Describe the structure and functions of various types of epithelial tissues
Answers
Answer:
Explanation: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. In some tissues, a layer of columnar cells may appear to be stratified due to the placement of the nuclei. This sort of tissue is called a pseudostratified. All glands are made up of epithelial cells. Functions of epithelial cells include secretion, selective absorption, protection, transcellular transport, and sensing.
Epithelial layers contain no blood vessels, so they must receive nourishment via diffusion of substances from the underlying connective tissue, through the basement membrane. Cell junctions are well employed in epithelial tissues,In general, epithelial tissues are classified by the number of their layers and by the shape and function of the cells.[2][4][5]
The three principal shapes associated with epithelial cells are squamous, cuboidal, and columnar.
Squamous epithelium has cells that are wider than their height (flat and scale-like). This is found as the lining of the mouth, oesophagus, and including blood vessels and in the alveoli of the lungs.
Cuboidal epithelium has cells whose height and width are approximately the same (cube shaped).
Columnar epithelium has cells taller than they are wide (column-shaped). Columnar epithelium can be further classified into ciliated columnar epithelium and glandular columnar epithelium.
By layer, epithelium is classed as either simple epithelium, only one cell thick (unilayered), or stratified epithelium having two or more cells in thickness, or multi-layered – as stratified squamous epithelium, stratified cuboidal epithelium, and stratified columnar epithelium, and both types of layering can be made up of any of the cell shapes However, when taller simple columnar epithelial cells are viewed in cross section showing several nuclei appearing at different heights, they can be confused with stratified epithelia. This kind of epithelium is therefore described as pseudostratified columnar epithelium.
Transitional epithelium has cells that can change from squamous to cuboidal, depending on the amount of tension on the epithelium.
I WOULD GO ON BUT THIS SEEMS LIKE A LOT TO TAKE IN