Introduction to Tissues: Types and Functions

1. Chapter 4, part 1 The Tissue Level of Organization

2. Learning Objectives • Identify the four major tissue types and describe their functions. • Describe the relationship between form and function for each tissue type. • Discuss the types and functions of epithelial tissues. • Compare the structure and function of connective tissues.

3. Learning Objectives • Explain the structure and function of the four types of membrane. • Describe the three types of muscle tissue and the structural features of each. • Discuss the basic structure and role of neural tissue.

4. SECTION 4-1Tissues of the Body: An Introduction

5. Tissues and tissue types • Tissues are: • Collections of specialized cells and cell products organized to perform a limited number of functions • Histology = study of tissues • The four tissue types are: • Epithelial • Connective • Muscular • Nervous

6. Epithelial tissue • Includes glands and epithelium • Glands are secretory • Is avascular • Forms a protective barrier that regulates permeability • Cells may show polarity

7. Functions of epithelium • Physical protection • Control permeability • Provide sensation • Produce specialized secretions

8. Specializations of epithelium • Perform secretory functions • Perform transport functions • Maintain physical integrity • Ciliated epithelia move materials across their surface

9. Figure 4.1 The Polarity of Epithelial Cells Figure 4.1

10. Maintaining the integrity of epithelium • Cells attach via cell adhesion molecules (CAM) • Cells attach at specialized cell junctions • Tight junctions • Desmosomes • Gap junctions

11. Figure 4.2 Intercellular connections PLAY Animation: Intercellular connections Figure 4.2

12. Structure of typical epithelium • Basal lamina attaches to underlying surface • Lamina lucida • Lamina densa • Germinative cells replace short-lived epithelial cells

13. Classification of epithelia • Number of cell layers • Simple • Stratified • Shape of apical surface cells • Squamous • Cuboidal • Columnar

14. Epithelial Tissues and their Classifications

15. Figure 4.3 Squamous Epithelia Figure 4.3

16. Squamous Epithelial Tissue—Dermis and Epidermis

17. Figure 4.4 Cuboidal Epithelia Figure 4.4a

18. Figure 4.4 Cuboidal Epithelia Figure 4.4b

19. Figure 4.4 Transitional Epithelium Figure 4.4c

20. Figure 4.5 Columnar Epithelia Figure 4.5a

21. Figure 4.5 Columnar Epithelia Figure 4.5b

22. Figure 4.5 Columnar Epithelia Figure 4.5c

23. Glandular epithelia • Exocrine glands • Secrete through ducts onto the surface of the gland • Endocrine glands • Release hormones into surrounding fluid

24. Glandular secretions can be: • Merocrine (product released through exocytosis) • Apocrine (involves the loss of both product and cytoplasm) • Holocrine (destroys the cell)

25. Figure 4.6 Mechanisms of Glandular Secretion Animation: Mechanisms of glandular secretion PLAY Figure 4.6

26. Glands • Unicellular • Individual secretory cells • Multicellular • Organs containing glandular epithelium • Classified according to structure

27. Figure 4.7 A Structural Classification of Exocrine Glands Figure 4.7