Basic Biology


Where is epithelial tissue found?

Cell Type Average Lifespan
Blood cells: Red blood cells 120 days
Blood cells: Lymphocytes Over 1 year
Blood cells: Other white cells 10 hours
Blood cells: Platelets 10 days
Bone cells 25–30 years
Brain cells* Lifetime
Colon cells 3–4 days
Liver cells 500 days
Skin cells 19–34 days
Spermatozoa 2–3 days
Stomach cells 2 days
* Brain cells are the only cells that do not divide further during a person’s lifetime. They either last the entire lifetime, or if they die during a person’s lifetime they are not replaced.

Epithelial tissue, also called epithelium (from the Greek epi, meaning “on,” and thele, meaning “nipple”), covers every surface, both external and internal, of the body. The outer layer of the skin, the epidermis, is one example of epithelial tissue. Other examples of epithelial tissue are the lining of the lungs, kidney tubules, and the inner surfaces of the digestive system, including the esophagus, stomach, and intestines. Epithelial tissue also includes the lining of parts of the respiratory system.


This is a web preview of the "The Handy Anatomy Answer Book" app. Many features only work on your mobile device. If you like what you see, we hope you will consider buying. Get the App