Midterm Sample Exam Flashcards
A 3-year-old child has been admitted to the emergency department having swallowed the contents of 2 bottles of a nasal decongestant. The active ingredient of the medication is a potent, selective α-adrenoceptor agonist drug. Which of the following is a sign of α-receptor activation that may occur in this patient?
(A) Bronchodilation
(B) Cardiac acceleration (tachycardia)
(C) Pupillary dilation (mydriasis)
(D) Renin release from the kidneys
(E) Vasodilation of the blood vessels of the skin
Mydriasis can be caused by contraction of the radial fibers of the iris; these smooth muscle cells have α receptors. All the other listed responses are mediated by β adrenoceptors (Table 6–4). The answer is C.
Mr Green is a 60-year-old man with poorly controlled hypertension of 170/110 mm Hg. He is to receive minoxidil. Minoxidil is a powerful arteriolar vasodilator that does not act on autonomic receptors. Which of the following effects will be observed if no other drugs are used?
(A) Tachycardia and increased cardiac contractility
(B) Tachycardia and decreased cardiac output
(C) Decreased mean arterial pressure and decreased cardiac
contractility
(D) Decreased mean arterial pressure and increased salt and
water excretion by the kidney
(E) No change in mean arterial pressure and decreased car-
diac contractility
Because of the compensatory responses, a drug that directly decreases blood pressure through a decrease in peripheral vascular resistance will cause a reflex increase in sympathetic outflow, an increase in renin release, and a decrease in para- sympathetic outflow. As a result, heart rate and cardiac force will increase. In addition, salt and water retention will occur. The answer is A.
Full activation of the parasympathetic nervous system is likely to produce which of the following effects?
(A) Bronchodilation
(B) Decreased intestinal motility
(C) Increased thermoregulatory sweating
(D) Increased pupillary constrictor tone (miosis) (E) Increased heart rate (tachycardia)
Parasympathetic discharge causes bronchial and intestinal smooth muscle contraction and bradycardia. Thermoregula- tory (eccrine) sweat glands are innervated by sympathetic cholinergic fibers, not parasympathetic. The answer is D.
Nicotinic receptor sites do not include which one of the fol- lowing sites?
(A) Bronchial smooth muscle
(B) Adrenal medullary cells
(C) Parasympathetic ganglia
(D) Skeletal muscle end plates
(E) Sympathetic ganglia
Both types of ganglia and the skeletal muscle neuromus- cular junction have nicotinic cholinoceptors, as does the adrenal medulla (a modified form of sympathetic ganglionic neuron tissue). Bronchial smooth muscle contains mus- carinic cholinoceptors and noncholinergic receptors. The answer is A.
Several children at a summer camp were hospitalized with symptoms thought to be due to ingestion of food contain- ing botulinum toxin. Which one of the following signs or symptoms is consistent with the diagnosis of botulinum poisoning?
(A) Bronchospasm
(B) Cycloplegia
(C) Diarrhea
(D) Skeletal muscle spasms
(E) Hyperventilation
Botulinum toxin impairs all types of cholinergic transmis- sion, including transmission at ganglionic synapses and somatic motor nerve endings. Botulinum toxin prevents discharge of vesicular transmitter content from cholinergic nerve endings. All of the signs listed except cycloplegia indicate increased muscle contraction; cycloplegia (paraly- sis of accommodation) results in blurred near vision. The answer is B.
Which one of the following is the primary neurotransmitter agent normally released in the sinoatrial node of the heart in response to a blood pressure increase?
(A) Acetylcholine
(B) Dopamine
(C) Epinephrine
(D) Glutamate
(E) Norepinephrine
Whenbloodpressureincreases,theparasympatheticsystem is activated and heart rate decreases. Acetylcholine is the transmitter at parasympathetic nerve endings innervating the sinus node (nerve endings of the vagus nerve). The answer is A.
A 27-year old compulsive drug user injected a drug he thought was methamphetamine, but he has not developed any signs of methamphetamine action. He has been admitted to the emergency department and antimuscarinic drug over- dose is suspected. Probable signs of atropine overdose include which one of the following?
(A) Gastrointestinal smooth muscle cramping (B) Increased heart rate
(C) Increased gastric secretion
(D) Pupillary constriction
(E) Urinary frequency
Tachycardia is a characteristic atropine overdose effect. Brady- cardia is sometimes observed after small doses. None of the other choices are typical of atropine or methamphetamine overdose. The answer is B.
Which of the following is the most dangerous effect of bel- ladonna alkaloids in infants and toddlers?
(A) Dehydration
(B) Hallucinations
(C) Hypertension
(D) Hyperthermia
(E) Intraventricular heart block
Choices B, D, and E are all possible effects of the atropine group. In infants, however, the most dangerous effect is hyperthermia. Deaths with body temperatures in excess of 42°C have occurred after the use of atropine-containing eye drops in children. The answer is D.
