Matching lung diagram labels to specialized structures

Steps:

• Identify carbonic anhydrase in red blood cells where it catalyzes CO2 + H2O to H2CO3, forming HCO3- ions for transport.
• Locate HCO3- ions in the same red blood cells after the reaction, exchanged via chloride shift.
• Pinpoint lysosomes in alveolar macrophages, used for digesting engulfed debris and pathogens.
• Compare choices to diagram: C assigns carbonic anhydrase to 3 (RBC interior), HCO3- to 5 (RBC cytoplasm), lysosomes to 6 (macrophage granules).

Why C is correct:

• C aligns with standard lung histology: label 3 in RBC enzyme site, 5 for bicarbonate pool, 6 for lysosomal bodies per cellular function definitions.

Why the others are wrong:

• A misplaces lysosomes in non-phagocytic tissue (label 4).
• B assigns HCO3- to capillary space (label 4), not intracellular RBC.
• D puts carbonic anhydrase in extracellular fluid (label 4), violating enzyme localization.

Final answer: C