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Epithelial Tissue

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Tissue
Group of similar cells and their intercellular substance; similar origin in embryo; function together to perform specialized activity.
Epithelial (Classification & Function)
Cover body surfaces; lines body cavities & ducts; form glands.
Epithelial tissues consist of...
Largely or entirely of closely packed cells with little or no intercellular material between adjacent cells.
Epithelial tissues are arranged in...
Continuous sheets - nerves may extend through sheets, but blood vessels do not (avascular).
Epithelial tissues overlies and...
Adheres firmly to basement membrance (CT).
Apical
Free Surface
Basal
Attached Surface
Arrangement of Layers
Simple, Stratified, & Pseudostratified
Simple
Single layer; absorption & filtration; areas of minimal wear & tear.
Stratified
Several layers; stacked; areas of high degree of wear & tear.
Pseudostratified
One layer; some layers do not reach surface; multi-layered (stratified) appearance; columnar epithelial tissue.
Cell Shapes
Squamous, cuboidal, columnar, & transitional.
Squamous
Flattened, scale-like.
Cuboidal
Hexagons (sometimes); cube shaped in cross section.
Columnar
Tall, cylindrical.
Transitional
Distension (expansion); combination of shapes.
Simple Squamous ET
Lines blood vessels & air sacs; serous membranes.
Simple Cuboidal ET
Lines kidney tubes & ducts of glands.
Cilitated Simple Stratified Columnar ET
Upper respiratory tract; fallopian tubes.
Non-ciliated Simple Columnar ET
G.I. Tract.
Keratinized Stratified Squamous ET
Epidermis (skin).
Non-Keratinized Stratified Squamous ET
Lining of mouth, esophogus, vagina.
Transitional ET
Urinary bladder, ureters, urethra
Ciliated Psedostratified Columnar ET
Eustachian Tube
Non-Ciliated Psedostratified Columnar ET
Lines larger ducts of glands, male urethra.
Exocrine Glandular ET
Oil glands & sweat glands.
Endocrine Glandular ET
Secretes hormones; pituitary gland, thyroid gland, parathyroid glands, thymus gland, pineal gland.