Which one of the following can be blocked by atropine?
(A) Decreased blood pressure caused by hexamethonium (B) Increased blood pressure caused by nicotine
(C) Increased skeletal muscle strength caused by neostigmine (D) Tachycardia caused by exercise
(E) Sweating caused by exercise
Atropine blocks muscarinic receptors and inhibits parasym- pathomimetic effects. Nicotine can induce both parasym- pathomimetic and sympathomimetic effects by virtue of its ganglion-stimulating action. Hypertension and exercise-induced tachycardia reflect sympathetic discharge with norepinephrine release and therefore would not be blocked by atropine. Exercise- induced sweating is another sympathomimetic response, but it is mediated by acetylcholine released from sympathetic nerve fibers at eccrine sweat glands. The answer is E.
Two new synthetic drugs (X and Y) are to be studied for their cardiovascular effects. The drugs are given to three anesthetized animals while the blood pressure is recorded. The first animal has received no pretreatment (control), the second has received an effective dose of a long-acting ganglion blocker, and the third has received an effective dose of a long-acting muscarinic antagonist.
- Drug X caused a 50 mm Hg rise in mean blood pressure in the control animal, no blood pressure change in the ganglion- blocked animal, and a 75 mm mean blood pressure rise in the atropine-pretreated animal. Drug X is probably a drug similar to
(A) Acetylcholine
(B) Atropine
(C) Epinephrine
(D) Hexamethonium
(E) Nicotine
Drug X causes an increase in blood pressure that is blocked by a ganglion blocker but not by a muscarinic blocker. The pressor response is actually increased by pretreatment with atropine, a muscarinic blocker, suggesting that compensatory vagal discharge might have blunted the full response. This description fits a ganglion stimulant like nicotine but not epinephrine, since epinephrine’s pressor effects are produced at α receptors, not in the ganglia. The answer is E.
A 30-year-old man has been treated with several autonomic drugs for 4 weeks. He is now admitted to the emergency department showing signs of drug toxicity. Which of the following signs would distinguish between an overdose of a ganglion blocker versus a muscarinic blocker?
(A) Cycloplegia
(B) Dry skin in a warm environment
(C) Miosis
(D) Postural hypotension
(E) Tachycardia
Neither ganglion blockers nor muscarinic blockers cause mio- sis; they cause mydriasis. Both classes of cholinoceptor block- ers increase resting heart rate and cause cycloplegia, because these are determined largely by parasympathetic tone. Simi- larly, both can cause dry skin, since this requires cholinergic transmission. Postural hypotension, on the other hand, is a sign of sympathetic blockade, which would occur with gan- glion blockers but not muscarinic blockers (Chapter 6). The answer is D.
Which of the following is an accepted therapeutic indication for the use of antimuscarinic drugs?
(A) Atrial fibrillation
(B) Botulinum poisoning
(C) Chronic obstructive pulmonary disease (COPD)
(D) Glaucoma
(E) Postoperative urinary retention
Atrial fibrillation and other arrhythmias are not responsive to antimuscarinic agents. Botulinum poisoning is associ- ated with parasympathetic blockade. Parkinson’s disease, not Huntington’s, is partially responsive to antimuscarinic drugs. Antimuscarinic drugs tend to cause urinary retention and may precipitate or exacerbate glaucoma. Bronchospasm is mediated in part by vagal outflow in many patients with COPD and in some with asthma. The answer is C.
Which of the following is an expected effect of a therapeutic dose of an antimuscarinic drug?
(A) Decreased cAMP (cyclic adenosine monophosphate) in cardiac muscle
(B) Decreased DAG (diacylglycerol) in salivary gland tissue
(C) Increased IP (inositol trisphosphate) in intestinal
3 smooth muscle
(D) Increased potassium efflux from smooth muscle
(E) Increased sodium influx into the skeletal muscle end
plat
Muscarinic M1 and M3 receptors mediate increases in IP3 and DAG in target tissues (intestine, salivary glands). M2 recep- tors (heart) mediate a decrease in cAMP and an increase in potassium permeability. Antimuscarinic agents block these effects. The answer is B.
Which one of the following drugs causes vasodilation that can be blocked by atropine?
(A) Benztropine
(B) Bethanechol
(C) Botulinum toxin (D) Cyclopentolate (E) Edrophonium (F) Neostigmine (G) Pralidoxime
Bethanechol (Chapter 7) causes vasodilation by directly acti- vating muscarinic receptors on the endothelium of blood vessels. This effect can be blocked by atropine. Indirectly acting agents (AChE inhibitors) do not typically cause vaso- dilation because the endothelial receptors are not innervated and acetylcholine is not released at this site. Pralidoxime is a distracter in this answer list. The answer is B.
