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.
The colour is due to pigment accumulating in the skin cells (keratinocytes). Skin pigment (melanin) is made by cells called melanocytes. They don't produce much melanin during the winter months, but produce more when exposed to the sun. The melanin is diffused into the surrounding skin cells, called keratinocytes.