Basics of Epithelial Tissues

Have you ever wondered what protects our body from the micro-organisms present in our surroundings?

It is the Epithelial tissue which forms a protective layer outside the body of internal organs and of blood vessels.

For example, external skin, the inner lining of the mouth, digestive tract are formed by epithelial tissue.

The epithelial cells are found in different shapes.

The types of epithelial tissue on basis of shape include squamous, columnar and cuboidal.

Squamous epithelium tissues are flat and scale-like cells.

They are found in the lining of the mouth, esophagus, the blood vessels, and alveoli of lungs.

Cuboidal Epithelium has cells that are cuboidal in shape with the same height and width.

They are commonly found in kidney tubules, small glands, and certain ducts.

Columnar Epithelium cells are cylindrical, taller and thin with less width.

If the columnar or cuboidal cells bear cilia on their free surface they are called ciliated epithelium

Their function is to move particles or mucus in a specific direction over the epithelium.

They are present in Bronchi, uterine tubes, and Uterus and the layers of the small intestine.

Some of the columnar or cuboidal cells get specialized for secretion and are called glandular epithelium. They are mainly of two types.

Unicellular Glandular epithelium consists of isolated glandular cells. E.g. Goblet cells of the alimentary canal

Multicellular glandular epithelium consists of a cluster of glandular cells. E.g. Salivary Gland, Acini in the pancreas, etc.

On the basis of the mode of pouring of their secretions, glands are divided into two categories namely exocrine and endocrine glands.

All these tissue cells are lined as single, double or multiple layers.

Based on the layers epithelial tissues are divided into Simple and Stratified.

When the epithelial cells are arranged in a single layer they are called simple epithelium.

When the epithelial cells are in more than one layer, they are called stratified epithelium.

Sometimes the epithelial cells are in a single layer But look like multiple layers.

These are called pseudostratified epithelial cells. The nuclei are unevenly placed here creating an illusion of multiple layers.

The epithelial cells perform various functions in the body.

They protect the body from outer damages and form lining in both outsides and inside the organs.

They protect the tissues from radiation, toxins and other external attacks from pathogens.

They are responsible for secreting hormones, mucus, and sweat in the ducts.

Revision

Epithelial tissues form a protective outer layer on the internal organs and blood vessels.

Epithelial tissues form a protective outer layer on the internal organs and blood vessels.

The epithelial cells are found in three different shapes- squamous, columnar and cuboidal.

Based on the number of layers they can be simple, stratified or pseudostratified.

Epithelial tissues protect the organs from damage.

The End