Excessive exposure to UV radiation primarily affects which component of the skin?

Excessive exposure to UV radiation primarily affects melanin levels in the skin. Melanin is the pigment responsible for the color of the skin, and it plays a crucial role in protecting the skin from harmful UV rays. When the skin is exposed to UV radiation, it stimulates melanocytes, the cells that produce melanin, to increase melanin production. This is the body's natural response to protect deeper layers of the skin from UV damage. As a result, individuals often develop a tan, which is essentially an increase in melanin concentration.

Understanding this process highlights the importance of melanin in skin protection against UV radiation, while the other components mentioned, although affected by UV exposure in various ways, do not directly relate to the immediate response of the skin to UV rays in terms of pigmentation and protection.