Question

Write four types of epithelial tissues and give 1 functions each.​

Answer 1

Explanation:

Functions of epithelial cells include secretion, selective absorption, protection, transcellular transport, and sensing. Epithelial layers contain no blood vessels, so they must receive nourishment via diffusion of substances from the underlying connective tissue, through the basement membrane.

Answer 2

Epithelial tissues are of following types:

(1) Simple squamous epithelium

(2) Stratified squamous epithelium

(3) Columnar epithelium, and

(4) Cubodial epithelium.

These tissues differ in structure that correlate with their unique functions. For example, in cells lining blood vessels or lung alveoli, where transportation of substances occurs through a selectively permeable surface, there is a simple flat kind of epithelium. This is called the simple squamous epithelium. Simple squamous epithelial cells are extremely thin and flat and form a delicate lining. The skin. oesophagus and the lining of the mouth are also covered with squamous epithelium.

Skin epithelial cells are arranged in many layers to prevent wear and tear. Since. they are arranged in a pattern of layers, the epithelium is called stratified squamous epithelium.

Where absorption and secretion occur, as in the inner lining of the intestine. Tall epithelial cells are present. This columnar epithelium facilitates movement across the epithelial barrier. In the respiratory tract. the columnar epithelial tissue also has cilia. which are hair-like projections on the outer surfaces of epithelial cells. These cilia can move, and their movement pushes the mucus forward to clear it. This type of epithelium is thus ciliated columnar epithelium.

Cuboidal epithelium forms the lining of kidney tubules and ducts of salivary glands, where it helps in the filtration process.

Epithelial cells often acquire additional specialization as gland cells. which can secrete substances at the epithelial surface. Sometimes a portion of the epithelial tissue folds inward, and a multicellular gland is formed. This is glandular epithelium.