What are Tissues?
The word tissue is derived from a Latin word meaning to "weave." Cells that make up tissues are sometimes "woven" together with extracellular fibers.
Likewise, a tissue can sometimes be held together by a sticky substance that coats its cells.
There are four main categories of tissues: epithelial, connective, muscle and nervous. Let's take a look at epithelial tissue.
Likewise, a tissue can sometimes be held together by a sticky substance that coats its cells.
There are four main categories of tissues: epithelial, connective, muscle and nervous. Let's take a look at epithelial tissue.
Epithelial Tissue
Epithelial tissue covers the outside of the body and lines organs and cavities. The cells in this type of tissue are very closely packed together and joined with little space between them.
With a tightly packed structure we would expect epithelial tissue to perhaps serve some type of barrier and protective function and that is certainly the case.
Epithelial tissue helps to protect organisms from microorganisms, injury, and fluid loss.
In an epithelium, the free surface is usually exposed to fluid or the air while the bottom surface is attached to a basement membrane.
With a tightly packed structure we would expect epithelial tissue to perhaps serve some type of barrier and protective function and that is certainly the case.
Epithelial tissue helps to protect organisms from microorganisms, injury, and fluid loss.
In an epithelium, the free surface is usually exposed to fluid or the air while the bottom surface is attached to a basement membrane.
Classifying
Epithelia are commonly classified based on the shape of the cells on the free surface, as well as the number of cell layers. Sample types include:
Simple Epithelium: A simple epithelium has a single layer of cells.
Stratified Epithelium: A stratified epithelium has multiple layers of cells.
Likewise, the shape of the cells on the free surface can be:
Cuboidal
Analogous to the shape of dice.
Columnar
Analogous to the shape of bricks on an end.
Squamous
Analogous to the shape of flat tiles on a floor.
By combining the terms for shape and layers, we can derive epithelial types such as stratified squamous epithelium or simple columnar epithelium.
Simple Epithelium: A simple epithelium has a single layer of cells.
Stratified Epithelium: A stratified epithelium has multiple layers of cells.
Likewise, the shape of the cells on the free surface can be:
Cuboidal
Analogous to the shape of dice.
Columnar
Analogous to the shape of bricks on an end.
Squamous
Analogous to the shape of flat tiles on a floor.
By combining the terms for shape and layers, we can derive epithelial types such as stratified squamous epithelium or simple columnar epithelium.
Animal Tissue Types
To learn more about animal tissues, visit:
- Connective Tissue
- Muscle Tissue
- Nervous Tissue
- Nervous Tissue - Glial Cells
Share Your Opinions
What do you think? Have questions about animal tissue types or epithelial tissue? Come on over to the Biology Forum and share your thoughts, opinions, and feelings...........
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