write the functions and position of different types of epithelial tissues
Answers
Answer:
Epithelial Tissue
All layers and organs in the body are lined by a group of tissues called epithelial tissues which are commonly referred to as epithelium. They cover the surface of all internal as well as external organs. Epithelial tissue is highly permeable. Thus, it plays a significant role in the exchange of substances across the cells and helps in maintaining the osmoregulation. Depending on the number of layers of cells it is composed of, epithelium has been divided into simple epithelium and compound epithelium. The main functions of epithelial tissue are protection, secretion, absorption, and sensation.
Simple Epithelial Tissue
This type of epithelium is composed of a single layer of cells which mainly make up the linings of ducts, tubes and other cavities in the body.Based on the structure of the cell, the simple epithelial tissue is classified into three types viz.:
Squamous epithelium:
It is a simple single-layered epithelium.
Structurally, squamous epithelium is made up of flat cells with irregular boundaries.
It forms linings of blood vessels and alveoli.
Cuboidal epithelium:
The tissue is made of cube-shaped cells.
It forms the lining of kidney tubules and ducts of salivary glands.
Columnar epithelium:
It is composed of tall and slender, column-shaped
It forms the lining of stomach and intestine.
Epithelium
This article is about epithelium in animal anatomy. For the fungal structure of the same name, see Pileipellis.
Epithelium (/
ˌɛpɪˈθiːliəm
/)[1] is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. 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.
Epithelium
Types of epithelium
Pronunciation
epi- + thele + -ium
Identifiers
MeSH D004848
TH H2.00.02.0.00002
FMA 9639
Anatomical terms of microanatomy
[edit on Wikidata]
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), 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 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.[2][3] Cell junctions are well employed in epithelial tissues.
Classification
Summary showing different epithelial cells/tissues and their characteristics.
In general, epithelial tissues are classified by the number of their layers and by the shape and function of the cells.