Types Of Epithelial Tissue And Their Functions And Location Pdf
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Most epithelial tissue is described with two names. The first name describes the number of cell layers present and the second describes the shape of the cells. For example, simple squamous epithelial tissue describes a single layer of cells that are flat and scale-like in shape. Epithelial Tissue : There are three principal classifications associated with epithelial cells. Squamous epithelium has cells that are wider than they are tall.
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Describe the structural characteristics of the various epithelial tissues and how these characteristics enable their functions. Epithelial tissue primarily appears as large sheets of cells covering all surfaces of the body exposed to the external environment and lining internal body cavities. In addition, epithelial tissue is responsible for forming a majority of glandular tissue found in the human body. Epithelial tissue is derived from all three major embryonic layers. The epithelial tissue composing cutaneous membranes develops from the ectoderm.
An Atlas of Histology pp Cite as. They have a basement membrane, which separates the epithelial cells and the underlying connective tissue. They have a free, or apical, surface and a basal surface. The free surface is adjacent to the lumen; the basal surface rests on the basement membrane. Unable to display preview. Download preview PDF. Skip to main content.
Epithelial tissues are widespread throughout the body. They form the covering of all body surfaces, line body cavities and hollow organs, and are the major tissue in glands. They perform a variety of functions that include protection, secretion, absorption , excretion, filtration, diffusion , and sensory reception. The cells in epithelial tissue are tightly packed together with very little intercellular matrix. Because the tissues form coverings and linings, the cells have one free surface that is not in contact with other cells. Opposite the free surface, the cells are attached to underlying connective tissue by a non-cellular basement membrane.
If your institution subscribes to this resource, and you don't have a MyAccess Profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus. Please consult the latest official manual style if you have any questions regarding the format accuracy. Despite its complexity, the organs of the human body are composed of only four basic tissue types: epithelial, connective, muscular, and nervous tissues. Each tissue is an assemblage of similarly specialized cells united in performing a specific function. The basic tissues, each containing extracellular matrix ECM as well as cells, associate with one another in the variable proportions and morphologies characteristic of each organ. The main features of the basic tissue types are summarized in Table 4—1. Connective tissue is characterized by cells producing very abundant ECM; muscle tissue is composed of elongated cells specialized for contraction and movement; and nervous tissue is composed of cells with long, fine processes specialized to receive, generate, and transmit nerve impulses.
Epithelial tissue comprises one of the four basic tissue types. The others are connective tissue support cells, immune cells, blood cells , muscle tissue contractile cells , and nervous tissue. Organs represent various combinations of these four basic tissue types, which thus comprise the entire body. Each tissue type retains its fundamental character wherever it occurs. The boundary between you and your environment is marked by a continuous surface, or epithelium, of contiguous cells.
It is a thin, continuous, protective layer of cells. Epithelial tissues line the outer surfaces of organs and blood vessels throughout the body, as well as the inner surfaces of cavities in many internal organs. An example is the epidermis , the outermost layer of the skin. There are three principal shapes of epithelial cell: squamous, columnar, and cuboidal. These can be arranged in a single layer of cells as simple epithelium, either squamous, columnar, or cuboidal, or in layers of two or more cells deep as stratified layered , or compound , either squamous, columnar or cuboidal.