A patient is started on a diuretic for antihypertensive therapy. The nurse expects that a drug in which class is likely to be used initially?

Correct Answer: C

Rationale: The correct answer is C: Thiazide diuretics. Thiazide diuretics are commonly used as first-line therapy for hypertension due to their effectiveness in reducing blood pressure by promoting diuresis. They work by inhibiting sodium reabsorption in the distal convoluted tubule, leading to decreased fluid volume and lower blood pressure. Thiazides are well-tolerated and have shown to reduce cardiovascular events in hypertensive patients. Loop diuretics (A) are more potent and are typically reserved for patients with more severe fluid overload conditions. Osmotic diuretics (B) are used for acute renal failure or cerebral edema, not for hypertension. Potassium-sparing diuretics (D) are typically used in combination with thiazides to prevent hypokalemia, not as initial therapy.

Correct Answer: D

Rationale: The correct answer is D: cAMP. G-protein-coupled receptors activate adenylyl cyclase, leading to the production of cAMP, which acts as the second messenger. cAMP then triggers downstream signaling cascades. Choice A (Adenylyl cyclase) is the enzyme activated by G-protein-coupled receptors, not a second messenger itself. Choice B (Sodium ions) is not typically involved in GPCR signaling pathways. Choice C (Phospholipase C) generates inositol trisphosphate and diacylglycerol, which are part of a separate signaling pathway, not the second messenger system for GPCRs.

Correct Answer: A

Rationale: The correct answer is A because Type A delta and C fibers are known to participate in high-frequency pain transmission. Type A delta fibers transmit sharp, localized pain signals, while Type C fibers transmit dull, aching pain signals. Choice B, Type A alpha fibers, are responsible for transmitting proprioceptive information. Choice C, Type B fibers, are not involved in pain transmission. Choice D, Type A beta fibers, are responsible for touch and pressure sensations, not high-frequency pain transmission. Therefore, based on the characteristics of each fiber type, Type A delta and C fibers are the correct choice for high-frequency pain transmission.

Correct Answer: A

Rationale: The correct answer is A: Physostigmine, which penetrates the blood-brain barrier. Physostigmine is a reversible cholinesterase inhibitor that can cross the blood-brain barrier, allowing it to exert its effects on cholinesterase enzymes in the central nervous system. This property makes it useful in conditions where increasing cholinergic activity in the brain is desired, such as in the treatment of Alzheimer's disease. Choice B, Edrophonium, is a reversible cholinesterase inhibitor but does not effectively penetrate the blood-brain barrier. Choice D, Neostigmine, is also a reversible cholinesterase inhibitor but is primarily used for its effects on peripheral cholinesterase enzymes and does not cross the blood-brain barrier effectively.

Correct Answer: D

Rationale: The correct answer is D: Atracurium. Atracurium is metabolized to laudanosine, which readily crosses the blood-brain barrier and may cause seizures. Pancuronium (A) does not readily cross the blood-brain barrier. Succinylcholine (B) does not have a breakdown product that crosses the blood-brain barrier. Tubocurarine (C) does not produce a breakdown product that causes seizures.