Give a brief description on different types of epithelial tissue
Answers
1)squamous :this is composed of a single layer of thin and flat plate like cell, it is found in the outer layer of the skin, it covers internal cavity and ducts.
2)cuboidal :It is a cube like cell that fit closely to each other and looks like square in section. it lies inside the kidney tube and silvery gland.
3)columnar :This tissue is generally composed of a single layer of column like cell, it is mostly found in lining of elementary column.
4)ciliated or glandular : gland develop from epithelial tissue which can secrete substance. it is found in sweat gland, mammary gland etc...
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Answer:
Epithelial Cells
It has a free surface that faces body fluid or external environment. The cells of epithelial tissue are compactly packed with little intercellular matrix and it lines the body parts.
The two types of epithelial tissues include this simple epithelial tissues and the compound epithelial tissue.
Simple Epithelial Tissues :
The simple epithelial tissues is composed of a single layer of cells and lines body cavities, ducts and tubes. Based on the structural modification of the the simple epithelial tissues they can be classified as squamous epithelium, cuboidal epithelium and columnar epithelium.
The squamous epithelium consists of single layer of flattened cells with irregular boundaries. They are found in the walls of blood vessels and alveoli and form a diffusion boundary.
The cuboidal epithelium is composed of cube like cells which are basically found in ducts of glands and tubular parts of nephron and function for secretion and absorption. The epithelium of proximal convoluted tubule of nephron has microvilli.
The columnar epithelium cells were tall and the nuclei was present at the base. They are found in the stomach and intestine lining. Some cells may have microvilli. They function for secretion and absorption.
The two types of modification of columnar and cuboidal cells include the ciliated epithelium and the glandular epithelium.
The ciliated epithelium include cells that bears cilias on their surface. They are present in inner surface of hollow organs like bronchioles and fallopian tube. They function to move particles or mucus in a specific direction.
The glandular epithelium function for secretion. The two types of this epithelium includes unicellular glandular epithelium the multicellular glandular epithelium.
The unicellular glandular epithelium consists of an isolated glandular cells like the goblet cells of the alimentary canal whereas the multicellular glandular epithelium consists of cluster of cells like the salivary gland.
The glandular epithelium can also be classified as exocrine glands and endocrine glands based on the mode of pouring the secretion.
Compound Epithelial Tissues :
The compound epithelial tissues consists of multi-layered cells which have a limited role in secretion and absorption.
They are found in the pharynx, inner lining of ducts of pancreas and salivary gland, skin and the surface of buccal cavity.
Their function is to protect against chemical and mechanical stresses.