1. Tissue: The Living Fabric P A R T A

2. Tissues Groups of cells similar in structure and function The four types of tissues 1. Epithelial 2. Connective 3. Muscle 4. Nerve

3. Epithelial Tissue 1. Cellularity – composed almost entirely of cells 2. Special contacts – form continuous sheets 3. Polarity – apical and basal surfaces 4. Supported by connective tissue –basal lamina 5. Avascular but innervated – contains no blood vessels but supplied by nerve fibers 6. Regenerative – rapidly replaces lost cells

4. Classification of Epithelia: Number of Layers Simple, stratified, or pseudostratified Figure 4.1a

5. Classification of Epithelia: Shape Squamous, cuboidal, or columnar Figure 4.1b

6. Epithelia: Simple Squamous Single layer of flattened cells Disc-shaped nuclei Functions Diffusion and filtration Endothelium = low-friction lining Present in the kidney glomeruli, lining of heart, blood vessels, lymphatic vessels, and serosae

7. Epithelia: Simple Squamous Figure 4.2a

8. Epithelia: Simple Cuboidal Single layer of cube-like cells Large, spherical nuclei Function in secretion and absorption Present in kidney tubules, ducts and glands, and ovary surface

9. Epithelia: Simple Cuboidal Figure 4.2b

10. Epithelia: Simple Columnar Single layer of tall cells Oval nuclei May contain cilia and goblet cells Function in absorption and secretion Nonciliated type lines digestive tract and gallbladder Ciliated type lines small bronchi and uterine tubes

11. Epithelia: Simple Columnar Figure 4.2c

12. Epithelia: Pseudostratified Columnar Single layer of cells with different heights Nuclei are seen at different layers Function in secretion and propulsion of mucus Present in the male sperm-carrying ducts (nonciliated) and trachea (ciliated)

13. Epithelia: Pseudostratified Columnar Figure 4.2d

14. Epithelia: Stratified Squamous Several layers of cells Function in protection of areas subjected to abrasion Forms the external part of the skin’s epidermis (keratinized cells), and linings of the esophagus, mouth, and vagina (nonkeratinized cells)

15. Epithelia: Stratified Squamous Figure 4.2e

16. Epithelia: Stratified Cuboidal and Columnar Stratified cuboidal Rare Found in some sweat and mammary glands Two layers Stratified columnar Rare Found in the pharynx, male urethra, and ducts

17. Epithelia: Transitional Several cell layers Basal cells are cuboidal, surface cells are rounded Lines the urinary bladder, ureters, and urethra Stretches to permit the distension of the urinary bladder

18. Epithelia: Transitional Figure 4.2f

19. Epithelia: Glandular Gland = one or more cells that makes and secretes fluid Classified by: 1. Site of product release – endocrine or exocrine 2. Number of cells – unicellular or multicellular

20. Endocrine Glands Ductless glands that produce hormones Hormones travel directly to the bloodstream Examples include Pancreas Pituitary gland Hypothalamus

21. Exocrine Glands More numerous than endocrine glands Secretory unit (acinus) secretes products into ducts which travel to body surfaces or into body cavities Examples include Mucous glands Sweat glands Oil glands Salivary glands

22. Unicellular and Multicellular Exocrine Glands Unicellular = goblet cell Multicellular exocrine glands have ducts and secretory units (acini) Classified according to: Simple or compound duct type Structure of their secretory units Tubular Alveolar Tubuloalveolar

23. Goblet Cell Figure 4.3b

24. Structural Classification of Multicellular Exocrine Glands Figure 4.4a–d

25. Structural Classification of Multicellular Exocrine Glands Figure 4.4e–g