Tissues: Epithelial Tissue

Chapter 2

Body TissuesBody Tissues

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Cells are specialized for particular functions

Tissues Groups of cells with similar structure and

function

Four primary types Epithelium Connective tissue Nervous tissue Muscle

Epithelial TissuesEpithelial Tissues

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Found in different areas Body coverings Body linings Glandular tissue

Functions Protection Absorption Filtration Secretion

Epithelium CharacteristicsEpithelium Characteristics

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Cells fit closely together

Tissue layer always has one free surface

The lower surface is bound by a basement membrane

Avascular (have no blood supply)

Regenerate easily if well nourished

Classification of EpitheliumClassification of Epithelium

Slide 3.44aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Number of cell layers

Simple – one layer

Stratified – more than one layer

Figure 3.16a

Classification of EpitheliumClassification of Epithelium

Slide 3.44bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Shape of cells

Squamous – flattened

Cuboidal – cube-shaped

Columnar – column-like

Figure 3.16b

Simple EpitheliumSimple Epithelium

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Simple squamous Single layer of flat

cells

Usually forms membranes

Lines body cavities

Lines lungs and capillaries Figure 3.17a

Simple EpitheliumSimple Epithelium

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Simple cuboidal Single layer of

cube-like cells

Common in glands and their ducts

Forms walls of kidney tubules

Covers the ovaries

Figure 3.17b

Simple EpitheliumSimple Epithelium

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Simple columnar

Single layer of tall cells

Often includes goblet cells, which produce mucus

Lines digestive tract

Figure 3.17c

Simple EpitheliumSimple Epithelium

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Pseudostratified Single layer, but

some cells are shorter than others

Often looks like a double cell layer

Sometimes ciliated, such as in the respiratory tract

May function in absorption or secretion

Figure 3.17d

Stratified EpitheliumStratified Epithelium

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Stratified squamous Cells at the free edge

are flattened

Found as a protective covering where friction is common

Locations Skin Mouth Esophagus Figure 3.17e

Stratified EpitheliumStratified Epithelium

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Stratified cuboidal Two layers of cuboidal cells

Stratified columnar Surface cells are columnar, cells

underneath vary in size and shape

Stratified cuboidal and columnar Rare in human body

Found mainly in ducts of large glands

Stratified EpitheliumStratified Epithelium

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Transitional epithelium

Shape of cells depends upon the amount of stretching

Lines organs of the urinary system

Figure 3.17f

Quick Quiz

What kind of epithelial tissue lines body cavities? Simple squamous

What kind of epithelial tissue is found in the mouth, skin, and esophagus? Stratified Squamous

If an epithelial tissue has many layers of squamous cells, how would we catagorize it? Stratified Squamous