A male patient's X-ray result reveals bilateral white-outs, indicating acute respiratory distress syndrome (ARDS). This syndrome results from:

Correct Answer: C

Rationale: The correct answer is C: Increased pulmonary capillary permeability. ARDS is characterized by damage to the alveolar-capillary membrane, leading to increased permeability and leakage of fluid into the alveoli. This causes bilateral white-outs on X-ray. Cardiogenic pulmonary edema (A) results from heart failure, not ARDS. Respiratory alkalosis (B) is a condition of elevated blood pH due to hyperventilation, not a direct cause of ARDS. Renal failure (D) is not a direct cause of ARDS, although it can contribute to fluid overload. Thus, the most accurate choice is C due to the pathophysiological mechanism of ARDS.

Correct Answer: C

Rationale: The correct answer is C: Relax smooth muscles of the bronchial airway. Aminophylline (theophylline) is a bronchodilator that works by relaxing the smooth muscles in the bronchial airways, which helps to open up the airways and improve airflow. This action helps to relieve bronchospasm, which is common in conditions like acute bronchitis. Promoting expectoration (A) and suppressing cough (B) are not the primary actions of aminophylline, although they may be secondary effects. Preventing infection (D) is unrelated to the mechanism of action of aminophylline in treating acute bronchitis.

Correct Answer: B

Rationale: The correct answer is B: A lobe of the lung. During a lobectomy, a lobe of the lung is surgically removed, typically to treat lung cancer while preserving the remaining lung tissue. Removing one entire lung (choices A and D) is not necessary for a lobectomy and would be a more extensive procedure. Choice C, removing a small localized area near the surface of the lung, does not accurately reflect the extent of tissue removal required for a lobectomy. Therefore, the correct choice is B as it specifically addresses the removal of a lobe during the surgical procedure.

Correct Answer: B

Rationale: During inhalation, the diaphragm contracts and moves downward, increasing the volume of the thoracic cavity. This decrease in pressure within the thoracic cavity creates a pressure gradient, causing air to flow into the lungs where the pressure is now higher. Choice B is correct because the pressure in the thoracic cavity is indeed less than the pressure within the lungs during inhalation. Choices A, C, and D are incorrect because during inhalation, the pressure in the thoracic cavity decreases, the diaphragm moves downward and flattens, and the chest cavity volume increases to allow for air intake.

Correct Answer: B

Rationale: The correct answer is B: internal respiration. This process refers to the exchange of gases between blood and body cells. Pulmonary ventilation (A) is the process of breathing, moving air in and out of the lungs. External respiration (C) is the exchange of gases between the lungs and blood. Cellular respiration (D) is the process where cells use oxygen to produce energy. Internal respiration best describes the exchange of gases at the cellular level.