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

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.

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.

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)

1.Number of cell layers 2.Shape of uppermost cells

Number of cell layers One layer of cells (Simple epithelium) More than one layer (Stratified epithelium)

SHAPE OF CELLS FLAT (SQUAMOUS) CUBE LIKE (CUBIODAL) COLUMN LIKE (COLUMNAR)

EPITHELIUM 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.

EPITHELIUM cell

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

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

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

3.Simple columnar epithelium. found in areas with extremely high secretive (as in wall of the stomach), or 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).

SIMPLE COLUMNAR EPITHELIUM LOCATION Mostly located in the lining of small intestine

STRATIFIED SQUAMOUS EPITHELIUM LOCATION outer layers of skin, linings of oral cavity, throat, vagina, and anal canal outer layers of skin, linings of oral cavity, throat, vagina, and anal canal

STRATIFIED SQUAMOUS EPITHELIUM

STRATIFIED CUBIODAL EPITHELIUM LOCATION Mostly located in the ducts of salivary, sweat and mammary glands

STRATIFIED CUBIODAL EPITHELIUM

Stratified columnar epithelium LOCATION Located in male urethra

Stratified columnar epithelium

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.

PSEUDOSTRATIFIED COLUMNAR EPITHELIUM

CILIATED PSEUDOSTRATIFIED COLUMNAR EPITHELIUM

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

TRANSITIONAL EPITHELIUM

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 ?????????