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Epithelial TissuePage 78 - 81

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Characteristics Fit closely together to form continuous

sheets. Has an apical surface which is a free

surface that is exposed to the body’s exterior or to the cavity of an internal organ.

Has a basement membrane which is where the lower surface is attached.

No blood supply or avascular. Can regenerate themselves easily.

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Classification of Epithelium

Arrangement Simple – one layer

of cells Stratified – more

than one cell layer

Shape Squamous –

flattened Cuboidal – cube-

shaped like dice Columnar –

shaped like columns

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Types of Simple Epithelial Cells

Simple squamous Simple cuboidal Simple columnar Pseudostratified columnar

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Simple Squamous Epithelium Single layer of thin squamous cells Lines air sacs of lungs, walls of

capillaries and forms the serous membranes

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Squamous Epithelium

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Simple Cuboidal Epithelium Single layer of cuboidal cells Found in salivary glands and pancreas

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Simple Cuboidal Epithelium

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Simple Columnar Epithelium Single layer of tall cells Goblet cells (produce

a lubricating mucus)are often present

Lines entire digestive tract from stomach to anus

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Simple Columnar Epithelium

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Pseudostratified Columnar Single layer of columnar cell with

different heights giving it a multiple layer look.

Goble cell often present Cells found in the respiratory tract have

cilia (ciliated).

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Pseudostratified Columnar

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Types of Stratified Epithelia Stratified squamous Stratified cuboidal transitional

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Stratified Squamous Epithelium Several layers of squamous cells with

either cuboidal or columnar cells near the basement membrane.

Found in the esophagus, mouth, and outer portion of the skin.

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Stratified Squamous Epithelium

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Stratified Cuboidal & Stratified Columnar Epithelia Rare Found mainly in the ducts of large

glands

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Stratified Cuboidal & Stratified Columnar Epithelia

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Transitional Epithelium Highly modified, stratified squamous

epithelium found in the bladder, ureters, and part of urethra.

Cells change shape to adapt to considerable stretching.

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Transitional Epithelia

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Glandular Epithelium Endocrine glands

Has no connection to the surface – ductless glands

Ex. Thyroid, adrenal, pituitary Exocrine glands

Secretions empty through the ducts to the epithelial surface

Ex. Sweat and oil glands (external surface), liver and pancreas (internal surface)