Pharmacology Autonomic Nervous System Agents 3

Question 1

A nurse administers epinephrine 1:1000 intramuscularly for anaphylaxis. At therapeutic doses, what is the PRIMARY cardiovascular effect?

Accepted Answer

Increased heart rate and increased systolic blood pressure with decreased diastolic pressure

Answer

Epinephrine increases heart rate and contractility (beta-1) and increases systolic BP while beta-2-mediated vasodilation in skeletal muscle decreases diastolic BP.

Question 2

Which of the following beta-blockers has intrinsic sympathomimetic activity (ISA) and is least likely to cause bradycardia at rest?

Accepted Answer

Pindolol

Answer

Pindolol has ISA, acting as a partial agonist at beta receptors, which maintains baseline heart rate while still blocking excessive sympathetic stimulation.

Question 3

Clonidine's antihypertensive effect is mediated by stimulation of which receptors in the CNS?

Accepted Answer

Alpha-2 adrenergic receptors in the locus coeruleus and brainstem

Answer

Clonidine activates presynaptic alpha-2 receptors in the brainstem, reducing sympathetic outflow and lowering blood pressure.

Question 4

A patient with urinary retention post-operatively is given bethanechol. What is its mechanism of action?

Accepted Answer

Direct muscarinic receptor agonist that stimulates detrusor muscle contraction

Answer

Bethanechol directly activates muscarinic receptors on the detrusor muscle, promoting bladder contraction and urination.

Question 5

During a stress test, a patient is given isoproterenol. Which hemodynamic effect distinguishes it from epinephrine?

Accepted Answer

Isoproterenol decreases diastolic blood pressure more than epinephrine due to pure beta-2 vasodilation

Answer

Isoproterenol is a pure beta agonist; its beta-2 vasodilation lowers diastolic BP without alpha-mediated vasoconstriction, unlike epinephrine.

Pharmacology Practice Test

Pharmacology Practice Test

Pharmacology Autonomic Nervous System Agents 3