1. Identify the type of borders found on epithelial tissue.
Bell Work:
Identify the type of borders found on epithelial tissue.

2. Epithelial Function Location: Functions: Covers body Surfaces
Lines body cavities
Forms glands
Functions:
Secretion
Selective absorption
Protection
Transcellular support
Detection of sensation

3. Function Secretion Selective Absorption Protection
When a cell produces substances and releases those substances into the environment.
Ie. Digestive tract has high secretion
Selective Absorption
Epithelial tissue is in direct contact with the outer environment so it selects what materials come into and out of the cell
Protection
Tissue in contact with the external environment has to have a protective function to protect internal tissue
Ie. Skin

4. Function Transcellular Transport Detection of Sensation
Able to help substances travel through a certain distance
Detection of Sensation
Associated with nerve cells because epithelium can be found on the external part of the body; nerve cells receive stimuli

5. Epithelial Features Cells are usually joined together
Little or no intercellular material
Don’t have a lot of extracellular material around them

6. Classifications of Epithelia
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Classifications of Epithelia
First the name of tissue indicates # of layers (3 types)
1. Simple – one layer of cells (extends from basement membrane to the apical surface)
2. Stratified – more than one layer of cells

7. Classification of Epithelia
3. Pseudostratified- tissue appears to be stratified, but all cells contact basement membrane so it is in fact simple

8. Classifications of Epithelia
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Classifications of Epithelia
Last name of tissue describes shape of cells (3 types)
1. Squamous – cells wider than tall (plate or “scale” like)
2. Cuboidal – cells are as wide as tall, as in cubes
3. Columnar – cells are taller than they are wide, like columns

9. 5/23/2019
Naming Epithelia
Naming the epithelia includes the layers (first) and the shape of the cells (second)
i.e. stratified cuboidal epithelium
The name may also include any accessory structures
Goblet cells, cilia, keratin, etc.
Special epithelial tissues (don’t follow naming convention)
Psuedostratified
Transitional

11. How do you go about naming epithelial tissue?
Do Now:
How do you go about naming epithelial tissue?

12. Naming Practice!

15. Objectives:
Describe the functions and locations of simple epithelial tissue.
Describe the functions and locations of stratified epithelial tissue.

16. Simple Squamous Epithelium
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Simple Squamous Epithelium
Description
Single layer of flat cells with disc-shaped nuclei
Special types
Endothelium (inner covering)
Slick lining of hollow vessels (blood & lymph)
Mesothelium (middle covering)
Lines abdominal, pleural, and pericardial cavities
Covers visceral (internal) organs of those cavities (ie. heart, stomach, lung, etc.)
Peritoneal (abdomen), pleural (lung), pericardial (heart)
Visceral organs (heart, lungs, intestine, pancreas, spleen, stomach etc)

17. Simple Squamous Epithelium
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Simple Squamous Epithelium
Function:
Passage of materials by passive diffusion and filtration
Secretes lubricating substances reducing friction in mesothelial membranes
Location:
Alveoli of lungs
Lining of heart, blood and lymphatic vessels
Lining of ventral body cavity (pericardium, pleural and abdominopelvic cavities)
Ventral cavity (thoracic and abdominal cavities)

18. Simple Squamous Epithelium
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Small, flat cells arranged around large, empty circles (air sacs). May be confused with Adipose Tissue, but note the multiple cells and nuclei (arrows).
Simple squamous lining the walls of the capillary

19. Simple Cuboidal Epithelium
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Simple Cuboidal Epithelium
Description
Single layer of cube-like cells with large, spherical central nuclei
Function
Secretion and absorption
Location
Kidney, secretory portions of small glands (ie. saliva and thyroid), ovary surface

20. Simple Cuboidal Epithelium
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Simple Cuboidal Epithelium
Squarish cells with round nuclei in a single row (arrows), usually arranged in a circle (tubule).

