Epithelial Tissues Lab

Simple Squamous Epithelium

Simple squamous epithelia consist of a single layer of flattened cells. This type of epithelia lines the inner surface of all blood vessels (endothelium), forms the wall of alveolar sacs in the lung and lines the body cavities (mesothelium). The primary function of simple squamous epithelia is to facilitate diffusion of gases and small molecules. 

Simple Cuboidal Epithelium

Simple cuboidal epithelium consist of a single layer of cells that are approximately as tall as they are wide. This type of epithelium lines collecting ducts and tubes and is involved in absorbing or secreting material into the ducts or tubes. 

Simple Columnar Epithelium

Simple columnar epithelium consist of a single layer of cells that are taller than they are wide. This type of epithelia lines the small intestine where it absorbs nutrients from the lumen of the intestine. Simple columnar epithelia are also located in the stomach where it secretes acid, digestive enzymes and mucous. 

Stratified Squamous Epithelium

Stratified squamous epithelia consist of multiple layers of cells with the outer most layer being squamous. The other layers may contain cells that are cuboidal and/or columnar, but the classification of the epithelium is based only on the shape of the outermost layer of cells. This type of epithelium provides protection to mechanical stress and dessication and is found in the skin.

Pseudostratified Epithelium

Pseudostratified epithelia consist of a single layer of cells, but due to the different heights of the cells, it gives the appearance of having mutliple layers of cells, hence the name pseudostratified. Importantly, all cells are attached to the basement membrane. This type of epithelium is found in the respiratory tract and functions to secrete mucous and move material up the respiratory tract through the beating of cilia.