Epithelial tissue Mrs. Dalia Kamal Eldien MSC in Microbiology Lecture NO 2.
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Transcript of Epithelial tissue Mrs. Dalia Kamal Eldien MSC in Microbiology Lecture NO 2.
Epithelial tissue
Mrs. Dalia Kamal Eldien
MSC in Microbiology Lecture NO 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
oDespite its complexity, the human body is composed of only four basic types of tissue:- Epithelial tissue Connective tissueMuscular tissue Nervous tissueoThese 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
DEFINITION:
Epithelium is a type of animal tissue made up of layers of
closely packed cells, with very little intercellular space.
Definition of Epithelium
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
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
Epithelial tissue rests on a basement membrane, a thin delicate membrane of protein fibers and glycosaminoglycans separating an epithelium from underlying tissue, which acts as a scaffolding on which epithelium can grow and regenerate after injuries
The basement membrane is composed of:
1) Basal lamina
2) Reticular lamina.
Basement membrane
1) Basal lamina:
The basal lamina is secreted by the epithelial cells.
Visible only with the electronic microscope
1) Reticular lamina:Is secreted by fibroblasts located in the underlying connective tissue.
Basement membrane
Functions of the Basement Membranes:
1) Provides support and attachment for the epithelial cells
2) Selective diffusion barrier
Basement membrane
Epithelium can be classified by:
1.Number of cell layers
2.Shape of uppermost cells
Classification of epithelial
Classification of epithelia
Simple epithelium:
1) One cell layer thick
2) All cells rest on the basement membrane
Stratified epithelium
3) More than one cell layer thick
4) Only the deepest layer of cells contact the basement
membrane
Classification of epithelia
Classification of epithelia
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.
Epithelial cells
First name of tissue indicates number of cell layers: Simple – one layer of cells Stratified – more than one layer of cells Last name of tissue describes shape of cells Squamous Cuboidal Columnar
Naming the epithelial tissue
SIMPLE EPITHELIUM:
1. Simple squamous epithelium
is one cell thick; that is, every cell is in direct contact with
the underlying basement membrane. In general, it is
found where absorption and filtration occur. The thinness
of the epithelial barrier facilitates these processes
Types of epithelial
Simple squamous epithelium
Simple squamous epithelium
SIMPLE SQUAMOUS EPITHELIUM
• LOCATION
• 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 epithelial
Simple cubiodal epithelial
SIMPLE CUBIODAL EPITHELIUM
LOCATION
1. In most of glands like salivary, mammary etc
2. In collecting ducts of kidneys
Simple cubiodal epithelial
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
Simple columnar epithelial
Simple columnar epithelial
SIMPLE COLUMNAR EPITHELIUM LOCATION
Mostly located in the lining of small intestine
Types of epithelial
STARTIFIED EPITHELIUM
1. Stratified squamous epithelium
2. Stratified cuboidal epithelium
3. Stratified columnar epithelium
OTHER TYPES
4. Pseudo stratified columnar epithelium
5. Transitional epithelium
Types of epithelial
STRATIFIED SQUAMOUS EPITHELIUM
LOCATION
• outer layers of skin, linings of oral cavity, throat, vagina, and anal canal
Types of epithelial
STRATIFIED SQUAMOUS EPITHELIUM
STRATIFIED SQUAMOUS EPITHELIUM
STRATIFIED CUBIODAL EPITHELIUM
LOCATION
Mostly located in the ducts of salivary , sweat and mammary glands
Types of epithelial cells
STRATIFIED CUBIODAL EPITHELIUM
Stratified columnar epithelium
LOCATION
Located in male urethra
Types of epithelial
Stratified columnar epithelium
Stratified columnar epithelium
PSEUDOSTRATIFIED COLUMNAR EPITHELIUMPseudo means (false)1. Appears stratified because nuclei are at 2 or more levels2. NOT stratified because all cells touch basement
membrane. It can be ciliated or non ciliated. LOCATIONoNon ciliated variety is located in the ducts of male reproductive systemoCiliated type is located in upper respiratory tract eg trachea.
Types of epithelial cells
PSEUDOSTRATIFIED COLUMNAR EPITHELIUM
\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
Types of epithelial cells
TRANSITIONAL EPITHELIUM
Types of epithelial cells
Classification of epithelial tissue
Home work
Describe the following• Squamous, Cuboidal and columnar
epithelium cells ???????• Write shortly on the classification of
epithelial cells ???????Why the transitional epithelium named
so ?????????