What is the primary function of squamous epithelium?

The primary function of squamous epithelium is indeed to facilitate passage for small molecules. This type of epithelium consists of flat, thin cells that create a minimal barrier to diffusion, allowing for the efficient exchange of gases, nutrients, and waste products. This characteristic is particularly important in areas where rapid transport is necessary, such as in the alveoli of the lungs, where oxygen and carbon dioxide exchange occurs, or in the lining of blood vessels (endothelium), where substances are transferred between blood and surrounding tissues.

Squamous epithelial cells' thinness and flat shape minimize the distance across which substances must diffuse, enhancing transport efficiency. This function is critical in various physiological processes where selective permeability is required to maintain homeostasis in the body.