Which one of the following drugs has a very high affinity for the phosphorus atom in parathion and is often used to treat life-threatening insecticide toxicity?
(A) Atropine
(B) Benztropine (C) Bethanechol (D) Botulinum
(E) Cyclopentolate (F) Neostigmine (G) Pralidoxime
Pralidoxime has a very high affinity for the phosphorus atom in organophosphate insecticides. The answer is G.
A 7-year-old boy with a previous history of bee sting allergy is brought to the emergency department after being stung by 3 bees.
1. Which of the following are probable signs of the anaphylactic reaction to bee stings?
(A) Bronchodilation, tachycardia, hypertension, vomiting, diarrhea
(B) Bronchospasm, tachycardia, hypotension, laryngeal edema
(C) Diarrhea, bradycardia, vomiting
(D) Laryngeal edema, bradycardia, hypotension, diarrhea
(E) Miosis, tachycardia, vomiting, diarrhea
- If this child has signs of anaphylaxis, what is the treatment of choice?
(A) Diphenhydramine (an antihistamine) (B) Ephedrine
(C) Epinephrine
(D) Isoproterenol
(E) Methylprednisolone (a corticosteroid)
- Anaphylaxis is caused by the release of several mediators. Leukotrienes and certain proteins are the most important of these. They cause bronchospasm and laryngeal edema and marked vasodilation with severe hypotension. Tachycardia is a common reflex response to the hypotension. Gastroin- testinal disturbance is not as common nor as dangerous. The answer is B.
- The treatment of anaphylaxis requires a powerful physiologic antagonist with the ability to cause rapid bronchodilation (β2 effect), and vasoconstriction (α effect). Epinephrine is the most effective agent with these properties. Antihistamines and corticosteroids are sometimes used as supplementary agents, but the prompt parenteral use of epinephrine is man- datory. The answer is C.
A 65-year-old woman with impaired renal function and a necrotic ulcer in the sole of her right foot is admitted to the ward from the emergency department. She has long-standing type 2 diabetes mellitus and you wish to examine her retinas for possible vascular changes. Which of the following drugs is a good choice when pupillary dilation—but not cyclople- gia—is desired?
(A) Isoproterenol (B) Norepinephrine (C) Phenylephrine (D) Pilocarpine
(E) Tropicamide
Antimuscarinics (tropicamide) are mydriatic and cycloplegic; α-sympathomimetic agonists are only mydriatic in the eye. Isoproterenol has negligible effects on the eye. Norepinephrine penetrates the conjunctiva poorly and would produce intense vasoconstriction. Pilocarpine causes miosis. Phenylephrine is well-absorbed from the conjunctival sac and produces useful mydriasis for 10–30 minutes. The answer is C.
A 60-year-old immigrant from Latin America was told she had hypertension and should be taking antihypertensive medication. She decides to take an herbal medication from an online “holistic pharmacy.” One week after starting the medication, she is found unconscious in her apartment. In the emergency department, her blood pressure is 50/0 mm Hg and heart rate is 40 bpm. Respirations are 20/min; pupils are slightly constricted. Bowel sounds are present. Which of the following would be the most effective cardiovascular stimulant?
(A) Amphetamine (B) Clonidine
(C) Isoproterenol (D) Norepinephrine (E) Tyramine
Herbal” medications often contain potent synthetic drugs in addition to (or instead of) the advertised constituents. This patient shows signs of sympathetic autonomic failure: hypo- tension, inappropriate bradycardia, constricted pupils. These signs are compatible with a large overdose of a drug that causes marked depletion of stored catecholamine transmitter such as reserpine, an obsolete but inexpensive antihypertensive agent. The indirect-acting agents (amphetamines and tyramine) act through catecholamines in (or released from) the nerve termi- nal and would therefore be ineffective in this patient. Cloni- dine acts primarily on presynaptic nerve endings although it can activate α2 receptors located elsewhere. Isoproterenol would stimulate the heart but has no α-agonist action and might exacerbate the hypotension. Norepinephrine has the necessary combination of direct action and a spectrum that includes α1, α2, and β1 effects. The answer is D.
A group of volunteers are involved in a phase 1 clinical trial of a new autonomic drug. When administered by intravenous bolus, the blood pressure increases. When given orally for 1 week, the blood pressure decreases. Which of the following standard agents does the new drug most resemble?
(A) Atropine
(B) Clonidine
(C) Phentolamine (an α blocker) (D) Phenylephrine
(E) Propranolol (a β blocker)
The dual blood pressure effects of the drug suggest that ini- tially it is causing a direct α-agonist vasoconstrictor effect, but when given for a week, it is accumulating in a blood pressure-controlling center, eg, the CNS, and reducing sym- pathetic outflow. The answer is B.
