1. Epithelial tissue Mrs. Dalia Kamal Eldien MSC in Microbiology Lecture NO 2

2.  To explain What is epithelium.  What are the types of epithelium and their functions.  What are the locations of different epithelium in human body. Objectives

3. o Despite its complexity, the human body is composed of only four basic types of tissue:-  Epithelial tissue  Connective tissue  Muscular tissue  Nervous tissue o These tissues, which all contain cells and molecules of the extracellular matrix (ECM), exist in association with one another and in variable proportions and morphologies, forming the different organs of the body. Introduction

5. 1)Covers the internal and external surfaces of body. 2)Forms the linings of body cavities and vessels. 3) Have no blood supply (AVASCULAR) 4)Can easily regenerate if well nourished. Characteristic of epithelial

6. 1)Covering, lining, and protecting surfaces (eg, skin) 2)Absorption (eg, the intestines) 3)Filtration (eg, the blood capillaries of kidney) 4)Secretion (eg, the epithelial cells of glands) Functions

7. Basement membrane

10. 1.Number of cell layers 2.Shape of uppermost cells Classification of epithelial

11. Number of cell layers One layer of cells (Simple epithelium) More than one layer (Stratified epithelium) Classification of epithelia

13. SHAPE OF CELLS FLAT (SQUAMOUS) CUBE LIKE (CUBIODAL) COLUMN LIKE (COLUMNAR) Classification of epithelia

14. Epithelial cells o There are three principal morphologies associated with epithelial cells:  Squamous epithelium has cells that are wider than they are tall (flat and scale-like), Nucleus flat, central.  Cuboidal epithelium has cells whose height and width are approximately the same (cube shaped), Nucleus spherical.  Columnar epithelium has cells taller than they are wide (column-shaped), Nucleus oblong basal.

15. Epithelial cells

16. Naming the epithelial tissue

17. Types of epithelial

18. Simple squamous epithelium

20. SIMPLE SQUAMOUS EPITHELIUM LOCATION Endothelium: heart, blood vessels, lymphatic. Mesothelium : Pericardium, pleura,peritoneum. others ： alveoli of the lungs, in kidney tubules etc

21. 2.Simple cubiodal epithelium These cells may have secretory, absorptive, or excretory functions. examples include small collecting ducts of kidney, pancreas and salivary gland.

22. Simple cubiodal epithelial

24. SIMPLE CUBIODAL EPITHELIUM LOCATION 1.In most of glands like salivary, mammary etc 2.In collecting ducts of kidneys Simple cubiodal epithelial

25. 3.Simple columnar epithelium. found in areas with extremely high secretive (as in wall of the stomach), or high absorptive (as in small intestine) areas. they possess cellular extensions (e.g. microvilli in the small intestine, or cilia found almost exclusively in the female reproductive tract). Types of epithelial tissue

26. Simple columnar epithelial

28. SIMPLE COLUMNAR EPITHELIUM LOCATION Mostly located in the lining of small intestine Types of epithelial

30. STRATIFIED SQUAMOUS EPITHELIUM LOCATION outer layers of skin, linings of oral cavity, throat, vagina, and anal canalouter layers of skin, linings of oral cavity, throat, vagina, and anal canal Types of epithelial

31. STRATIFIED SQUAMOUS EPITHELIUM

33. STRATIFIED CUBIODAL EPITHELIUM LOCATION Mostly located in the ducts of salivary, sweat and mammary glands Types of epithelial cells

34. STRATIFIED CUBIODAL EPITHELIUM

36. Stratified columnar epithelium LOCATION Located in male urethra Types of epithelial

37. Stratified columnar epithelium

39. PSEUDOSTRATIFIED COLUMNAR EPITHELIUM Pseudo means (false) 1. Appears stratified because nuclei are at 2 or more levels 2.NOT stratified because all cells touch basement membrane.  It can be ciliated or non ciliated. LOCATION o Non ciliated variety is located in the ducts of male reproductive system o Ciliated type is located in upper respiratory tract eg trachea. Types of epithelial cells

40. PSEUDOSTRATIFIED COLUMNAR EPITHELIUM

41. \PSEUDOSTRATIFIED COLUMNAR EPITHELIUM

42. CILIATED PSEUDOSTRATIFIED COLUMNAR EPITHELIUM

43. TRANSITIONAL EPITHELIUM The transitional epithelium is named so because it can transit between two states. 1. In empty bladder cells are umbrella shaped and show many layers. 2.In full bladder cells become flattened and show less layers. LOCATION Located in the inner lining of urinary bladder Types of epithelial cells

44. TRANSITIONAL EPITHELIUM Types of epithelial cells

47. Home work Describe the following Describe the following ???????Squamous, Cuboidal and columnar epithelium cells ??????? Write shortly on the classification of epithelial cells ???????Write shortly on the classification of epithelial cells ??????? Why ????????? Why the transitional epithelium named so ?????????