Question

4 types of epithelial tissue are?

Answer 1

ANSWER- Epithelial tissue is a type of tissue which generally lines the organs i.e. it forms the outer lining of organs and is also present in the inner cavities of many organs.

Functions of epithelial tissue- Epithelial tissue is generally involved in protection, absorption, secretion and reception of stimuli.

Following are the types of epithelial tissue-

• Squamous epithelial tissue- It is a type of epithelial tissue in which the cells of epithelial tissue are thin and flattened. They look like thin scales and their nucleus is also flattened and horizontal.

It is further of two types-

• Simple squamous epithelial tissue- In simple squamous epithelial tissue, single layer of epithelial cells is present.  
• This type of tissue is mainly present in air sacs of lungs and it also forms the lining of blood vessels, lymphatic vessels and heart.
• Function of simple squamous epithelial tissue is to allow the movement of substances by the process of diffusion based on their concentration.

• Stratified squamous epithelial tissue- In stratified squamous epithelial tissue, more than one layer of epithelial cells is present.
• This type of tissue is mainly present in the lining of mouth, oesophagus and vagina.
• Function of stratified squamous epithelial tissue is to provide protection mainly against abrasion which can occur due to movement of food through mouth and oesophagus.

• Cuboidal epithelial tissue- It is a type of epithelial tissue in which the cells are of cube like or box like. Their cells look like small boxes and their nucleus is circular in shape and is present at the centre of the cell.

It is further of two types-

• Simple cuboidal epithelial tissue- In simple cuboidal epithelial tissue, single layer of epithelial cells is present.
• This type of tissue is mainly present in ducts and tubules.
• Function of simple cuboidal epithelial tissue is secretion and absorption of various substances.

• Stratified cuboidal epithelial tissue- In stratified cuboidal epithelial tissue, more than one layer of cuboidal epithelial cells is present.
• This tissue is mainly present in glands like salivary glands, sweat glands etc.
• Function of stratified cuboidal epithelial tissue is to provide protection to the tissue where it is present.

• Columnar epithelial tissue- It is a type of epithelial tissue in which the cells are of column like tall in shape. Their cells look like column and nucleus is long and present at the base of the cell.

It is further of three types-

• Simple columnar epithelial tissue- In simple columnar epithelial tissue, single layer of epithelial cells are present. This tissue have cilia on their surface present at the upper side of each cell.
• This tissue is mainly present in lungs ( bronchi) and digestive tract and urinary tract.
• Function of simple columnar epithelial tissue is absorption and secretion of various substances like mucus.

• Stratified columnar epithelial tissue- In stratified columnar epithelial tissue, more than one layer of cells is present.
• This tissue is mainly present in ducts and male urethra.
• Function of stratified columnar epithelial tissue is to provide protection.

• Pseudo stratified columnar epithelial tissue- In pseudo stratified columnar epithelial tissue, more than one layer of cells is present but the cells in irregular shape and the nucleus is also present at different positions in cell. It also have cilia on its surface
• This type of tissue is mainly present in respiratory tract and trachea.
• Function of pseudo stratified columnar epithelial tissue is secretion of mucus and cilia present on its surface helps to move the mucus in respiratory tract.

• Transitional epithelial tissue- It is a type of epithelial tissue in which the cells are of irregular shape and can also change their shape. This tissue is made up of more than one layer of cells.
• This tissue is mainly present in urinary tract ( mainly in urinary bladder and ureters).
• Function of transitional epithelial tissue is to allow the movement of urinary bladder when it gets filled with urine and when the urinary bladder gets empty.