General function of epithelial tissue
Key Terms simple columnar: A columnar epithelium that is uni-layered. The cell nucleus is large, spherical and is in the center of the cell.
Cuboidal epithelial tissue
All cells are in contact with the basement membrane. These cells are found in areas with high secretory function such as the wall of the stomach , or absorptive areas as in small intestine. Pseudostratified Epithelium: Pseudostratified epithelium appears to be stratified, but is not. Other ciliated cells are found in the fallopian tubes , the uterus and central canal of the spinal cord. Pseudostratified epithelium can also possess fine hair-like extensions of their apical luminal membrane called cilia. Other areas include the airways, the digestive tract, as well as the urinary and reproductive systems, all of which are lined by an epithelium. Ciliated pseudostratified epithelial cells have cilia. Key Terms simple columnar: A columnar epithelium that is uni-layered. In the respiratory tract , the wafting effect produced causes mucus secreted locally by the goblet cells to lubricate and to trap pathogens and particles to flow in that direction typically out of the body. Transitional Epithelia Transitional epithelia are found in tissues that stretch and it can appear to be stratified cuboidal when the tissue is not stretched, or stratified squamous when the organ is distended and the tissue stretches. Stratified cuboidal epithelium and stratified columnar epithelium can also be found in certain glands and ducts, but are uncommon in the human body. Columnar - Analogous to the shape of bricks on an end.
This membrane is a mixture of carbohydrates and proteins secreted by the epithelial and connective tissue cells. Epithelial cells may be squamous, cuboidal, or columnar in shape and may be arranged in single or multiple layers.
The bottom surface of endothelium is attached to a basement membrane, while the free surface is usually exposed to fluid.
Squamous epithelial tissue
Transitional describes a form of specialized stratified epithelium in which the shape of the cells can vary. They consist of protein complexes and provide contact between neighbouring cells, between a cell and the extracellular matrix , or they build up the paracellular barrier of epithelia and control the paracellular transport. In simple cuboidal epithelium, the nucleus of the box-like cells appears round and is generally located near the center of the cell. Many epithelial tissues are capable of rapidly replacing damaged and dead cells. The endothelial cells in the brain that form the blood-brain barrier, for instance, are highly selective and allow only certain substances to move across the endothelium. Epithelial Tissue Function Epithelial tissue covers the outside of the body and lines organs, vessels blood and lymph , and cavities. The epithelium of the small intestine releases digestive enzymes, for example. In general, it is found where absorption and filtration occur. Stratified epithelia can be columnar, cuboidal, or squamous type. As such, the passage of substances in the CNS is very restrictive. Stratified columnar epithelium is rare but is found in lobar ducts in the salivary glands , the eye , pharynx and sex organs. Type Description Squamous Squamous cells have the appearance of thin, flat plates that can look polygonal when viewed from above. For example, the skin is composed of a layer of epithelial tissue epidermis that is supported by a layer of connective tissue.
Stratified epithelia can be columnar, cuboidal, or squamous type. Pseudostratified columnar epithelium lines portions of the respiratory tract and some of the tubes of the male reproductive tract. They beat in unison and move fluids as well as trapped particles.
This consists of a layer of cells resting on at least one other layer of epithelial cells which can be squamous, cuboidal, or columnar. These cells are found in areas with high secretory function such as the wall of the stomachor absorptive areas as in small intestine.
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