NEET PG DENTAL EXAM

Detailed explanation-1: -The layers of cells lining the alveoli and the surrounding capillaries are each only one cell thick and are in very close contact with each other.

Detailed explanation-2: -Capillaries are the connection of the smallest branches of arteries and veins. The capillary walls are one cell thick. Capillaries allow molecules to pass through across the capillary walls. This exchange of materials is not possible across the walls of other types of blood vessels because the walls are too thick.

Detailed explanation-3: -Capillary walls consist of a single layer of flattened endothelial cells, the endothelia, and these cells constitute the barrier between the blood and the ISF. Electron microscopy has revealed that endothelial cells in different tissues are of two distinct types: “continuous” and “fenestrated” (Figure 9.1).