Alveoli, capillaries, and glomeruli capsules are all lined with simple squamous epithelium. what function is shared by these structures?

The common function shared by alveoli, capillaries and glomerular capsules are lined with simple squamous epithelium so they are all involved where absorption  or transport of the materials occur.  The function of the squamous epithelium is mainly selective transmembrane transportation either by using the concentration gradient or by active transport by using the membrane bound carrier proteins.

The pulmonary alveoli are highly vascular in structure and are formed by a layer of the squamous epithelial cells and a network of capillaries.

The capillaries are also made up of squamous epithelial cells and gas exchange between the alveoli and blood vessels occurs through these capillaries.

The common function of alveoli, capillaries, and glomeruli capsules is rapid diffusion of substances.