The human body consists of four types of tissue: epithelial, connective, muscular, and nervous. Epithelial tissue covers the body, lines all cavities, and composes the glands. Learning Objectives Key Points
Key Terms
Functions of the EpitheliumEpithelia tissue forms boundaries between different environments, and nearly all substances must pass through the epithelium. In its role as an interface tissue, epithelium accomplishes many functions, including:
Characteristics of Epithelial LayersEpithelial tissue is composed of cells laid out in sheets with strong cell-to-cell attachments. These protein connections hold the cells together to form a tightly connected layer that is avascular but innervated in nature. The epithelial cells are nourished by substances diffusing from blood vessels in the underlying connective tissue. One side of the epithelial cell is oriented towards the surface of the tissue, body cavity, or external environment and the other surface is joined to a basement membrane. The basement layer is non-cellular in nature and helps to cement the epithelial tissue to the underlying structures. Types of Epithelial TissueEpithelial tissues are identified by both the number of layers and the shape of the cells in the upper layers. There are eight basic types of epithelium: six of them are identified based on both the number of cells and their shape; two of them are named by the type of cell (squamous) found in them. Epithelial tissue is classified based on the number of cells, the shape of those cells, and the types of those cells.
What are the 7 characteristics of epithelial tissue?Characteristics of epithelial tissue include cell sheets and cellularity, cell junction, polarity, basement membrane, high regeneration, nerve innervation and lack of blood vessels.
What are the 4 properties of tissues?Overview. There are 4 basic types of tissue: connective tissue, epithelial tissue, muscle tissue, and nervous tissue. Connective tissue supports other tissues and binds them together (bone, blood, and lymph tissues). Epithelial tissue provides a covering (skin, the linings of the various passages inside the body).
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