Epithelial tissues

Epithelial functions 1) Protection:  covers body and lines all body cavities;  provides a protective shield for underlying tissues         (e.g.  epidermis) 2) Absorption:  in some parts of the body it takes in certain materials (e.g. digestive tract) 3) Secretion:  in some parts of the body epi. tissue is specialized to secrete certain products         E.g. small intestine:  some cells are specialized to secrete mucus 4) Excretion:  in the kidney cells rid the body of materials 5) Surface transport:  cilia on cells move mucus and particles up and out 6) Sensory functions:  Ex. taste buds in the mouth

Cell shapes 1) squamous:  square cells that are thin and flat 2) cuboidal:  small cubes in cross section 3) columnar:  tiny columns

Layers 1) simple:  one layer of cells 2) stratified:  cells arranged in two or more layers 3) pseudostratified:  falsely appear to be layered

Epithelial tissues Cover all body surfaces, and body organs Epithelial tissues are avascular ET have a free surface, exposed to the outside of the structure Under side have a basement membrane, always near connective tissue, connective tissues are very vascular Cancers of epithelial tissues are called carcinomas

Simple Squamous Epithelium Location: Alveoli of lungs, walls of capillaries, and linings of blood vessels Function: Diffusion, filtration, and osmosis

Simple Squamous 1000X

Simple Squamous

Simple squamous 400X Alveoli of lungs

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Simple Cuboidal epithelium Location: surface of ovaries, linings of kidney tubules, and various other glands Function:Secretion and absorption

Simple Cuboidal 400X

More simple cuboidal 400X

Simple cuboidal 400X

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Simple Columnar Epithelium Location: lining of digestive tract, lining of uterus Function:Protection, secretion, and absorption Goblet cells often present- Secrete mucus

Simple Columnar 400x

Simple columnar with Goblet cells 400x

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Psuedostratified Columnar Epithelium Location: Lining of respiratory tract, and lining of various tubes of reproductive tract. Function: Protection, secretion, and movement of sex cells

Pseudostratified Columnar 400X

Pseudostratified Columnar 400X

Trachea 400X

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Stratified Squamous Epithelium Location:Outer layers of skin, linings of mouth cavity, and anal canal Function: Protection Keratinazation- cells become filled with Keratin Keratin- protein found in skin that waterproofs skin

Stratified squamous 400X

Stratified squamous 400x

Stratified Squamous 400X

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Transitional Epithelium Location: Lining of urinary bladder, passageways of urinary tract Function: Distensibility and protection Distensibility- ability to change shape

Transitional