MINISTRY OF DEFENCE

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  MINISTRY OF DEFENCE. Establishment Of National University In Islamabad Total position. 29 Domicile , All over Pakistan    Qualification  intermediate to bachelor positions . Project Engineer(Civil) account Officer  supervisor assistant office boy     How to apply.   Apply online through the link https://www.fgei-cg.gov.pk/nup-rec.php   Last date to apply  02 April 2023. No TA/DA Fo Interview 
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Epithelial Tissue

Tissue

 group of cells similar in structure origin and function.
Term Tissue was given by French anatomist and physiologists Bichat,term tissue was already given by N.Grew with plant anatomy.
Study of tissue is called Histology or microscopic anatomy.
Fther of Histology Bichat.

Epithelium 



origin:
Ectoderm,Endoderm and mesodermal.
Definition:
 It is defined as a collection of closely opposed cells with a Samal amount of intracellular matrix.
The layer of cells rest upon a non cellular basement membrane. in basement membrane 2 layers are present.
upper is basal lamina secreted by epithelial layer and  formed of glycoprotein and mucopolysaccharides which are secreted by epithelial cells.
lower is reticular lamina it is part of connective tissue consist of reticular fibres and collagen fibres and a part of underlying connective tissue.
 Epithelial cells are joined together by cellular junction between adjacent cells such as desmosomes or macula adherens  (adhering junction)

Epithelial tissue are  avascular (does not contain any blood vessels) Oxygen and nutrients diffuse to the epithelial cells from the blood capillaries located in the connective tissue beneath the basement membrane,conversely the carbon dioxide and metabolic waste products diffuse from the epithelial cells to the blood capillaries.
All materials which are leaving or entering the body must ultimately cross at least one layer of epithelial tissue.
The epithelium has good power of regeneration.
The epithelium membrane constantly renew and loss,the entire epidermis is completely replaced in every 2 weeks and stomach lining in two to three days.

The epithelium of the body are divided into two general groups
1 Glandular epithelium
 The glandular  epithelium are those which make the secretary portion of the gland of the body and also line their duct.
2 The covering epithelial
 They form continuous sheets of one or more layers of cell,that covers the different parts of the body externally and internally.
Epithelial tissue are of two types
simple epithelium
consist of  single layer simple epithelial tissue are classified on the basis of shape and the number of layers.
1 simple squamous epithelium
consists of a single layer of tightly packed flattened cells with a desk shape Central nucleus.
main example of simple squamous is endothelium which cover the internal surface of heart,blood vessels and lymph vessels.
The other main example is mesothelium which lines the pericardial.pleural and peritoneal cavities.
Simple squamous epithelium are also present in air sacs of lungs and kidney glomeruli.
 Function
 allows passage of Material by filtration and diffusion
2 simple cuboidal.
The cells are in cuboidal manner and similarly resting on basement membrane
Location
Small salivary and pancreatic duct.often form microvilli which increase surface area for absorption.
Also found in proximal convulated tubule.

Function:
Secretion and absorption.

3 simple columnar:

Consist of single layer of elongated cells.

Simple Columnar epithelium lines the lumen  of stomach and intestine(Digestive tract).

Function
Absorption and enzyme secretion.

4 Cilliated columnar epithelium.
Line the uterine fallopian tube and in the respiratory passage. contain numerous cilia that can move in coordinated fashion and aid the function of these organ.
Also found i ventricle of brain and Central Canal of spinal cord.

5 cilliated Cuboidal:
When simple cuboidal bears cilia called ciliated cuboidal
Location:
parts of nephron.

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