1. Epithelia

2. 1.Cell: the basic structure of human cell 2.Tissue: consists of cells and intercellular substance 3.Organ: consists of different tissues which have related function 4.System: consists of different organs which have related function Human organization

3. Human Tissues Epithelia Connective tissue Muscle Tissue Nervous tissue

4. 一、 General characteristics and classification of epithelia （一） General characteristics of epithelia 1. cells arranged intensively;small quantity of intercellular substance. 2. cells have polarity. 3. no blood vessels. 4. Function: ： Protection, secretion, and absorption,etc.

5. （二） Classification of Epithelia Epithelia mainly classified into 2 sorts: Covering epithelia ： C ells arranged like membrane Localization: covering the outer surface of the body and the inner surface of the cavities,Sacs or ducts within the body. Function: Protection. Glandular epithelia ： Function - Secretion

6. 二、 covering epithelia Principles of the classification ： Layers of the cells ： simple epithelia stratified epithelia Shape of the cells ： Squamous epithelia Cuboidal epithelia Columnar epithelia

7. Simple squamous epithelia Simple cuboidal epitheliaSimple columnar epithelia Stratified squamous epitheliaTransitional epithelia Pseudostratified ciliated columnar epithelia

8. 1. simple squamous epithelia Description: Single layer of flat cells with disc- shaped central nuclei. Top view: Polygonal, central nuclei Side view: Squamous, central nuclei Function: Allows passage of material by diffusion & filtration and reduces friction by providing a smooth surface & secreting lubricating serous fluid.

9. Simple squamous epithelia endothelium : heart, blood vessles lymphatics mesothelium : Pericardium, pleura peritoneum others ： alveoli of the lungs, glomeruli in the kidney, etc Localization

10. simple squamous epithelium

11. (1) endothelium

12. endothelium

13. (2) mesothelium

14. (3) others

15. 2. simple cuboidal epithelium Description: Single layer of cubelike cells with large, spherical central nuclei. Function: Function in secretion and absorption. Locations: (1) In the secretory portions of many glands : thyroid, mammary, and salivary. (2) In the kidney tubules

16. simple cuboidal epithelium

19. 3. simple columnar epithelium Description: Single layer of columnar cells with oval nuclei ; often have an apical border of microvilli; Many contain goblet cells (mucus-secreting unicellular glands). Function: absorption of nutrients; secretion of mucus & enzymes. Locations: digestive tract,etc.

20. simple columnar epithelium

23. 4. pseudostratified ciliated columnar epithelium Description: single layer of cells of differing heights, but some don't reach the free surface. Nuclei are seen at many different levels. They contain goblet cells and cilia. Function: secretion & propulsion of mucus Locations: l the trachea & most of the upper respiratory tract.

24. pseudostratified ciliated columnar epithelium

27. 5. stratified squamous epithelium Description: multiple layers of cells. Surface cells are flattened. Basal cells: cuboidal or columnar; active in mitosis and produce the cells of the more superficial layers. Function: resists abrasion and acts as a barrier, Retards water loss through skin. Locations: skin, mouth, vagina, esophagus ， etc.

28. Stratified Squamous epithelium keratinized stratified squamous epithelium: skin Surface is covered with layers of compact dead cells without nuclei (and full of keratin) nonkeratinized stratified squamous epithelium: esophagus,oral cavity

29. stratified squamous epithelium

30. keratinized stratified squamous epithelium

31. nonkeratinized stratified squamous epithelium

32. 7. transitional epithelium Description: multiple layers of cells. Surface cells are dome-shaped. Middle layers : cells are polyhedral Basal cells: cuboidal or columnar. Locations: renal pelvis and calyces,the ureter, the urinary bladder,etc.

33. transitional epithelium

36. 6.stratified columnar epithelium

37. （一） surface of epithelia 1. microvillus 2. cilium 三、 special structure of each side

38. 1.Microvillus function ： enlarge the area of the surface

39. 2.Cilium Function ： regularly swing

40. 1. tight junction 2. intermediate junction 3. desmosome 4. gap junction （二） side face of epithelia

42. （三 ) Underside of the epithelia 1. basement membrane 2. plasma membrane infolding 3. hemidesmosome

43. 1.basement membrane Function: support,connect,etc.

44. 2.plasma membrane infolding function ： enlarge the area of the underside

45. 3.Hemidesmosome Function:fixing