A client is admitted to the hospital for shortness of breath and chest pain after an episode of syncope. Which laboratory finding is most important for the nurse to report to the healthcare provider?

Correct Answer: C

Rationale: Troponin I is the most important lab finding to report in a client with shortness of breath, chest pain, and syncope. These symptoms suggest a cardiac event like myocardial infarction, and troponin I is a specific marker of myocardial injury, guiding diagnosis and treatment (e.g., catheterization). Hematocrit reflects blood volume, glucose relates to metabolic issues, and oxygen saturation, while critical, is a vital sign, not a lab test. Troponin's elevation indicates urgent cardiac damage needing immediate attention.

Correct Answer: B

Rationale: Aldosterone is a key factor affecting sodium reabsorption. This hormone, released from the adrenal cortex, acts on principal cells in the collecting duct and distal tubule, increasing Na⁺/K⁺-ATPase and epithelial sodium channel (ENaC) activity. This enhances Na⁺ reabsorption, retaining salt and water to raise blood volume and pressure. While GFR, estrogens, and natriuretic hormone also influence Na⁺ handling, aldosterone's direct and potent effect makes it a standout choice, thus B is correct.

Correct Answer: B

Rationale: When delaying urination despite a full bladder, the brain inhibits the micturition reflex by activating somatic control via the pudendal nerve, which maintains external urethral sphincter contraction. The pelvic nerve (parasympathetic) drives detrusor contraction, hypogastric nerve (sympathetic) relaxes it, but pudendal inhibition prevents voiding, making B correct.

Correct Answer: A

Rationale: The hypothalamic thirst center is activated by significant triggers: a 10-15% drop in plasma volume (hypovolemia) or a 1-2% rise in plasma osmolality (hyperosmolality), detected by osmoreceptors and baroreceptors. These thresholds prompt thirst to restore fluid balance. Smaller changes (B) are insufficient, and C and D are outcomes, not stimuli, making A correct.

Correct Answer: C

Rationale: In bicarbonate buffering, excess H⁺ binds with HCO₃⁻ to form H₂CO₃ (C), which then dissociates into CO₂ and H₂O (A), exhaled by lungs. This sequence neutralizes acid. HCO₃⁻ isn't converted to H₂CO₃ first (B), and ‘all' (D) ignores order, making C the correct initial step.