1. Tissues
Epithelial Tissue

2. Tissues
A group of similar cells that work together to perform a specific function.
Four main types of tissues:
Epithelial
Connective
Muscular
Nervous
All cells present in a tissue are surrounded by/bathed in an extracellular matrix (ECM)
ECM-nonliving material (no cells), usually fluid (but can be solid), produced by the cells it surrounds.

3. Epithelial Tissue
Widespread through out the body, present in every body system.
Very diverse cell types compose it (9 types)
Avascular-no blood vessels present
Very little ECM present
Are usually able to repair themselves and/or regenerate through the life span
Located on the outside of the body, on the outside of the organs, lining hollow spaces inside organs and lining body cavities.
Function to provide sensation, protect, absorb substances, secrete substances (produce) and excrete substances (eliminate).
Common for intercellular connections to be present.

4. Intercellular Connections
Many epithelial tissues have specialized connections between the individual cells.
Connections are protein structures (3 Types)
Desmosomes: Anchor adjacent cells to one another.
Help keep epithelial tissue in tact.

5. 2. Tight junctions: fuse cell membranes at intermittent spots
Allow for more rapid diffusion of substances between cells.

6. 3. Gap junctions: tubular channels between cells
Also allow for more rapid diffusion of substances.

8. Distinct features of ALL epithelial tissues…
Basement Membrane: nonliving material that anchors the epithelial tissue to the underlying tissue Free surface/lumen
Epithelial cells
Basement Membrane
Underlying tissue

9. 2. Free surface: Open space on the side/edge of the ET.
Also called the lumen when it is inside organs/cavities

10. Types of Epithelial Nine types
Classified according to the shape of cell and the number of cell layers present in the tissue.
Name consists of two parts, the Part1-Indicates the number of cell layers
Part 2-Indicates the shape of the cells.

11. 1 Cell Layer: Simple Simple Squamous Simple Cuboidal Simple Columnar
Squamous: flat/squashed
Simple Cuboidal
Cuboidal: cubes
Simple Columnar
Columnar: columns
Could have microvilli or cilia on free
surface.
Goblet cells-are secreting cells

12. 2 or More Cell Layers: Stratified
Stratified Squamous
Squamous: squashed cells at free surface
Stratified Cuboidal
Cuboidal: many times only 2-3 layers thick
Stratified Columnar
No cilia or microvilli

13. Pseudostratified Columnar Epithelium
Abbrev. Pseudostartfied
Looks like more than one cell layer but it’s not
Stratified Transitional Epithelium
A type of stratified epithelium
Tissue stretches & cells at free surface change shape.
Distended= stretched tissue

14. Glandular Epithelium Classified because of function
Could be simple cuboidal, simple columnar, stratified cuboidal, stratified columnar or pseudostratified.
Specialized to secrete
Are endocrine glands or exocrine glands

15. What type of ET do you see?
Simple cuboidal

16. What type of ET do you see?
Stratified squamous

17. What type of ET do you see?
Simple columnar (ciliated)

18. What type of ET do you see?
Psuedostratified

19. What type of ET do you see?
Simple cuboidal

20. What type of ET do you see?
Simple Squamous

21. What type of ET do you see?
Transitional