1. Good fences make good neighbors
Epithelial Tissues
Good fences make good neighbors

2. Epithelial Tissues
Cover ALL body surfaces, line organs, are major tissues of glands
1 side is exposed to open space, underside is attached to connective tissue by a thin, non-cellular basement membrane
Lack blood vessels, fed by diffusion from well vascularized connective tissues

3. More Epithelial Characteristics
Reproduce rapidly
Tightly packed
Good barriers: Skin, lining of mouth
Involved in secretion, absorption, excretion, sensory reception

4. Simple Squamous Epithelium
1 layer, thin, flattened
Broad, thin nucleus
Things pass through these easily: diffusion, filtration
Easily damaged
Found in: Alveoli, capillary walls, blood, lymph vessel lining, body cavity lining

5. Simple Squamous Epithelium

6. Simple Squamous Epithelium

7. Simple Cuboidal Epithelium
1 layer, cube shaped cells
Central, spherical nucleus
Covers ovaries, kidney tubules, glandular ducts (salivary, thyroid, pancreas, liver)
Secretion (in glands)
Absorption (kidneys)

8. Simple Cuboidal Epithelium

9. Simple Cuboidal Epithelium
                                                                                                    

10. Simple Columnar Epithelium
Elongated, 1 layer
Nuclei located near basement membrane on about the same level
Line uterus, most organs of digestive tract
Thick, protective of underlying structures
Secretes digestive fluids, absorbs nutrients
Can have microvilli
Can have goblet cells embedded, secrete mucus onto surface

11. Simple Columnar Epithelium

12. Simple Columnar Epithelium

13. Pseudostratified Columnar Epithelium
Appear layered, but not: Nuclei stacked at different levels
Often found with cilia, goblet cells scattered throughout
Lines respiratory, reproductive systems

14. Pseudostratified Columnar Epithelium

15. Stratified Squamous Epithelium
Thick, composed of several layers
Cell division at deeper layers, older cells get pushed up/out
In epidermis, lines mouth, throat, vagina, anus
In epidermis, keratin (a tough protein) causes old cells to harden and die, forming a protective layer.
Keritinization causes cells to become tough, dry
This keeps water in, chemicals, microbes out

16. Stratified Squamous Epithelium

17. Stratified Cuboidal Epithelium
Have 2-3 layers which line a lumen
Line larger ducts like in mammary glands, sweat glands, salivary glands, pancreas
Also found lining ovarian follicles, seminiferous tubules

18. Stratified Cuboidal Epithelium

19. Stratified Columnar Epithelium
Layers of cells
Superficial (shallow) cells are elongated, deeper cells (basal layers) are cuboidal
Found in male urethra, vas deferens, parts of pharynx

20. Stratified Columnar Epithelium

21. Stratified Columnar Epithelium vs Stratified Cuboidal Epithelium

22. Transitional Epithelium
Changes in response to tension: stretchy
Inner lining of bladder, lining of urinary passages
Several layers of cuboidal cells
Flatten when stretched, cuboidal when relaxed
Keeps urine in

23. Transitional Epithelium

24. Transitional Epithelium

25. Glandular Epithelium Specialized to make and secrete a product
Found mostly within cuboidal and columnar epithelia
Exocrine glands secrete into ducts.
Merocrine glands: watery, protein-rich secretions
Serous Cells: secretions are watery, enzyme filled (serous fluid): found in glands in body cavities
Mucous cells: secrete thick mucous containing mucin, a glycoprotein: In digestive, respiratory systems
Holocrine Glands: cell bursts during secretion
Apocrine glands: cell loses some cytoplasm during secretion
Endocrine glands secrete into blood

26. Glandular Epithelium