1. Epithelial tissues

2. Epithelial functions
1) Protection:  covers body and lines all body cavities;  provides a protective shield for underlying tissues         (e.g.  epidermis) 2) Absorption:  in some parts of the body it takes in certain materials (e.g. digestive tract) 3) Secretion:  in some parts of the body epi. tissue is specialized to secrete certain products         E.g. small intestine:  some cells are specialized to secrete mucus 4) Excretion:  in the kidney cells rid the body of materials 5) Surface transport:  cilia on cells move mucus and particles up and out 6) Sensory functions:  Ex. taste buds in the mouth

3. Cell shapes
1) squamous:  square cells that are thin and flat 2) cuboidal:  small cubes in cross section 3) columnar:  tiny columns

4. Layers
1) simple:  one layer of cells 2) stratified:  cells arranged in two or more layers 3) pseudostratified:  falsely appear to be layered

5. Epithelial tissues Cover all body surfaces, and body organs
Epithelial tissues are avascular
ET have a free surface, exposed to the outside of the structure
Under side have a basement membrane, always near connective tissue, connective tissues are very vascular
Cancers of epithelial tissues are called carcinomas

6. Simple Squamous Epithelium
Location: Alveoli of lungs, walls of capillaries, and linings of blood vessels
Function: Diffusion, filtration, and osmosis

7. Simple Squamous 1000X

8. Simple Squamous

9. Simple squamous 400X
Alveoli of lungs

10. Our slides

11. Simple Cuboidal epithelium
Location: surface of ovaries, linings of kidney tubules, and various other glands
Function:Secretion and absorption

12. Simple Cuboidal 400X

13. More simple cuboidal 400X

14. Simple cuboidal 400X

15. Our slides

16. Simple Columnar Epithelium
Location: lining of digestive tract, lining of uterus
Function:Protection, secretion, and absorption
Goblet cells often present- Secrete mucus

17. Simple Columnar 400x

18. Simple columnar with Goblet cells 400x

19. Our slides

20. Psuedostratified Columnar Epithelium
Location: Lining of respiratory tract, and lining of various tubes of reproductive tract.
Function: Protection, secretion, and movement of sex cells

21. Pseudostratified Columnar 400X

22. Pseudostratified Columnar 400X

23. Trachea 400X

24. Our slides

25. Stratified Squamous Epithelium
Location:Outer layers of skin, linings of mouth cavity, and anal canal
Function: Protection
Keratinazation- cells become filled with Keratin
Keratin- protein found in skin that waterproofs skin

26. Stratified squamous 400X

27. Stratified squamous 400x

28. Stratified Squamous 400X

29. Our slides

30. Our slides

31. Our slides

32. Transitional Epithelium
Location: Lining of urinary bladder, passageways of urinary tract
Function: Distensibility and protection
Distensibility- ability to change shape

33. Transitional