Epithelial Tissue

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Overview

The tissue which covers the body surface, organs, ducts, blood vessels etc. is called epithelial tissue. This note provides us an information about epithelial tissue.
Epithelial Tissue

The tissue which covers the body surface, organs, ducts, blood vessels etc. is called an epithelial tissue. The main functions of epithelial tissues are as follows:

  1. They help in the exchange of materials from the surrounding environment.
  2. They help in the secretion of hormones and other required juices.
  3. They help in the absorption of digested food and water in the alimentary canal.

On the basis of form and structure, epithelial tissue is classified into following types:

  1. Pavement/Squamous epithelium
  2. Cubical epithelium
  3. Columnar epithelium
  4. Glandular epithelium
  5. Ciliated epithelium
  6. Stratified epithelium


Pavement/Squamous Epithelium

Squamous epithelium consists of a single layer of cells. The cells of this epithelium are thin, broad and flat which are arranged like the mosaic tiles on the floor. So, it is also called pavement tissue. It is found in the skin epidermis, lining of the mouth, body cavities, oesophagus and blood vessels. It helps in the protection, exchange of gases and ultra-filtration.

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Cubical Epithelium

Cubical Epithelium is also a single-layered epithelium tissue. It has equal height and width. It has spherical nucleus placed more or less in the centre. The cells are closely fitted together and lie on a basement membrane. It is found in the duct of sweat gland, liver, seminiferous tubule, uterus etc. It is actively involved in the conduction of secretary materials. It also helps in absorption and excretion.


Columnar Epithelium

Columnar Epithelium is made of the single layer of cells. The cells of this epithelium are elongated and also lie on the basement membrane. The nucleus is usually located at the base of the cell. The height of the cell exceeds its width. It is found in lining of the stomach, intestine, reproductive organs, urogenital organs, gall bladder, salivary gland etc. It main functions are absorption and secretion.


Glandular Epithelium

Glandular Epithelium is a single layered tissue. It is also modified the form of columnar epithelium. The cells of this epithelium are specialized for the secretion of chemical substances needed for different activities of metabolism. Liver, pancreas, mammary glands, sweat glands and mucous glands are the examples of such tissues. These cells secrete the hormone, enzymes, saliva, mucus, etc.


Ciliated Epithelium

Ciliated Epithelium is a single layered tissue. It is modified form of columnar or cubical epithelium. It has fine, hair-like processes called cilia at the free margin. It is found in lining of the uterine tubes, nasal passage and respiratory tract. In the uterine tubes, the cilia propel ova towards the uterus, and in the respiratory tract, it propels mucus towards the throat.


Stratified Epithelium

Stratified Epithelium is formed of many layers of cells. In the deepest layers, the cells are mainly columnar and, as they grow towards the surface they become flattened. The lowest layer is called germinal layer which produces new cells. They are also of different types and are mainly found in the nails, hair and conjunctiva of eyes and larynx. It prevents loss of water and protects from mechanical injury.

Things to remember
  • The tissue which covers the body surface, organs, ducts, blood vessels etc. is called epithelial tissue.
  • Squamous epithelium consists of a single layer of cells.
  • Cubical Epithelium is also a single-layered epithelium tissue.
  • The cells of this epithelium are specialized for the secretion of chemical substances needed for different activities of metabolism.
  • Ciliated Epithelium is modified form of columnar or cubical epithelium.
  • The cells of this epithelium are elongated and also lie on the basement membrane.
  • Stratified Epithelium is formed of many layers of cells.
  • It includes every relationship which established among the people.
  • There can be more than one community in a society. Community smaller than society.
  • It is a network of social relationships which cannot see or touched.
  • common interests and common objectives are not necessary for society.
Videos for Epithelial Tissue
Classification of Epithelia - Drawn & Defined
Epithelial Tissue
Questions and Answers

The tissue which covers the body surface, organs, ducts, blood vessels etc. is called epithelial tissue.

The main functions of epithelial tissues are as follows:

  1. They help in the exchange of materials from the surrounding environment.
  2. They help in the secretion of hormones and other required juices.
  3. They help in the absorption of digested food and water in the alimentary canal.

Epithelial tissue is classified into following types:

  1. Pavement/Squamous epithelium
  2. Cubical epithelium
  3. Columnar epithelium
  4. Glandular epithelium
  5. Ciliated epithelium
  6. Stratified epithelium

Squamous epithelium consists of a single layer of cells. The cells of this epithelium are thin, broad and flat which are arranged like the mosaic tiles on the floor. So, it is also called pavement tissue. It is found in the skin epidermis, lining of the mouth, body cavities, oesophagus and blood vessels. It helps in the protection, exchange of gases and ultra-filtration.

Cubical Epithelium is also a single-layered epithelium tissue. It has equal height and width. It has spherical nucleus placed more or less in the centre. The cells are closely fitted together and lie on a basement membrane. It is found in the duct of sweat gland, liver, seminiferous tubule, uterus etc. It is actively involved in the conduction of secretary materials. It also helps in absorption and excretion.

Columnar Epithelium is made of the single layer of cells. The cells of this epithelium are elongated and also lie on the basement membrane. The nucleus is usually located at the base of the cell. The height of the cell exceeds its width. It is found in lining of the stomach, intestine, reproductive organs, urogenital organs, gall bladder, salivary gland etc. It main functions are absorption and secretion.

Glandular Epithelium is a single layered tissue. It is also modified the form of columnar epithelium. The cells of this epithelium are specialized for the secretion of chemical substances needed for different activities of metabolism. Liver, pancreas, mammary glands, sweat glands and mucous glands are the examples of such tissues. These cells secrete the hormone, enzymes, saliva, mucus, etc.

Ciliated Epithelium is a single layered tissue. It is modified the form of columnar or cubical epithelium. It has fine, hair-like processes called cilia at the free margin. It is found in lining of the uterine tubes, nasal passage and respiratory tract. In the uterine tubes, the cilia propel ova towards the uterus, and in the respiratory tract, it propels mucus towards the throat.

Stratified Epithelium is formed of many layers of cells. In the deepest layers, the cells are mainly columnar and, as they grow towards the surface they become flattened. The lowest layer is called germinal layer which produces new cells. They are also of different types and are mainly found in the nails, hair and conjunctiva of eyes and larynx. It prevents loss of water and protects from mechanical injury.

Epithelial tissue is a thin layer of protective cells which covers the body and organs. It characteristics are as follows:
a) They are attached to the basement membrane.
b) They lack blood capillaries.
c) They may be simple or compound depending upon the thickness of their layers.
Columnar epithelium is found in the mucous layer of stomach, intestine, pharynx, larynx gull bladder, salivary glands and urinogenital organs.
Its main functions are:
i) Absorption of digested food
ii) Secretion
The structure and locations of given tissues are shown in the following table:
Tissue Structure Locations
i) Pavement epithelium Flat nucleated cell having single layer. External layer of skin, oesophagus, lungs, blood vessels and bowman’s capsule of kidney.
ii)Cubical epithelium Cubical cells having same dimensions on each side. In kidney tubules, lungs, ovary and many glands
iii) Columnar epithelium Elongated and placed by side like columns. Mucous layer of stomach, intestine, pharynx, larynx, gull bladder, salivary glands and urinogenital organs.
iv) Ciliated epithelium Fine, hairs like structure are found at free margin. In lining of uterine tubes, nasal passage and respiratory track.
v) Glandular epithelium Modified form of columnar epithelium. Liver, pancreas, mammary glands, sweat glands and mucous glands.
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