Essay On Epithelia

Epithelia

Definition: The sheet of cells covering internal and external body surfaces. It isformed of cells joined by small amounts of cementing substances and is classified based on the number of layers and the shape of the cells.

Classification:

Types of Epithelial Tissue:

Simple epithelium:

• Squamous epithelium.

Squamous cells look like thin, flat plates. The shape of the nucleus is related to the cell form and help to know the type of epithelium. Squamous cells have flattened, elliptical nuclei due to the thin flattened form of the cell. They make the lining of cavities such as the mouth, blood vessels, heart and lungs and form the outer layers of the skin.

• Function: permits passage of materials

Transitional epithelium:

Transitional epithelium changes its display with stretching.

Function:

Stretches and allows distention of urinary organ.

Locations of epithelial tissues in the body:

Location of:

Transitional epithelium: urinary bladder.

Stratified columnar epithelium: male urethra.

Stratified cuboidal: largest ducts of glands.

Endothelium

The endothelium is a single layer of squamous cells that lines the inner wall of blood vessels and the lymphatics.

Mesothelium

Mesothelium is a single and thick cell layer that covers of our body cavities. General functions of epithelium

• Protection

Epithelial cells from the skin preserve the underlying tissue.

• Sensation

Sensory stimuli in specialised epithelial cells.

• Secretion

In glands, epithelial tissue secretes specific chemical substances like as enzymes, hormones and lubricating fluids.

• Absorption

Certain epithelial cells which are lining the small intestine absorb nutrients from the digestion of food.

• Excretion

Epithelial tissues in the kidney excrete waste products from the body and reabsorb important materials from the urine. Also sweat is excreted from the body by epithelial cells in the sweat glands.

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