Question

A CO2 molecule bound to hemoglobin and being unloaded from an alveolar capillary into the alveolar airspace would diffuse through, in order from first to last:

		cytoplasm of RBC, RBC cell membrane, plasma, endothelial cell, basement membrane, epithelial cell, fluid with surfactant
		fluid with surfactant, epithelial cell, basement membrane, endothelial cell, plasma, cytoplasm of RBC
		cytoplasm of RBC, RBC cell membrane, plasma, epithelial cell, basement membrane, endothelial cell, fluid with surfactant
		fluid with surfactant, epithelial cell, basement membrane, cytoplasm of RBC, RBC membrane, plasma, endothelial cell
		fluid with surfactant, type II epithelial cell, basement membrane, plasma, endothelial cell

Answer 1

Answer

Option A) Cytoplasm of RBC RBC cell membrane plasma endothelial cell basement membrane epithelial cell fluid with surfactant.

• The cytoplasm of RBC contains a protein called hemoglobin.
• About 20% of carbon doxide binds to the hemoglobin in blood.
• During external repiration, the cabon dioxide molecule unloads from the hemoglobin into the cytoplasm of RBC, cross cell membrane to reach the plasma.
• It diffuses through capillary endothelial wall , fused basement membrane and the epithelial cell membrane of type I alveolar cell.
• It finally reaches into the alveoli that contains surfactant secreted by type II alveolar cells.