The document provides an overview of tissues, specifically focusing on epithelial tissue, its structure, function, and classification. It discusses the four main types of tissues—epithelial, connective, muscle, and nervous—and highlights the special properties of epithelial cells, including their polarity and regeneration capabilities. Additionally, it details various types of epithelial tissue, their functions, and glandular epithelium types.

1. Warm-Up
1. What is a tissue?
2. The study of tissues is called ______.
3. What are the 4 main types of tissues? (See
the intro to Chapter 4 in textbook)

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

3. Chapter 4

4.  Tissue: group of cells that are similar in
structure and function
 Histology: study of tissues
Types of Tissues:
1. Epithelium (covering)
2. Connective (support)
3. Muscle (movement)
4. 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:
1. Covering and lining epithelium
2. Glandular epithelium
 Function:
 Protection
 Absorption
 Filtration
 Secretion

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

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

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

14. Simple Epithelium
 Absorption, secretion, filtration
 Very thin

15. Simple Epithelium

16. 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

17. Simple Epithelium
 Simple cuboidal
 Secretion & absorption
 Lines ducts of glands (salivary), kidney tubules,
ovary surface

18. Simple Epithelium
 Simple columnar
 Absorption and secretion
 Lines digestive tract
 Microvilli, cilia
 Mucous membranes:
lubricating mucus

19. 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

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

21. Stratified Epithelium
 Stratified squamous
 Withstand abuse, friction
 Esophagus, mouth, outer portion of skin

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

23. Stratified Epithelium
 Stratified columnar
 Thick, waterproof layer
 Pharynx, male urethra, lining ducts

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

25. 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

26. Exocrine Glands
Unicellular Multicellular
 Mucus cells or goblet
cells
 Duct structure