What is the Origin of UV Radiation?

The term originates from physics and astronomy, describing the portion of the electromagnetic spectrum beyond the visible violet light. Its clinical and physiological relevance stems from the discovery of its role in vitamin D metabolism and its profound impact on skin health and immune function. The biological effects of this radiation have been studied extensively since the early 20th century.

What is the Mechanism of UV Radiation?

The mechanism of its beneficial action involves UVB photons penetrating the epidermis, where they strike 7-dehydrocholesterol, converting it into pre-vitamin D3. This precursor is then thermally isomerized into vitamin D3, which is further hydroxylated in the liver and kidneys to form the active hormone, calcitriol. Beyond vitamin D, UV exposure also influences nitric oxide release, impacting cardiovascular and metabolic function.

UV Radiation ∞ Area

UV Radiation

Meaning

Electromagnetic radiation emitted by the sun, spanning wavelengths from 10 nm to 400 nm, which is subdivided into UVA, UVB, and UVC bands based on energy and penetration depth. While excessive exposure is a known risk factor for dermatological damage, controlled exposure to UVB is a critical physiological stimulus for the cutaneous synthesis of pre-vitamin D. UV radiation thus plays a dual role in health, balancing photochemical damage with essential endocrine signaling.