What keeps alveoli from collapsing?

Correct Answer: B

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: C

Rationale: The correct answer is C because mammalian RBCs lack mitochondria, which are responsible for aerobic respiration. Without mitochondria, RBCs are unable to perform oxidative phosphorylation to generate ATP aerobically. Stroma (A) is found in chloroplasts, not RBCs. Hemoglobin (B) is responsible for oxygen transport, not cellular respiration. Bicarbonate ions (D) are involved in the buffering system of blood, not in cellular respiration. Therefore, the lack of mitochondria is the key reason for RBCs to respire anaerobically.

Correct Answer: C

Rationale: The correct answer is C: To keep electrostatic neutrality of RBC membrane. Chloride shift helps maintain the balance of charges inside and outside red blood cells (RBCs) to prevent excessive positive or negative charges, ensuring the electrostatic neutrality of the RBC membrane. This process involves the exchange of chloride ions between the plasma and RBCs, with chloride moving into the RBCs to balance the outflow of bicarbonate ions during the transport of CO2. Choices A, B, and D are incorrect as they do not directly relate to the primary function of chloride shift, which is to maintain the electrostatic neutrality of the RBC membrane. Hemoglobinic acid formation, bicarbonate formation, and CO2 transport are secondary outcomes of the chloride shift process, but the main purpose is to regulate the charge balance within the RBCs.

Correct Answer: D

Rationale: The correct answer is D because Chronic Obstructive Pulmonary Disease (COPD) is an umbrella term that encompasses both emphysema and bronchitis. Emphysema is characterized by damage to the air sacs in the lungs, while bronchitis involves inflammation of the bronchial tubes. Asthma, on the other hand, is a separate condition characterized by reversible airway obstruction. Therefore, choices A, B, and C are incorrect, as only emphysema and bronchitis fall under the category of COPD.

Correct Answer: C

Rationale: The correct answer is C. Lung fields dull to percussion, absent breath sounds, and a pleural friction rub are consistent with pleural effusion. Dullness on percussion indicates fluid accumulation in the pleural space. Absent breath sounds suggest decreased air movement due to the fluid. A pleural friction rub may be heard due to inflammation of the pleura. A is incorrect because increased tactile fremitus, egophony, and a dull sound upon percussion are more indicative of pneumonia. B is incorrect because decreased tactile fremitus, wheezing, and a hyperresonant sound upon percussion are more indicative of COPD or emphysema. D is incorrect because normal tactile fremitus, decreased breath sounds, and a resonant sound upon percussion are more indicative of asthma or atelectasis.