1. Textus Epithelialis (ghufron_histo@yahoo.co.id). December 12,2008
Tissues are:
Collections of specialized cells and cell products organized to perform a limited number of functions
The four tissue types are:
Epithelial
Connective
Muscular
Nervous

2. Epithelial tissue Includes glands and epithelium Is avascular
Glands are secretory
Some characteristics:
Is avascular
Forms a protective barrier that regulates permeability
Cells may show polarity

3. Functions of epithelium
Physical protection
Control permeability
Provide sensation
Produce specialized secretions

4. The Polarity of Epithelial Cells
Figure 4.1

5. Connections: Cells attach via cell adhesion molecules (CAM)
Cells attach at specialized cell junctions
Tight junctions
Desmosomes
Gap junctions
List one function for each type of cell junction.

6. Figure 4.2

7. Structure of typical epithelium
Basal lamina attaches to underlying surface
Lamina lucida
Lamina densa
Germinative cells – Function?

8. Classification of epithelia
Number of cell layers
Simple
Stratified
Shape of apical surface cells
Squamous
Cuboidal
Columnar

9. Squamous Epithelia
Figure 4.3

10. Cuboidal Epithelia
Figure 4.4a

11. Cuboidal Epithelia
Figure 4.4b

12. Transitional Epithelium
Figure 4.4c

13. Columnar Epithelia
Figure 4.5a

14. Columnar Epithelia
Figure 4.5b

15. Columnar Epithelia
Figure 4.5c

16. Glandular epithelia Exocrine glands Endocrine glands
Secrete through ducts onto the surface of the gland
Endocrine glands
Release hormones into surrounding fluid

17. Glandular secretions can be:
Merocrine (product released through exocytosis)
Apocrine (involves the loss of both product and cytoplasm)
Holocrine (destroys the cell)

18. Mechanisms of Glandular Secretion
Figure 4.6