21. Simple Columnar Epithelium
Description
Single layer of column-shaped (rectangular) cells with oval nuclei
Some have cilia at their apical surface
May contain goblet cells (secrete mucus)
Function
Absorption; secretion of mucus, enzymes, and other substances
Ciliated type propels mucus or reproductive cells by ciliary action
Scaffolding

22. Simple Columnar Epithelium
Location
Non-ciliated form
Lines stomach, small and large intestine and gallbladder
Ciliated form
Lines bronchioles (in lungs), uterine (fallopian) tubes, and uterus
Tall rectangular cells, with single, neat row of oval nuclei, usually more towards the base (in the bracketed row, the base is towards the top), leaving an apical region of nucleus-free cytoplasm. Note also goblet cells, found only here and in Pseudostratified Columnar Epithelium.

23. Do Now:
Identify a location where simple squamous, cuboidal or columnar tissue is found?

24. Stratified Epithelia Layers: contain two or more layers of cells
Regeneration: from Basal membrane
Function: protection
Naming: according to the shape of cells at apical layer

25. Stratified Squamous Epithelium
Description
Many layers of cells – squamous in shape
Deeper layers of cells appear cuboidal or columnar
Thickest epithelial tissue – adapted for protection

26. Stratified Squamous Epithelium
Specific types
Keratinized – contain the protective protein keratin
Surface cells are dead and full of keratin
Non-keratinized – forms moist lining of body openings
Surface cells are living
Function
Protects underlying tissues in areas subject to abrasion
Location
Keratinized – forms epidermis (top layer of skin)
Non-keratinized – forms lining of esophagus, mouth, and vagina

27. Stratified Squamous Epithelium
Many layers (6 or more) of small, flattened cells. The only other epithelial tissue with so many layers is transitional (below), but note that stratified squamous epithelium typically has a more evenly contoured surface; with the uppermost layers of cells flattened.
Non-keratinized vs. Keratinized

28. Stratified Cuboidal Epithelium
Description
Generally two layers of cube-shaped cells
Function
Protection
Location
Forms largest ducts of sweat glands
Forms ducts of mammary glands and salivary glands

29. Stratified Columnar Epithelium
Description
several layers; basal cells usually cuboidal; superficial cells elongated
Function
protection and secretion
Location
Rare tissue type
Found in male urethra and ducts, pharynx, and anus

30. Do Now:
Identify a location where stratified squamous, cuboidal or columnar tissue is found?

31. Pseudostratified Columnar Epithelium
Description
All cells originate at basement membrane
Only tall cells reach the apical surface
May contain goblet cells and bear cilia
Nuclei lie at varying heights within cells
Gives false impression of stratification
Function
secretion of mucus; propulsion of mucus by cilia

32. Pseudostratified Columnar Epithelium
Locations
Non-ciliated type
Ducts of male reproductive tubes
Ducts of large glands
Ciliated variety
Lines trachea and most of upper respiratory tract
Tall rectangular cells, with multiple irregular rows of nuclei (bracketed; compare to simple columnar, above). Note also goblet cells, found only here and in Simple Columnar Epithelium.

33. Transitional Epithelium
Description
Basal cells usually cuboidal or columnar
Superficial cells dome-shaped or squamous
Function
stretches and permits distension of urinary bladder
Location
Lines ureters, urinary bladder and part of urethra

34. Transitional Epithelium
Relaxed state
Stretched state
Numerous layers of cells of varying and often irregular shape, though generally not squamous (when unstretched as in the slides). Surface of tissue is folded (inside of ureter) or bumpy appearing (urinary bladder).

36. Do Now:
Name three types of tissue, what they look at and a place where they can be found.

37. Glandular Epithelium
Ducts carry products of exocrine glands to epithelial surface
Include the following diverse glands
Mucus-secreting glands
Sweat and oil glands
Salivary glands
Liver and pancreas
May be: unicellular or multicellular

38. Unicellular Exocrine Glands (The Goblet Cell)
Goblet cells produce mucin
Mucin + water  mucus
Protects and lubricates many internal body surfaces

39. Types of Multicellular Exocrine Glands

40. Do Now:
What are the two types of stratified squamous epithelial? Where can they be found?

41. Do Now:
Where can simple cuboidal and stratified cuboidal be found? What is the difference in the function of each?