Which method of transport is used for peptides in the process of reabsorption?

Correct Answer: C

Rationale: Peptides in the proximal convoluted tubule are reabsorbed via endocytosis. Filtered peptides are taken up by apical microvilli into tubular cells, where they're broken down into amino acids and released into the blood. This receptor-mediated process differs from facilitated diffusion (glucose), active transport (Na⁺), or passive diffusion (urea), making C correct.

Correct Answer: C

Rationale: Isolation reduces sensory input, and in an 80-year-old, this sensory deprivation (C) can cause confusion, hallucinations, and reduced comprehension, especially with limited stimulation. Fluid/electrolyte imbalance (A) lacks supporting data (e.g., labs), a stimulating environment (B) contradicts isolation, and sundowning (D) ties to evening confusion, not isolation, making C the likely cause.

Correct Answer: C

Rationale: During the resting (filling) stage of micturition, the detrusor muscle, a smooth muscle in the bladder wall, contracts minimally and stretches to accommodate urine (C), maintaining continence with sphincter tone. Urination (A) and sphincter relaxation (B) occur during voiding, and control (D) is broader, making C correct.

Correct Answer: D

Rationale: Mesangial cells contract to reduce filtration area (A), not produce systemic angiotensin II (B, a juxtaglomerular cell role), and phagocytose debris (C). A and C are true—contraction adjusts GFR, phagocytosis clears mesangium—while B is false, making D (A and C are correct) the answer.

Correct Answer: D

Rationale: Using Henderson-Hasselbalch: pH = 6.1 + log([HCO₃⁻]/(0.03 × pCO₂)), 7.60 = 6.1 + log([HCO₃⁻]/(0.03 × 40)). Solving: 1.5 = log([HCO₃⁻]/1.2), 10^1.5 = [HCO₃⁻]/1.2, 31.6 ≈ [HCO₃⁻]/1.2, [HCO₃⁻] ≈ 40 mEq/L. D (40) matches, indicating alkalosis.