Question 1 What are epithelial tissues?
Question 2 What are the functions of epithelial tissues?
Question 3 What are the functions of squamous epithelial tissues?
Question 4 What are the functions of cuboidal epithelial tissues?
Question 5 What are the functions of columnar epithelial tissues?
Question 6 What are the functions of ciliated epithelial tissues?
Question 7 What is collagen?
Contents
Epithelial Tissue
It is the protective tissue of animal body. The cells are tightly packed form continuos sheet, very little or no intercellular spaces, covers most of the organs. They lie on a delicate non-cellular basement membrane which contain special form of matrix called collagen.
They may be simple (composed of single layer of cells) or stratified (made up of several layers of cells)
Functions of Epithelial Tissue
(1) They form the outer layer of skin. They protect underlying cells from drying, injury, chemical effects etc.
(2) Form lining of mouth and alimentary canal, protect these organs.
(3) Help in absorption of water and nutrients.
(4) It forms barrier to keep different body system separate.
(5) Form lining of blood vessels, alveoli, kidney tubules.
(6) They secrete a variety of substances such as sweat saliva, enzymes etc.
Four Types of Epithelial Tissue
(a) Squamous
It is made up of thin, irregular shaped cells which fit to form a compact tissue. It forms the lining of blood vessels, mouth, alveoli, nose, oesophagus, skin. It protects the parts of body from mechanical injury, entry of germs, chemicals, drying.
(b) Cuboidal
They are cube shaped cells found in kidney tubules, ducts of salivary glands. They act as gland cell i.e. secrete substances at the epithelial surface. Sometimes a portion of tissue folds inwards and a multicellular gland is formed. This is called glandular epithelium. It helps in the absorption, excretion and secretion, provides mechanical support.
(c) Columnar
Cells are taller than broader, nucleus is towards base. It forms lining of stomach, small intestine, colon, gall bladder. It helps in the absorption and secretion(mucus by goblet cell)
(d) Ciliated
Certain cuboidal or columnar cell have hair like projections on the outer surface called cilia. Such cells form ciliated epithelium. They are found in sperm ducts, trachea, bronchi, kidney tubules, fallopian tubes. The beating of the cilia moves solid particles in one direction through ducts.
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