787 pages on this wiki. Mark Andrew Spitz (born February 10, 1950) is a retired American swimmer. He won seven gold medals at the 1972 Summer Olympics, an achievement only surpassed by Michael Phelps who won eight golds at the 2008 Olympics.Spitz set new world records in all seven events in which he competed, a record that still stands.87 pages on this wiki. Mark Andrew Spitz (born February 10, 1950) is a retired American swimmer. He won seven gold medals at the 1972 Summer Olympics, an achievement only surpassed by Michael Phelps who won eight golds at the 2008 Olympics.
The colour of the skin is determined by the concentrations of three main pigments: melanin, carotene and haemoglobin. These are found in the dermis and combine to produce the pigmentation of all surface tissues including the skin, mucous membranes, and even the eyes.
Also called pigment, melanin is a substance that gives the skin and hair its natural color. It also gives color to the iris of the eye, feathers, and scales. In humans, those with darker skin have higher amounts of melanin. By contrast, those with less pigment have lighter or more fair skin coloring. Melanin, sometimes referred to as a chemical, is formed as part of the process of metabolizing an amino acid called tyrosine. In the skin, melanin is formed by cells called melanocytes. Certain medical conditions, such as albinism, are associated with the lack of melanin.