Where does the ADH dependent reabsorption occur?

Correct Answer: C

Rationale: Antidiuretic hormone (ADH) regulates water reabsorption primarily in the medullary collecting duct. ADH increases the insertion of aquaporin-2 water channels into the apical membrane, allowing water to move from the tubular lumen into the hyperosmotic medullary interstitium, concentrating urine. The proximal tubule and Loop of Henle reabsorb water independently of ADH, and the distal tubule has minor ADH effects, making the medullary collecting duct the key site, thus C is correct.

Correct Answer: B

Rationale: Sympathetic activity constricts both afferent and efferent arterioles, reducing renal blood flow and GFR. Lower GFR decreases the filtered Na⁺ load, but slower filtrate flow allows less Na⁺ reabsorption in the PCT, increasing Na⁺ delivery to the macula densa in the distal tubule. GFR doesn't increase (A), PCT reabsorption decreases (C), and filtered load drops (D), making B correct.

Correct Answer: B

Rationale: Carbonic acid ([H₂CO₃]) in blood is very low (~0.001 mM) and unstable, rapidly dissociating into CO₂ and H₂O, making direct measurement difficult. It's estimated via PCO₂ (0.03 × PCO₂ in Henderson-Hasselbalch). It remains effective in the bicarbonate buffer equation (C is false), and no replacement is needed (D), making B correct.

Correct Answer: D

Rationale: The evaluation phase of the nursing process involves reassessment and audit (D) to determine if outcomes were met, adjusting care as needed. Data collection (A) is assessment, decision-making (B) and priority-setting (C) occur in planning, making D the primary evaluation action.

Correct Answer: C

Rationale: The kidneys regulate acid-base balance by excreting H⁺ and reabsorbing HCO₃⁻ (opposite of C), making this statement incorrect and needing education. Filtration (A), reabsorption (B), and secretion (D) are accurate, highlighting C as the error.