Types of Tissues (:

Well first of all, tissues are a group of similar cells that do are responsible for a specific function.  The study of tissues is called histology.  There are four major types in the human body which are epithelial, connective, muscle, and nervous.  These tissues are responsible for the association, assembly, and interactions to form organs that have certain functions. I am going to talk about epithelial tissues and what they do.

Epithelial tissues: Responsible for covering all free body surfaces

• Covers the organs
• Forms the inner lining of the body cavities and lines our hollow organs.
• The basement membrane holds epithelial tissue to underlying connective tissue.
• Lack blood vessels
• Tightly packed

Epithelial tissues are classified by shape and the number of layers of cells. 

 Squamous: Thin, flattened cells

 Cuboidal: Cubelike cells

Columnar: Elongated cells

Simple:Single layer of cells

Stratified:2 or more layers

Simple Squamous-Single layers of thin, flattened cells. They fit tightly together and their nuclei are usually broad and thin.

-Common at sites of diffusion and filtration.

-Lines the alveoli of the lungs

-Forms the walls of capillaries, lines the blood and lymph vessels, and covers membranes that line body cavities

Simple Cuboidal-Single layer of cube-shaped cells which usually have a central location for the spherical nuclei.

-Lines the follicles of the thyroid gland, covers the ovaries, and lines the kidney tubules and ducts of glands

           *salivary glands

           *pancreas

           *liver

Simple Columnar-Single layer of elongated cells with nuclei that are at the same level near the basement membrane.  

-Cells can be ciliated or non ciliated. 

-They move constantly

-Some simple columnar cells are used for absorption.

Psuedostratified Columnar Epithelium-Appear stratified or layered, but really aren't.
-This layered effect occurs because the nuclei are at 2 or more levels in the aligned cell row.
-These cells vary in shape and reach the basement membrane.
-These types of cells have cilia

Stratified Squamous Epithelium-Many layers of cells, which make the tissue relatively thick.
-Cells nearest the free surface get flattened the most.
**Fun Fact-the epidermis is stratified squamous epithelium.

Stratified Cuboidal Epithelium-2-3 layers of cuboidal cells that form the lining of a lumen.
-Provides more protection for cells
-Lines the larger ducts of the mammary glands, sweat glands, salivary glands, and pancreas

Stratified Columnar Epithelium-Made of several layers of cells
-Elongated cells
-Found in part of the male urethra and ductus deferens.