Block 9 Pharm Adrenergic W Exp Prt 1
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Which of the following molecular actions best explains the decrease in heart rate observed with norepinephrine infusion in a healthy subject?
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Activation of myocardial alpha-2 receptors
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Stimulation of aortic baroreceptors
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Activation of Nm receptors
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Blockade of myocardial muscarinic receptors
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Stimulation of chemoreceptors of aortic bodies
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This quiz assesses knowledge on adrenergic drugs, focusing on specific agents like Apraclonidine and Salmeterol, their mechanisms, and clinical applications. It is crucial for students and professionals in medicine and pharmacology.
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- 2.
Which of the following statements best explains the main mechanism of adrenergic actions of cocaine?
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Inhibition of monoamine oxidase A
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Blockade of alpha-2 receptors in sympathetic terminals
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Inhibition of norepinephrine reuptake into sympathetic nerve terminals
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Stimulation of epinephrine release from adrenal medulla
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Stimulation of norepinephrine release from sympathetic nerve terminals
Correct Answer
A. Inhibition of norepinephrine reuptake into sympathetic nerve terminalsExplanation
Answer: C
Cocaine is an indirect-acting adrenergic drug that block catecholamine uptake in both the central
and peripheral nervous system. Therefore the adrenergic actions of cocaine are due to the
increased availability of norepinephrine in the synaptic cleft.
A, B, D, E) All these listed mechanisms can increase the availability of norepinephrine or
epinephrine, but these are not mechanisms of action of cocaine.Rate this question:
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- 3.
This drug is a alpha-2 selective receptor agonist
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Albuterol
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Apraclonidine
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Cocaine
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Amphetamine
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Dobutamine
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Dopamine
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Epinephrine
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Ephedrine
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Methyldopa
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Norepinephrine
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Phenylephrine
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Salmeterol
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Tyramine
Correct Answer
A. ApraclonidineExplanation
Apraclonidine, is a sympathomimetic used in glaucoma therapy. It is an α2-adrenergic agonist and a weak ALPHA-1 ADRENERGIC RECEPTOR AGONIST.
Apraclonidine is administered at a concentration of 1% for the prevention and treatment of postsurgical intraocular pressure elevation and 0.5% for short-term adjunctive therapy in patients on maximally tolerated medical therapy who require additional redirection of intraocular pressure. One drop is usually added one hour prior to laser eye surgery and another drop is given after the procedure is complete.Rate this question:
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- 4.
Which of the following is the most common adverse effect of phenylephrine given locally into the eye for diagnostic purposes?
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Lacrimation
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Tachycardia
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Difficulty in far vision
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Photophobia
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Running nose
Correct Answer
A. PhotophobiaExplanation
Answer: D
Phenylephrine is an alpha-1 selective receptor agonist. When given locally in the conjunctival
sac it contracts the radial muscle of iris so causing mydriasis. The most common consequence of
mydriasis is photophobia since the pupil cannot constrict in response to bright light.
A) In most exocrine glands of the body (including lacrimal glands) activation of alpha-1 receptors
causes the formation of a concentrated secretion that contains enzymes and mucus. Moreover
the alpha receptor mediated vasoconstriction decreases the blood supply to the gland so the
actual amount of the lacrimal fluid is in fact decreased, not increased.
B) By increasing the blood pressure (both systolic and diastolic) phenylephrine usually triggers a
baroreceptor reflex that causes bradycardia, not tachycardia.
C) Alpha-1 receptor activation has no effect on the ciliary muscle and therefore does not
influence eye accommodation.
E) (see explanation A)Rate this question:
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- 5.
A 34-year-old woman was in the dentist office to have an endodontic therapy. Before starting the procedure the dentist injected near the tooth a solution of lidocaine plus epinephrine in order to provide local anesthesia. The epinephrine-induced increased duration of lidocaine effect was most likely mediated by the activation of which of the following receptors?
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Beta -1
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Beta -2
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Beta -3
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Alpha-1
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Alpha-2
Correct Answer
A. Alpha-1Explanation
Answer: D
Epinephrine is used quite often together with local anesthetics, in order to prolong the action of
the anesthetic. This increased duration is due to the epinephrine-induced vasoconstriction
(mediated by alpha-1 receptor activation) which localizes the anesthetic at the desired site, so
slowing down its systemic distribution.
A, B, C, E) (see explanation above)Rate this question:
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- 6.
This drug is a long-acting beta-2 selective receptor agonist
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Albuterol
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Apraclonidine
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Cocaine
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Amphetamine
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Dobutamine
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Dopamine
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Epinephrine
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Ephedrine
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Methyldopa
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Norepinephrine
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Phenylephrine
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Salmeterol
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Tyramine
Correct Answer
A. SalmeterolExplanation
Salmeterol is a long-acting beta-2 selective receptor agonist. This means that it specifically targets and activates beta-2 receptors in the body, leading to relaxation of the smooth muscles in the airways and bronchodilation. It is commonly used as a maintenance treatment for asthma and chronic obstructive pulmonary disease (COPD). By binding to the beta-2 receptors, salmeterol helps to open up the airways and improve breathing. Other drugs listed in the options do not possess the same mechanism of action as salmeterol.Rate this question:
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- 7.
