1. Warm-Up What is a tissue? The study of tissues is called ______.
What are the 4 main types of tissues?

2. Warm-Up 1. 2. 3. 4. What type of epithelial cell is shown below?
Simple Columnar Epithelium
Pseudostratified Columnar Epithelium 3. 4.
Simple Cuboidal Epithelium
Stratified Squamous Epithelium

3. Tissue: The Living Fabric

4. Tissue: group of cells that are similar in structure and function
Histology: study of tissues
Types of Tissues:
Epithelium (covering)
Connective (support)
Muscle (movement)
Nervous (control)

5. Preparing tissues for microscopy
Specimen is fixed (preserved)
Cut into thin sections (slices)
Stained with colored dyes

6. Part I: Epithelial Tissue

7. Epithelial Tissue “epithe” = laid on, covering Structure:
Covering and lining epithelium
Glandular epithelium
Function:
Protection
Absorption
Filtration
Secretion

8. Special Properties Polarity
Apical surface = exposed free surface or edge (some with microvilli, cilia)
Basal surface = lower, attached surface
Specialized contacts
Fits close together to form continuous sheets

9. Special Properties Supported by connective tissue
Rests on basement membrane
No blood supply (avascular)
Rely on diffusion and underlying connective tissue for food/O2
Regeneration – Replace lost cells

10. Classification Two names = (# cell layers) + (shape of cells)
Cell Layers: simple or stratified
Shapes: squamous, cuboidal, or columnar

14. Lumen: the opening of a tube, vessel or hollow organ, surrounded by epithelial tissue.

15. Simple Epithelium Absorption, secretion, filtration
Very thin – only one cell layer

16. Simple Epithelium
Lumen
Lumen
Lumen L

17. Simple Epithelium Simple squamous Filtration, rapid diffusion
Capillary walls, air sacs in lungs, kidney filtration
Serous membranes: slick layer lining ventral body cavity and its organs
Air sac

18. Simple Epithelium Simple cuboidal Secretion & absorption
Lines ducts of glands (salivary), kidney tubules, ovary surface
Lumen

19. Simple Epithelium Simple columnar Absorption and secretion
Lines digestive tract
Microvilli, cilia
Mucous membranes: lubricating mucus
Lumen

20. Simple Epithelium Pseudostratified columnar
Rests on basement membrane – false impression (pseudo) of being multi-layered
Secretes or absorbs
Respiratory tract – cilia propels mucus from lungs
Golbet Cells – secrete mucus
Lumen
Lumen
Goblet Cells

21. Stratified Epithelium
2+ layers, more durable
Main function = protect

22. Stratified Epithelium
Stratified squamous
Withstand abuse, friction
Esophagus, mouth, outer portion of skin

23. Stratified Epithelium
Stratified cuboidal
Usually 2 layers
Mainly in ducts of large glands (sweat, mammary, salivary)
Lumen
Lumen
Sweat Gland
Esophageal Gland

24. Stratified Epithelium
Stratified columnar
Thick, waterproof layer
Pharynx, male urethra, lining ducts
Lumen
Lumen

25. Transitional Epithelium
Able to change shape (cuboidal  squamous)
Lining of hollow urinary organs (bladder, ureter, urethra)
Stretches when filled with urine
Lumen

26. Glandular Epithelium Gland: make and secrete a particular product
2 Types:
Endocrine gland: produce hormones secreted into tissue fluid or bloodstream
Exocrine gland: secrete products into ducts  onto body surfaces or body cavities
Eg. mucous, sweat, oil, saliva, bile

27. Exocrine Glands Unicellular Multicellular Mucus cells or goblet cells
Duct structure