Structural Organisation in Animals

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Squamous epithelium:

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Single thin layer of flattened cells with irregular boundaries.

Found in the walls of blood vessels and lung alveoli.

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Functions: Form a diffusion boundary.

Cuboidal (cubical) epithelium:

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Composed of cube-like cells.

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Found in ducts of glands and tubular parts of nephrons.

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Functions: Secretion and absorption.

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The epithelium of proximal convoluted tubule (PCT) of nephron in

the kidney has microvilli.

Columnar epithelium:

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Composed of tall and slender cells.

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Their nuclei are located at the base.

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Free surface may have microvilli.

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Found in the lining of stomach and intestine. - Functions:

Secretion and absorption.

MØDÏFÏÇÅTÏØÑ ØF ÇØLÜMÑÅR ØR ÇÜBØÏDÅL ÇËLLS

Ciliated Epithelium:

Cells bearing cilia on their free surface.

Present in the inner surface of hollow organs like bronchioles and fallopian

tubes.

Functions: To move particles or mucus in a specific direction over the

epithelium.

Glandular epithelium; (a) Unicellular (b) Multicellular

unicellular

gland

Multicelluar

gland

(a)

(b)

Glandular Epithelium:

Some of the columnar or cuboidal cells get specialised for secretion are

called glandular epithelium.