Autonomic Nervous System Agents Flashcards
7 cards from real Pharmacology practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Autonomic Nervous System Agents flashcards as text
A nurse administers epinephrine 1:1000 intramuscularly for anaphylaxis. At therapeutic doses, what is the PRIMARY cardiovascular effect?
Answer: Increased heart rate and increased systolic blood pressure with decreased diastolic pressure
Epinephrine increases heart rate and contractility (beta-1) and increases systolic BP while beta-2-mediated vasodilation in skeletal muscle decreases diastolic BP.
Which of the following beta-blockers has intrinsic sympathomimetic activity (ISA) and is least likely to cause bradycardia at rest?
Answer: Pindolol
Pindolol has ISA, acting as a partial agonist at beta receptors, which maintains baseline heart rate while still blocking excessive sympathetic stimulation.
Clonidine's antihypertensive effect is mediated by stimulation of which receptors in the CNS?
Answer: Alpha-2 adrenergic receptors in the locus coeruleus and brainstem
Clonidine activates presynaptic alpha-2 receptors in the brainstem, reducing sympathetic outflow and lowering blood pressure.
A patient with urinary retention post-operatively is given bethanechol. What is its mechanism of action?
Answer: Direct muscarinic receptor agonist that stimulates detrusor muscle contraction
Bethanechol directly activates muscarinic receptors on the detrusor muscle, promoting bladder contraction and urination.
During a stress test, a patient is given isoproterenol. Which hemodynamic effect distinguishes it from epinephrine?
Answer: Isoproterenol decreases diastolic blood pressure more than epinephrine due to pure beta-2 vasodilation
Isoproterenol is a pure beta agonist; its beta-2 vasodilation lowers diastolic BP without alpha-mediated vasoconstriction, unlike epinephrine.
Timolol eye drops used for glaucoma can cause systemic bronchospasm because timolol is a:
Answer: Non-selective beta-blocker that blocks pulmonary beta-2 receptors
Timolol is non-selective for beta receptors; systemic absorption through the nasolacrimal duct allows it to block bronchial beta-2 receptors causing bronchospasm.
Which muscarinic receptor subtype primarily mediates bradycardia when the vagus nerve is stimulated at the sinoatrial node?
Answer: M2
M2 receptors in the SA node mediate vagal bradycardia by activating K+ channels (IKACh), hyperpolarizing the cell and slowing spontaneous depolarization.