The effects of epinephrine on the heart are most likely mediated by which of the following postreceptor mechanisms?
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Opening of ligand gated K+ channels
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Opening of ligand-gated Na+ channels
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Simulation of phospholipase C
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Stimulation of phospholipase A2
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Stimulation of adenylyl cyclase
Correct Answer
A. Stimulation of adenylyl cyclaseExplanation
Answer: E
Epinephrine effects on the heart are due to the activation of beta-1 and beta-2 receptors. The
postreceptor mechanism common to all beta receptor activation is the stimulation of adenylyl
cyclase which in turn increases the amount of cAMP in target tissues.
A) This postreceptor mechanism is triggered by the activation of M2 receptors.
B)This postreceptor mechanism is triggered by the activation of nicotinic receptors
C)This postreceptor mechanism is triggered by the activation alpha-1 and M3 receptors
D)This postreceptor mechanism is triggered by the activation of alpha-1 receptorsRate this question:
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- 8.
Which of the following is a pharmacological effect of isoproterenol?
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Stimulation of renin secretion
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Inhibition of insulin release
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Reflex bradycardia
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Release of inflammatory mediators from mast cells
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Stimulation of platelet aggregation
Correct Answer
A. Stimulation of renin secretionExplanation
Answer: A
Isoproterenol is a nonselective beta agonist, that is it activates all beta receptors. Activation of
beta-1 receptors in the juxtaglomerular cells of macula densa stimulates renin secretion.
C) Activation of beta-2 receptors in the vessels causes vasodilation. The decrease in blood
pressure triggers reflex tachycardia, not bradycardia.
D) Activation of beta-2 receptors on the surface of mast cells and basophils actually inhibits
degranulation of those cells.
E) This effects is mediated by the activation of alpha-2 receptors.Rate this question:
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- 9.
Which of the following is a pharmacological effect of albuterol on the respiratory system?
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Increased microvascular permeability
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Decreased bronchial secretions
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Release of histamine from mast cells
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Increased residual respiratory volume
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Increased mucociliary clearance
Correct Answer
A. Increased mucociliary clearanceExplanation
Answer: E
Albuterol is a beta-2 selective agonist. Activation of beta-2 receptors in the respiratory tract
increases mucociliary clearance so improving the flow of the coat of mucus toward the pharynx.
A, B, C) Beta-2 receptor agonists actually decrease microvascular permeability, increase
bronchial secretion and prevent the release of histamine from mast cells. All these actions are
useful in case of bronchospastic disorders.
D) Residual respiratory volume is not significantly affected in normal individuals but is actually
decreased in asthmatic patients.Rate this question:
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- 10.
This drug may cause a severe hypertensive crisis if taken together with a MAO inhibitor
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Albuterol
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Apraclonidine
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Cocaine
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Amphetamine
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Dobutamine
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Dopamine
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Epinephrine
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Ephedrine
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Methyldopa
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Norepinephrine
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Phenylephrine
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Salmeterol
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Tyramine
Correct Answer
A. TyramineExplanation
ATUALLY most of these drugs are contraindicated with MAOI's. But Dr B seems to think Tyramine is the most important.
SUPER IMPORTANT CLINICAL NOTE: (not on mini)
Tyramine occurs widely in plants and animals, and is metabolized by the enzyme monoamine oxidase. In foods, it is often produced by the decarboxylation of tyrosine during fermentation or decay. Foods containing considerable amounts of tyramine include meats that are potentially spoiled or pickled, aged, smoked, fermented, or marinated (some fish, poultry, and beef); most pork (except cured ham); chocolate; alcoholic beverages; and fermented foods, such as most cheeses (except ricotta, cottage cheese, cream cheese and neufchatel cheese), sour cream, yogurt, shrimp paste, soy sauce, soy bean condiments, teriyaki sauce, tofu, tempeh, miso soup, sauerkraut, broad (fava) beans, green bean pods, Italian flat (Romano) beans, snow peas, avocados, bananas, pineapple, eggplants, figs, red plums, raspberries, peanuts, Brazil nuts, coconuts, processed meat, yeast, and an array of cacti.Rate this question:
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- 11.
Which of the following is a common adverse effect of selective beta-2 receptor agonists in children?
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A-V block
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Restlessness
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Sleepiness
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Postural hypotension
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Ventricular tachycardia
Correct Answer
A. RestlessnessExplanation
Answer: B
Restlessness and anxiety are common adverse effect of beta-2 receptor agonists. They occur in
10-20% of children receiving inhalatory therapy. This points out that beta agonist are mainly
excitatory drugs for the CNS. In fact toxic doses usually cause convulsions.
