types of epithelial tissue and it's function.
Answers
Explanation:
Epithelial tissues are widespread throughout the body. They form the covering of all body surfaces, line body cavities and hollow organs, and are the major tissue in glands. They perform a variety of functions that include protection, secretion, absorption, excretion, filtration, diffusion, and sensory reception.
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Answer:
✯Epithelial Tissue Functions
—☆Protection:
As it covers the entire body surface, it is the first line of defence against any kind of mechanical injury, chemical exposure, excessive fluid loss and infections. Ciliary projections present in the nose or upper respiratory tract, trap the dust particles and prevent it from entering the body
—☆Absorption:
The epithelial lining of the digestive tract absorbs water and nutrients
—☆Exchange of substances:
Epithelial tissue regulates the exchange of substances between body and external environment as well as the internal exchange between different parts of the body. Everything that enters the body or enters the bloodstream by absorption has to cross the epithelial barrier
—☆Sensation:
Sensory receptors are present in the epithelial tissue of the nose, eyes and ears, taste bud, etc. that help in transmitting signals from the external stimuli to the brain
—☆Secretion:
Various glands made up of epithelial cells secrete hormones, enzymes, saliva, mucus, sweat, etc.
✯Types of Epithelial Tissue
There are three types of epithelial cells, which differ in their shape and function.
—☆Squamous
- thin and flat cells
—☆Cuboidal
- short cylindrical cells, which appear hexagonal in cross-section
—☆Columnar
- long or column-like cylindrical cells, which have nucleus present at the base
On the basis of the number of layers present, epithelial tissue is divided into the simple epithelium and stratified or compound epithelium
—☆Simple Epithelium
it is composed of one layer of a cell and mostly has a secretory or an absorptive function
—☆Compound (Stratified) Epithelium
it is made up of two or more than two layers of cells and mostly has a protective function
The glandular epithelium is made up of cuboidal or columnar cells. They are specialised for secretion.
Unicellular isolated glandular cells, e.g. goblet cells
Multicellular- a cluster of cells, e.g. salivary glands
The columnar or cuboidal epithelium may bear cilia and are referred to as ciliated epithelium. They help in the movement of mucus in a specified direction, e.g. fallopian tubes and bronchioles.
Explanation:
◉LET'S EXPLORE MORE
✯What Is Epithelial Tissue?
Epithelial tissue or epithelium forms the outer covering of the skin and also lines the body cavity. It forms the lining of respiratory, digestive, reproductive and excretory tracts. They perform various functions such as absorption, protection, sensation and secretion.
✯Structure of Epithelial Tissue
Epithelial tissue is formed from a tightly fitted continuous layer of cells. One surface of the epithelial tissue is exposed to either the external environment or the body fluid. The other surface is attached to tissue by a membrane, which consists of fibres and polysaccharides secreted by epithelial cells.
There is little intercellular material present between cells. There are specialised junctions present between the cells of the epithelium, that link individual cells.
—☆Tight junctions-
- prevent leakage across tissues
—☆Adhering junctions-
- keep the neighbouring tissues well cemented together
—☆Gap junctions-
- facilitate the movement of ions and molecules across the tissue
Epithelial cells form membranes. The epithelial membrane consists of a layer of epithelial tissue and has underlying connective tissue. There are two types of epithelial membranes, mucous membrane and serous membrane.
—☆Mucous membrane:
It is also known as mucosa. There are goblet cells present, which secrete mucus. The mucus helps in lubrication, protection and easy movement of materials. It prevents tissues from drying. It lines the body cavities such as respiratory and digestive tracts, which open outside the body.
—☆Serous membrane:
The serous membrane lines the body cavities, which do not open outside the body, such as the lining of the pleural cavity, pericardial membranes. These membranes secrete the fluid inside the cavity and are made up of simple squamous epithelium.
—☆Glands:
are made up of epithelial cells. There are two types of glands, exocrine and endocrine. Exocrine glands secrete their product into a duct, e.g. goblet cells, sweat glands. Endocrine glands are called ductless glands and they release their product directly into the blood or intestinal fluid, e.g. hormones.