1. Chapter 3: Epithelial Tissues
Pages 87-92

2. Epithelial Tissues Locations: Functions: Body coverings Body linings
Glandular tissue
Functions:
Protection
Absorption
Filtration
Secretion
© 2015 Pearson Education, Inc.

3. Epithelium Characteristics
Cells fit closely together and often form sheets
The apical surface is the free surface of the tissue
The unattached surface
Can be exposed to exterior or cavity of an organ
The lower surface of the epithelium (the basal lamina) rests on a basement membrane
Consists of reticular connective tissue
secures upper layers
© 2015 Pearson Education, Inc.

4. Epithelium Characteristics
Avascular (no blood supply)
Relies on circulatory system to obtain food and oxygen
Surrounding connective tissues supply via diffusion from nearby capillaries
Regenerate easily if well nourished (through normal cell division)
Cells on exterior of the skin are exposed to friction and other hostile substances and are sloughed off

5. Classification of Epithelia
Two name system:
First name = # of layers
Second name = shape of cells
Named using number of cell layers:
Simple—one layer
Absorption/secretion/filtration are main functions
Stratified—more than one layer
Ideal for protection
Often found where there is friction or abuse; durable
© 2015 Pearson Education, Inc.

6. Figure 3.17a Classification and functions of epithelia.
Apical surface
Basal surface
Simple
Apical surface
Basal surface
Stratified
(a) Classification based on number of cell layers

7. Epithelial shapes Names using shape of cells Squamous Cuboidal
Flattened, like fish scales
Cuboidal
Cube-shaped, like dice
Columnar
Column-like
© 2015 Pearson Education, Inc.

8. Figure 3.17b Classification and functions of epithelia.
Squamous
Cuboidal
Columnar
(b) Classification based on cell shape

9. Figure 3.17c Classification and functions of epithelia.
Number of layers
One layer: simple epithelial tissues
More than one layer: stratified epithelial tissues
Cell shape
Squamous
Diffusion and filtration Secretion in serous membranes
Protection
Cuboidal
Secretion and absorption; ciliated types propel mucus or reproductive cells
Protection; these tissue types are rare in humans
Columnar
Secretion and absorption; ciliated types propel mucus or reproductive cells
Transitional
Protection; stretching to accommodate distension of urinary structures
(c) Function of epithelial tissue related to tissue type
Remember these general characteristics and you will be able to classify each type a lot easier !!

10. Pseudostratified Columnar
Single layer
some cells are shorter than others, giving a false (pseudo) impression of stratification
© 2015 Pearson Education, Inc.

11. Pseudo- stratified epithelial layer
Figure 3.18d Types of epithelia and their common locations in the body.
Cilia
Pseudo- stratified epithelial layer
Pseudo- stratified epithelial layer
Basement membrane
Basement membrane
Connective tissue
Photomicrograph: Pseudostratified ciliated columnar epithelium lining the human trachea (560×).
(d) Diagram: Pseudostratified (ciliated) columnar

12. Transitional Epithelium
Unique because of its ability to become temporarily modified in arrangement and shape
modified stratified squamous epithelium
Can stretch and rebound
Locations: urinary system organs
© 2015 Pearson Education, Inc.

13. Transi- tional epithelium
Figure 3.18f Types of epithelia and their common locations in the body.
Basement membrane
Transi- tional epithelium
Transitional epithelium
Basement membrane
Connective tissue
Photomicrograph: Transitional epithelium lining of the bladder, relaxed state (270×); surface rounded cells flatten and elongate when the bladder fills with urine.
(f) Diagram: Transitional

14. Glandular Epithelium Two major gland types: Endocrine gland
Ductless; secretions diffuse into blood vessels
All secretions are hormones
Examples include thyroid, adrenals, and pituitary
Exocrine gland
Secretions empty through ducts to the epithelial surface
Include sweat and oil glands, liver (bile duct), and pancreas (digestive enzymes), mammary glands (milk)
Includes both internal and external glands
© 2015 Pearson Education, Inc.