A patient has a dead space of 150 milliliters, FRC of 3 liters, VT of 650 milliliters, ERV of 1.5 liters, TLC of 8 liters, and respiratory rate of 15 breaths/min. What is the alveolar ventilation (Va)?

Correct Answer: B

Rationale: Alveolar ventilation (VA) = (VT - VD) × RR, where VT (tidal volume) = 650 ml, VD (dead space) = 150 ml, RR = 15/min. VA = (650 - 150) × 15 = 500 × 15 = 7500 ml/min = 7.5 L/min. Verify: FRC = ERV (1.5 L) + RV (1.5 L) = 3 L; TLC = FRC + IC (VT + IRV) = 8 L, consistent. Total ventilation (VE) = 650 × 15 = 9750 ml/min = 9.75 L/min, with dead space ventilation = 150 × 15 = 2250 ml/min, leaving VA = 9.75 - 2.25 = 7.5 L/min. The 7.5 L/min reflects air reaching alveoli, key for gas exchange, aligning with respiratory calculations and matching option B.

Correct Answer: D

Rationale: Foreign bodies aspirated into the respiratory tract favor the right lung due to its wider, more vertical bronchus. The right main bronchus splits into upper, middle, and lower lobe bronchi. The lower lobe's posterior basal (apicobasal, D) segment is most common for gravity-dependent lodging in an upright position, unlike upper (A) or middle (C) lobes. The left lung (A, B) is less likely due to its oblique bronchus. D aligns with anatomical and clinical patterns.

Correct Answer: C

Rationale: Recurrent laryngeal nerve injury paralyzes all intrinsic muscles except cricothyroid, but posterior cricoarytenoid (C) abducts cords its loss leaves cords adducted, closing rima. C is correct.

Correct Answer: A

Rationale: Transitional epithelium lines the ureter (A), bladder, and urethra, stretching as urine fills these structures. Its stratified cells shift from cuboidal to flat, adapting to tension. The intestine (B) has simple columnar epithelium for absorption, not stretching. The epidermis (C) is stratified squamous, protective, not transitional. Alveoli (D) use simple squamous for gas exchange, not stretch. A is correct transitional epithelium's unique adaptability suits the ureter's urinary role, unlike the others' distinct functions.

Correct Answer: D

Rationale: Endoderm forms liver (A), pancreas (B), and thyroid (C), via foregut and midgut outgrowths. Dermis (D) derives from mesoderm, forming skin's connective layer, not endoderm. D is the exception its mesodermal origin distinguishes it from endodermal derivatives.