explain about stratified epithelial tissue in 100 words
Answers
Explanation:
A stratified epithelium consists of several stacked layers of cells. This epithelium protects against physical and chemical wear and tear. The stratified epithelium is named by the shape of the most apical layer of cells, closest to the free space. Stratified squamous epithelium is the most common type of stratified epithelium in the human body. The apical cells are squamous, whereas the basal layer contains either columnar or cuboidal cells. The top layer may be covered with dead cells filled with keratin. Mammalian skin is an example of this dry, keratinized, stratified squamous epithelium. The lining of the mouth cavity is an example of an unkeratinized, stratified squamous epithelium. Stratified cuboidal epithelium and stratified columnar epithelium can also be found in certain glands and ducts, but are uncommon in the human body.
Another kind of stratified epithelium is transitional epithelium, so-called because of the gradual changes in the shapes of the apical cells as the bladder fills with urine. It is found only in the urinary system, specifically the ureters and urinary bladder. When the bladder is empty, this epithelium is convoluted and has cuboidal apical cells with convex, umbrella shaped, apical surfaces. As the bladder fills with urine, this epithelium loses its convolutions and the apical cells transition from cuboidal to squamous. It appears thicker and more multi-layered when the bladder is empty, and more stretched out and less stratified when the bladder is full and distended. Figure 4 summarizes the different categories of epithelial cell tissue cells.
A stratified epithelium is a type of epithelial tissue that is composed of more than one layer of epithelial cells. The basal layer is the only one that is in contact with the basal lamina. This layer is also the one that undergoes mitotic division producinh cells in the upper layers.
The stratified epithelium is found in the skin wherein the apical layer becomes heavily keratinized before dying, and is also continuously shed as squames. Stratified epithelia usually have a mechanical or protective role.
The stratified epithelium may be categorized based on the type of cells that makes it up. In particular, it may be squamous (flat-like), cuboidal (cube-like), or columnar (column-like)