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Tissues: Epithelial Tissue
Chapter 2
Body TissuesBody Tissues
Slide 3.41Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
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
Slide 3.42Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Found in different areas Body coverings Body linings Glandular tissue
Functions Protection Absorption Filtration Secretion
Epithelium CharacteristicsEpithelium Characteristics
Slide 3.43Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
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
Slide 3.45Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Simple squamous Single layer of flat
cells
Usually forms membranes
Lines body cavities
Lines lungs and capillaries Figure 3.17a
Simple EpitheliumSimple Epithelium
Slide 3.46Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
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
Slide 3.47Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Simple columnar
Single layer of tall cells
Often includes goblet cells, which produce mucus
Lines digestive tract
Figure 3.17c
Simple EpitheliumSimple Epithelium
Slide 3.48Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
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
Slide 3.49Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
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
Slide 3.50Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
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
Slide 3.51Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
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