A) Beta-2 receptor activation increases AV conduction, so AV block is quite unlikely.
C) Beta-2 receptor activation actually causes insomnia.
D) Hypotension can rarely occur with beta-2 agonists, but postural hypotension is unlikely since
the baroreceptor reflex can function normally.
E) Arrhythmias can occur with beta-2 agonists but ventricular tachycardia is exceedingly rare.Rate this question:
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- 12.
A 33-year-old man admitted to the hospital because of a car accident, started a blood transfusion. Few minutes later he complained of nausea and pruritus and developed dyspnea with audibly wheezing. His skin was mottled and cold, heart rate was 120 bpm and blood pressure fell to 80/ 40 mm Hg. An IV injection of epinephrine was given. Which of the following actions of the drug most likely contributed to its therapeutic efficacy in this patient?
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Increased glycogenolysis
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Beta-2 receptor mediated vasodilation
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Stimulation of platelet aggregation
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Inhibition of insulin secretion
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Inhibition of mast cell degranulation
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Stimulation of eicosanoid biosynthesis
Correct Answer
A. Inhibition of mast cell degranulationExplanation
The symptoms and signs of the patient suggest that he had an acute anaphylactic reaction which
sometimes occurs following a blood transfusion. One of the useful actions of epinephrine in this
disorder is the beta-2 receptor mediated inhibition of degranulation of mast cells which prevents
the release of histamine and other inflammatory mediators.
A, B, C, D, F) All these actions of epinephrine contribute little, if any, to the therapeutic efficacy
of the drug in this disorder.Rate this question:
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- 13.
This drug is an indirect acting adrenergic agent sometimes used as antihypertensive
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Albuterol
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Apraclonidine
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Cocaine
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Amphetamine
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Dobutamine
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Dopamine
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Epinephrine
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Ephedrine
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Methyldopa
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Norepinephrine
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Phenylephrine
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Salmeterol
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Tyramine
Correct Answer
A. MethyldopaExplanation
Methyldopa is an indirect acting adrenergic agent that is sometimes used as an antihypertensive. It works by being converted into methylnorepinephrine, which then acts as a false transmitter and reduces sympathetic outflow from the central nervous system. This ultimately leads to a decrease in blood pressure. Methyldopa is commonly used in the management of hypertension during pregnancy.Rate this question:
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- 14.
Which of the following autonomic drugs given IV to healthy subjects can cause an increase in cardiac contractility, a slight increase in heart rate and no major changes or a decrease in systemic vascular resistance?
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Phenylephrine
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Norepinephrine
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Isoproterenol
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Epinephrine
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Dobutamine
Correct Answer
A. DobutamineExplanation
Answer: E
Dobutamine is a selective beta agonist that activates mainly beta-1 receptors. This would cause
an increase of all the parameters of heart activity but, for unknown reasons, frequency and
automaticity are increased only slightly. Affinity of dobutamine for alpha-1 and beta-2 receptors
is slight (high doses are needed) and, moreover, the consequences of this activation on the
vessel caliber can balance each other. This can explain why there are no major changes or a
decrease in SVR (when the beta-2 mediated vasodilation overrides the alpha-1 mediated
vasoconstriction).
A, B, C, D) All these listed drugs cause substantial changes in heart rate and systemic vascular
resistance..Rate this question:
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- 15.
A 57-year-old homeless alcoholic man was brought to the hospital by the police who found him lying on a sidewalk. Physical examination showed evident signs of alcohol withdrawal and a therapy was started which included clonidine. Which of the following phrases best explains the most likely mechanism of action of the drug in this patient?
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Decreased central sympathetic outflow
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Activation of peripheral alpha-1 receptors
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Decreased central parasympathetic outflow
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Activation of peripheral alpha-2 receptors
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Blockade of alpha receptors on tractus solitarius
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Blockade of alpha receptors on locus ceruleus
Correct Answer
A. Decreased central sympathetic outflowExplanation
Answer: A
Clonidine is often used to decrease the symptoms of sympathetic activation which are prominent
during withdrawal from many sedative drugs including alcohol and opioids. Many of those
symptoms are due to an increased firing from locus ceruleus, a brain nucleus with a very high
concentration of alpha receptors. By activation alpha-2 presynaptic receptors clonidine
decreases the central sympathetic outflow so antagonizing the increased firing from locus
ceruleus.
B, D) Clonidine activates peripheral adrenergic receptors only when very high doses are given.
C) Actually clonidine increases central parasympathetic outflow.
E, F) Clonidine activates, not blocks, these receptors.Rate this question:
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Current Version
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Mar 20, 2023Quiz Edited by
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Jun 03, 2012Quiz Created by
Chachelly
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