Which of the following body systems is NOT directly influenced by kidney function?

Correct Answer: D

Rationale: Skeletal system isn't directly influenced by kidneys bones respond indirectly via vitamin D (e.g., calcium). Cardiovascular is BP/volume direct. Respiratory ties to pH HCO₃⁻ effect. Endocrine involves hormones (renin) direct. Skeletal's indirect link distinguishes it, critical for system specificity, unlike directly impacted systems.

Correct Answer: C

Rationale: Nitrogen for excretion comes from protein deamination e.g., liver converts amino acids to urea. Carbohydrates yield COâ‚‚/Hâ‚‚O not nitrogen. Nitric buffer isn't a system false. Atmosphere provides Oâ‚‚ not waste N. Deamination distinguishes it, critical for nitrogen source, unlike carbs or external origins.

Correct Answer: D

Rationale: Aldosterone antagonist (e.g., spironolactone) reduces Na /water reabsorption lowers blood volume (e.g., less retention). Urine volume rises not falls. K concentration rises retained. Viscosity unchanged volume-based. Volume drop distinguishes it, key to antagonist effect, unlike urine or K missteps.

Correct Answer: A

Rationale: Vasa recta is a capillary network around Loop of Henle e.g., countercurrent exchanger maintains gradient. Urethra is exit not capillaries. Hypothalamus makes ADH not vasa recta. Zona glomerulosa is aldosterone not vascular. Capillary role distinguishes it, key to medullary osmolality, unlike tubes or hormones.