Epithelial tissues

Parakeratinized epithelium is sometimes found in the oral mucosa and in the upper regions of the esophagus. Gap junctions connect the cytoplasm of two cells and are made up of proteins called connexins six of which come together to make a connexion.

They attach the epithelial cell to the basement membrane. The cells fit closely together in tissues; providing a smooth, low-friction surface over which fluids can move easily. In general, epithelial tissues are classified by the number of their layers and by the shape and function of the cells.

Simple cuboidal epithelium commonly differentiates to form the secretory and duct portions of glands. Epithelial tissues help in elimination of waste. Ciliated pseudostratified epithelial cells have cilia. The cells here may possess microvilli for maximising the surface area for absorption and Epithelial tissues microvilli may form a brush border.

Eight types of epithelial tissue

Ciliated epithelium is found in the airways nose, bronchibut is also found in the uterus and Fallopian tubeswhere the cilia propel the ovum to the uterus.

It is sometimes called urothelium since it is almost exclusively found in the bladder, ureters and urethra. Most pseudostratified epithelia contain cilia on their apical surface and line the respiratory tract. While all animals can generally be considered to contain the four tissue types, the manifestation of these tissues can differ depending on the type of organism.

Columnar Columnar epithelial cells are elongated and column-shaped and have a height of at least four times their width. Animal tissues are grouped into four basic types: Specialized contacts— epithelial cells fit close together and form continuous sheets except in the case of glandular epithelia.

Epithelial Tissue

This tissue covers all organismal surfaces that come in contact with the external environment such as the skinthe airways, and the digestive tract. For example, Epithelial tissues origin of the cells comprising a particular tissue type may differ developmentally for different classifications of animals.

Non-ciliated epithelium can also possess microvilli. All epithelia is usually separated from underlying tissues by an extracellular fibrous basement membrane. Specialized squamous epithelium also forms the lining of cavities such as in blood vessels, as endothelium and in the pericardiumas mesothelium and in other body cavities.

Simple cuboidal epithelium— consists of a single layer of cells with the same height and width. However, other cellular features, such as cilia may also be described in the classification system.

When viewing pseudostratified epithelium it may look like there are several layers of cells, but this is not the case. Some tissues contain goblet cells and are referred to as simple glandular columnar epithelium.

The outer layer of the skin epidermis is keratinized contains keratin, a protective protein. For instance, in epithelia that absorb or secrete substances, the microvilli are extremely dense giving the cells a fuz zy appearance called a brush border.

Muscular tissue Main article: The basement membrane reinforces the epithelium and helps it resist stretching and tearing. Endothelium— provides a friction-reducing ling in lymphatic vessels and all hollow organs of the cardiovascular system heart, blood vessels, capillaries. Blood, bone, tendon, ligament, adipose and areolar tissues are examples of connective tissues.

The germinal epithelium that covers the female ovaryand the germinal epithelium that lines the walls of the seminferous tubules in the testes are also of the cuboidal type. Functions include absorption and secretion. Single-layered non-ciliated columnar epithelium tends to indicate an absorptive function.

This specialization makes the epithelium waterproof, so is found in the mammalian skin. Transitional epithelium— forms the lining of hollow urinary organs, which stretch as they fill with urine. The shape of the nucleus usually corresponds to the cell form and helps to identify the type of epithelium.

Tight junctions are a pair of trans-membrane protein fused on outer plasma membrane. Stratified columnar epithelium Stratified columnar epithelium— is also rare in the human body.


Other epithelial cells line the insides of the lungsthe gastrointestinal tractthe reproductive and urinary tracts, and make up the exocrine and endocrine glands. Classification of Epithelia Epithelium has two names.

Functions include secretion and absorption located in small ducts of glands and kidney tubules.Epithelial Tissue. Epithelial tissues are widespread throughout the body.

They form the covering of all body surfaces, line body cavities and. Epithelium (/ ˌ ɛ p ɪ ˈ θ iː l i ə m /) is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous mi-centre.comlial 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 epithelial tissues are formed by cells that cover the organ surfaces such as the surface of skin, the airways, the reproductive tract, and the inner lining of the digestive mi-centre.com cells comprising an epithelial layer are linked via semi-permeable, tight junctions; hence, this tissue provides a barrier between the external environment and the organ it.

The cells in epithelial tissue are very closely packed together and joined with little space between them. With its tightly packed structure, we would expect epithelial tissue to serve some type of barrier and protective function and that is certainly the case.

First name of tissue indicates number of cell layers. Simple—one layer of cells; Stratified—more than one layer of cells; Last name of tissue describes shape of cells. Characteristics of Epithelial Tissue. 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.

Epithelial tissues
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