melanín

Melanin is a natural pigment found in most organisms, including humans. In humans, it is primarily responsible for the color of skin, hair, and eyes. Melanin is produced by specialized cells called melanocytes. The type and amount of melanin produced determine the variations in these physical characteristics.

There are two main types of melanin: eumelanin and pheomelanin. Eumelanin is responsible for brown and black coloration, while pheomelanin contributes to red and yellow hues. The ratio of these two pigments, along with the density of melanosomes (organelles containing melanin), dictates the precise color.

The primary function of melanin in the skin is photoprotection. It absorbs ultraviolet (UV) radiation from the sun, which can damage DNA and lead to skin cancer. Individuals with more eumelanin generally have darker skin and are more resistant to sun damage than those with less melanin. This is why people with lighter skin are more prone to sunburn and have a higher risk of developing melanoma.

Melanin also plays a role in other biological processes. For example, it is found in the iris of the eye, where it helps to regulate the amount of light entering the pupil and protects the retina from UV damage. In hair, melanin provides its color, and its gradual depletion over time leads to graying and eventually white hair. The production of melanin can be influenced by genetics, exposure to sunlight (tanning), and certain medical conditions.