17. In order for oxygen in the inspired air to reach hemoglobin, it must diffuse across all of the

following structures, except:

A) layer of surfactant

B) an endothelial cell

C) a type I pneumocyte

D) the plasma membrane of the erythrocyte

E) one or two smooth muscle cells

Option E.

In order for oxygen in the inspired air to reach hemoglobin, it must diffuse across all of the following structures, except: one or two smooth muscle cells.

Explanation:

In the process of oxygen reaching hemoglobin it gets diffused across layer of surfactant, an endothelial cell, type I pneumocyte, and the plasma membrane of the erythrocyte. The molecule that is responsible for the carrying of oxygen into the blood cells is protein hemoglobin. The normal adult human's blood is the mixture of six different species of hemoglobin molecules. These all molecules consist of same function as well as structure.