Correct option is A
Explanation:
Let's evaluate each statement regarding lung surfactant and its proteins:
A. Surfactant protein B (SP-B) and surfactant protein C (SP-C) are the key protein members of monomolecular film of surfactant.
This statement is correct.
Surfactant proteins B (SP-B) and C (SP-C) are critical components of the lung surfactant system. They help form a monomolecular film of surfactant that lowers the surface tension in the alveoli, preventing alveolar collapse during exhalation. Hence, A is true.
B. Surfactant protein A (SP-A) is a large glycoprotein and has a collagen-like domain within its structure.
This statement is correct.
Surfactant protein A (SP-A) is indeed a large glycoprotein that plays a role in the immune defense of the lungs. It contains a collagen-like domain which is important for its function in lung surfactant metabolism and immune modulation. Therefore, B is true.
C. SP-A does not play any role in the feedback uptake of surfactant by the type II alveolar epithelial cells.
This statement is incorrect.
Surfactant protein A (SP-A) plays a crucial role in the feedback uptake of surfactant by type II alveolar epithelial cells. SP-A helps regulate surfactant production and uptake, making this statement false.
D. The formation of phospholipid film lining the alveoli is inhibited by the proteins in surfactant.
This statement is incorrect.
The proteins in lung surfactant, especially SP-B and SP-C, are essential for the formation and stabilization of the phospholipid film lining the alveoli. These proteins enhance the formation of the phospholipid film, not inhibit it. Hence, D is false.
Conclusion:
Statements A and B are correct.
Statements C and D are incorrect.
