotinic receptor
it functions as a
ligand-gated ion channel (ionotropic receptor)
a. muscarinic receptor
b. nicotinic recrptor
b. nicotinic recrptor
Binding of two ACh
molecules elicits a conformational change that allows the entry of
sodium ions, resulting in the ___ of the effector cell.
a. repolarization
b. depolarization
b.depolarization
notes : Nicotine
at low concentration stimulates the receptor, whereas nicotine at high
concentration blocks the receptor
receptors are located in
the CNS, the adrenal medulla, autonomic ganglia, and the neuro-
muscular junction (NMJ) in skeletal muscles
a. muscarinic receptor
b. nicotinic receptor
b. nicotinic receptor
the gan-
glionic receptors are selectively blocked by
a. mecamylamine,
b. atracurium.
a. mecamylamine
nicotinic NMJ (neuro-muscular junction) receptors are specifically blocked by a. mecamylamine,
b. atracurium.
b. atracurium.
Cholinergic agonists mimic the effects of ACh by binding directly to
cholinoceptors (muscarinic or nicotinic). These agents may be broadly
classified into two groups:
1) choline esters, which include endogenous
ACh and synthetic esters of choline, such as carbachol and bethanechol,
and 2) naturally occurring alkaloids, such as nicotine and pilocarpine
which include endogenous
ACh and synthetic esters of choline
a. choline esters
b. naturally occurring alkaloids
a. choline esters
carbachol
a. choline esters
b. naturally occurring alkaloids
a. choline esters
bethanechol
a. choline esters
b. naturally occurring alkaloids
a. choline esters
nicotine
a. choline esters
b. naturally occurring alkaloids
b. naturally occurring alkaloids
pilocarpine
a. choline esters
b. naturally occurring alkaloids
b. naturally occurring alkaloids
a quaternary ammonium
compound that cannot penetrate membranes.
a. acetylcholine
b.betanechol
c. carbachol
a. acetylcholine
note:it lacks therapeutic importance because of its
multiplicity of actions (leading to diffuse effects) and its rapid inactiva-
tion by the cholinesterases
ACh has both muscarinic and nicotinic
activity.
a. acetylcholine
b.betanechol
c. carbachol
a. acetylcholine
Decrease in heart rate and cardiac output
a. acetylcholine
b.betanechol
c. carbachol
a. acetylcholine
Decrease in blood pressure
a. acetylcholine
b.betanechol
c. carbachol
a. acetylcholine
note:Injection of ACh causes vasodila-
tion and lowering of blood pressure by an indirect mechanism of
action. ACh activates M3 receptors found on endothelial cells lining
the smooth muscles of blood vessels. This results in the production of nitric oxide from arginine. Nitric oxide then diffuses to vascular
smooth muscle cells to stimulate protein kinase G production,
leading to hyperpolarization and smooth muscle relaxation via
phosphodiesterase-3 inhibition. In the absence of administered
cholinergic agents, the vascular cholinergic receptors have no
known function, because ACh is never released into the blood in
significant quantities. Atropine blocks these muscarinic receptors
and prevents ACh from producing vasodilation.
ACh activates M3 receptors found on endothelial cells lining
the smooth muscles of blood vessels. This results in the production
nitric oxide from arginine
At ACh…Nitric oxide then diffuses to vascular
smooth muscle cells to stimulate
protein kinase G production
the stimulation of protein kinase G produce
leading to hyperpolarization and smooth muscle relaxation via
phosphodiesterase-3 inhibition.
what is the effect of acethylcholine in our grastrointestinal tract
In the gastrointestinal {GI) tract, acetylcholine
increases salivary secretion, increases gastric acid secretion,
and stimulates intestinal secretions and motility.
note:It also enhances
bronchiolar secretions and causes bronchoconstriction.
blocks these muscarinic receptors
and prevents ACh from producing vasodilation.
a. Atropine
b. Metacholine
a. Atropine
a direct-acting cholinergic agonist, is used to assist
in the diagnosis of asthma due to its bronchoconstricting prop-
erties.
a. Atropine
b. Metacholine
b. Metacholine
note:In the genitourinary tract, ACh increases the tone of the
detrusor muscle, causing urination. In the eye, ACh is involved
in stimulation of ciliary muscle contraction for near vision and in
the constriction of the pupillae sphincter muscle, causing miosis
{marked constriction of the pupil). ACh {1% solution) is instilled
into the anterior chamber of the eye to produce miosis during oph-
thalmic surgery.
is an unsubstituted carbamoyl ester,
structurally related to ACh.
a. acetylcholine
b.betanechol
c. carbachol
b.betanechol
It is not hydrolyzed by AChE
due to the esterification of carbamic acid, although it is inactivated
through hydrolysis by other esterases.
a. acetylcholine
b.betanechol
c. carbachol
b.betanechol
bethanechol is inactivated by
a. esterification
b. hydrolysis
b. hydrolysis
it is inactivated
through hydrolysis by other esterases.
why betanechol lacks nicotiic actions?
a. because of its carbamoyl group
b. because of is an ester
c. because of its methyl group
c. because of its methyl group
but does have strong muscarinic
activity.
where is the major action of bethanechol?
Its major actions are on the smooth musculature of the bladder and Gl tract.
How long is the diration of action of bethanechol?
1 hour duration of action
directly stimulates muscarinic receptors,
causing increased intestinal motility and tone. It also stimulates the
detrusor muscle of the bladder, whereas the trigone and sphincter
muscles are relaxed. These effects stimulate urination.
a. acetylcholine
b.betanechol
c. carbachol
b.betanechol
is used to
stimulate the atonic bladder, particularly in postpartum or postoperative, nonobstructive urinary retention.
a. acetylcholine
b.betanechol
c. carbachol
b.betanechol