it is because for the diffusion of water and oxygen molecules
Capillaries need to have very thin walls so that nutrients and oxygen can easily pass through those walls to supply the cells of the body.
They walls are a single layer of squamous epithelial cells.
capillaries
Epithelial tissue exists in stratified and single layers.
Simple epithelial cells.
Simple Squamous epithelial cells are found in the lung (alveoli), lining the lumen of blood vessels, and lymphatic vessels, and also in the kidneys.
alveoli
Yes it is. Infact, the alveolus is made up of a single layer of epithelial tissue.
The alveoli consist of an epithelial layer and extracellular matrix surrounded by capillaries.
The alveoli in the lungs are made of a wet wall that is one cell thick with a network of capillaries to facilitate gas exchange.
If epithelial cells are more than one layer thick, it is considered stratified epithelial tissue.
The outer layer of our skin is composed of dead epithelial cells.
Saquamous cells are flat cells. Single cell layer of these squamous cells is called saqumous cell epithelium. The stratified epithelium means formed of layers [strata] of cells which may or may not be squamous cells. The functions of these layers are different.