Your 30-year-old patient has moderately severe new onset asthma, and you prescribe a highly selective β2 agonist inhaler to be used when needed. In considering the possible drug effects in this patient, you would note that β2 stimulants frequently cause
(A) Direct stimulation of renin release
(B) Hypoglycemia
(C) Itching due to increased cGMP (cyclic guanine mono-
phosphate) in mast cells (D) Skeletal muscle tremor (E) Vasodilation in the skin
Tremor is a common β2 effect. Blood vessels in the skin have almost exclusively α (vasoconstrictor) receptors. Stimulation of renin release is a β1 effect. Beta2 agonists cause hyperglyce- mia and have little effect on cGMP. The answer is D.
Mr Green, a 54-year-old banker, had a cardiac transplant 6 months ago. His current blood pressure is 120/70 mm Hg and heart rate is 100 bpm. Which of the following drugs would have the least effect on Mr Green’s heart rate?
(A) Albuterol
(B) Epinephrine (C) Isoproterenol (D) Norepinephrine (E) Phenylephrine
Heart transplantation involves cutting of the autonomic nerves to the heart. As a result, autonomic nerve endings degenerate, and cardiac transmitter stores are absent for 2 years or longer after surgery. Therefore, indirect-acting sympathomimetics are ineffective in changing heart rate. All the drugs listed are direct-acting, and all but phenylephrine have significant effects on β receptors. Phenylephrine usually causes reflex bradycardia, which requires intact vagal innerva- tion. The answer is E. (Note that denervation may result in upregulation of both β1 and β2 receptors so that direct-acting β agonists may have a greater than normal effect.)
A patient is to receive epinephrine. She has previously received an adrenoceptor-blocking agent. Which of the fol- lowing effects of epinephrine would be blocked by phentol- amine but not by metoprolol?
(A) Cardiac stimulation
(B) IncreaseofcAMP(cyclicadenosinemonophosphate)in
fat
(C) Mydriasis
(D) Relaxation of bronchial smooth muscle (E) Relaxation of the uterus
Mydriasis caused by contraction of the pupillary dilator radial smooth muscle is mediated by α receptors. All the other effects listed are mediated by β receptors. The answer is C.
Clinical studies have shown that adrenoceptor blockers have many useful effects in patients. However, a number of drug toxicities have been documented. Adverse effects that limit the use of adrenoceptor blockers include which one of the following?
(A) Bronchoconstriction from α-blocking agents (B) Acute heart failure exacerbation from β blockers (C) Impaired blood sugar response with α blockers (D) Increased intraocular pressure with β blockers (E) Sleep disturbances from α-blocking drugs
Although chronic heart failure is often treated with certain β blockers, acute heart failure can be precipitated by these drugs. Choices A, C, and E reverse the correct pairing of receptor subtype (α versus β) with effect. Choice D reverses the direc- tion of change of intraocular pressure. The answer is B.
Four new synthetic drugs (designated W, X, Y, and Z) are to be studied for their cardiovascular effects. They are given to 4 anesthetized animals while the heart rate is recorded. The first animal has received no pretreatment (control); the sec- ond has received an effective dose of hexamethonium; the third has received an effective dose of atropine; and the fourth has received an effective dose of phenoxybenzamine. The net changes induced by W, X, Y, and Z in the animals are described in the following questions.
Drug W increased heart rate in the control animal, the atropine-pretreated animal, and the phenoxybenzamine- pretreated animal. However, drug W had no effect on heart rate in the hexamethonium-pretreated animal. Drug W is probably a drug similar to
(A) Acetylcholine (B) Edrophonium (C) Isoproterenol (D) Nicotine
(E) Norepinephrine
In developing a strategy for this type of question, consider first the actions of the known blocking drugs. Hexamethonium blocks reflexes as well as the direct action of nicotine. Atropine would block direct muscarinic effects of an unknown drug (if it had any) or reflex slowing of the heart mediated by the vagus. Phenoxybenzamine blocks only α-receptor-mediated processes. If the response produced in the nonpretreated ani- mal is blocked or reversed by hexamethonium, it is probably a direct nicotinic effect or a reflex response to hypotension. In that case, consider all the receptors involved in mediating the reflex. Drug W causes tachycardia that is prevented by gan- glion blockade. The only drug in the list of choices that causes hypotension and tachycardia that is not blocked by atropine is isoproterenol, and the tachycardia caused by isoproterenol is not blocked by ganglionic blockade. Thus, drug W must be nicotine or a drug similar to it. The answer is D.
