Ultraviolet radiation. Invisible rays that are part of the energy that comes from the sun, can burn the skin, and cause skin cancer. UV radiation is made up of three types of rays — ultraviolet A (UVA), ultraviolet B (UVB), and ultraviolet C (UVC).
UVC is the most dangerous type of ultraviolet light but cannot penetrate earth’s protective ozone layer. Therefore, it poses no threat to human, animal or plant life on earth. UVA and UVB, on the other hand, do penetrate the ozone layer in attenuated form and reach the surface of the planet. UVA is weaker than UVB but passes further into the skin than UVB. It is now generally accepted that both UVA and UVB cause skin cancer, including melanoma. For this reason, sunscreens are recommended that block both kinds of radiation — UVA and UVB.
In addition to natural light from the sun, artificial light from tanning lamps contains UVA and UVB. Electric arc lamps can also generate ultraviolet light to heat furnaces for melting and to enable motion-picture projectors to show movies.
Though ultraviolet light can damage health, it can also maintain or improve health. When ultraviolet light strikes human skin, it triggers the production of vitamin D, which promotes the growth of bones and teeth.
An inner layer of the eye that includes the iris, the blood vessels that serve the eye (choroid), and the connective tissue between the iris and the choroid (the ciliary body).
Inflammation of the uvea. Uveitis is a serious form of eye inflammation and requires aggressive treatment with medications to reduce the inflammation that can permanently impair vision. Uveitis can occur by itself or as a feature of an underlying disease, such as Behcet’s disease, sarcoidosis, and others.
The anatomic structure that dangles downward at the back of the mouth and is attached to the rear of the soft palate.
Inflammation of the uvula. Uvulitis has many causes, including infection with a virus, fungus, or bacteria or the result of a side effect of a medication.
A type of operation designed to tighten up flabby tissues and enlarge the upper air passages. The operation involves reshaping the uvula (uvulo-), soft palate (-palato-) and throat (-pharyngo-). The uvula is a small piece of soft tissue that can be seen dangling down from the soft palate over the back of the tongue. The […]