This document discusses epithelial tissue and its functions. There are several types of epithelial tissue based on cell shape and layering, including simple squamous, simple cuboidal, simple columnar, pseudostratified, stratified squamous, and stratified columnar. Epithelial tissue forms coverings and linings and has functions like protection, absorption, secretion, sensation, and contractility. Epithelial cells are polarized and joined by various junctions. Nutrients diffuse across the basal lamina to nourish epithelial cells, which renew through mitotic division.