Class 9 – Epithelial Tissue

Epithelial tissue covers the whole surface of the body.
Epithelial tissues are made up of cells that are closely packed and are composed of one or more layers.
This tissue is specialised to form the covering of all internal and external body surfaces.
Epithelial tissue that occurs on surfaces on the interior of the body is known as endothelium.
It acts as a barrier to keep different body parts separate.
Anything that enters the body has to cross any one of the above mentioned epithelial tissues.

Cells are flat and thin.
Consist of single layer of flat cells in contact with the basal lamina.
The skin that protects our body is made up of squamous epithelium. As they are arranged in many layers they are called as stratified squamous epithelium.
They are found where rapid diffusion is required.
They are found in Capillaries (blood capillaries), glomerulus (part of excretory system).
Present in: esophagus, lining of buccal cavity.

These are cube shaped cells.
Nucleus is located at the centre.
The cells of cuboidal epithelium perform the function of secretion and absorption.
This epithelial tissue fold inward and form a Multicellular gland called GLANDULAR EPITHELIUM.
Found in: lining of kidney tubules, surface of ovaries, linings of nephrons, duct of salivary glands.

COLUMNAR EPITHELIAL TISSUE

They are pillar like or rod shaped.
When these tissues bear cilia on them they are known as CILIATED COLUMNAR EPITHELIAL tissues.
Cilia are hair like outgrowth of small size which helps in passage of the substance from one part to other.
Present in: inner lining of intestine, stomach, parts of respiratory and reproductive as well as digestive system.

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