Most of the body's water is found in the

Correct Answer: D

Rationale: Most body water (~60%) is in cells intracellular fluid (e.g., ~40 L in 70 kg adult). Plasma is ~3 L small fraction. Lymph is minimal circulatory subset. Tissue fluid (interstitial) is ~15% less than cells. Cellular dominance distinguishes it, critical for hydration, unlike extracellular options.

Correct Answer: C

Rationale: pH above 7.4 is alkalosis base excess (e.g., HCO₃⁻ rise). Acidosis is below 7.35 acidic. Diuresis is urine output not pH. Natriuresis is Na excretion unrelated. Alkalosis's high pH distinguishes it, critical for acid-base status, unlike low pH or unrelated terms.

Correct Answer: B

Rationale: Hemodialysis removes 8-25 g urea in 3-6 hours e.g., typical clearance (blood levels drop). 8-10 g is low underestimates. 50-250 g is excessive beyond capacity. 8-25 mg is trivial mg vs. g error. 8-25 g distinguishes it, critical for dialysis efficacy, unlike under/over or unit mistakes.

Correct Answer: C

Rationale: Distal tubules are impermeable to renin it's a hormone, not reabsorbed (e.g., acts systemically). Aldosterone affects Na cells respond. ADH adjusts water collecting duct permeable. Macula densa is a structure not a substance. Renin's impermeability distinguishes it, key to its systemic role, unlike hormones affecting tubules.

Correct Answer: B

Rationale: In alkalosis, kidneys excrete HCO₃⁻ less CO₂ binding allows loss (e.g., distal tubule adjustment). More Na reabsorption doesn't fix base excess unrelated. Angiotensin/ADH affects water not pH directly. K absorption is minor irrelevant. HCO₃⁻ excretion distinguishes it, critical for pH correction, unlike Na or K shifts.