Melanin is a general name of the whole group of the pigments which are contained in indumentum, skin, an iris of the eye of an eye and even internals of some animals. There are such pigments and in a human body.
The main function of melanin is to protect an organism from surplus of ultra-violet radiation. For this reason skin cells begin to produce strongly it when skin is exposed to the strengthened influence of sunshine or artificial radiation, similar to them. People call it suntan. During different eras the attitude towards suntan changed: once it was considered the accessory of commoners which is not appropriate to noble ladies, in the latest times it became fashionable, but physicians recommend to observe a measure in this case.
Manufacturing cells of melanin
Special cages – melanotsita "are responsible" for production of melanin. Such cage resembles a tree because of a large number of shoots superficially. On these shoots melanosoma – the granules containing melanin move. These granules may contain one of three types of melanin: eumelanin (black pigment), felomelanin (yellow) or fakomelanin (brown). All variety of flowers of human skin, a hair and an eye is defined by quantity, the size and arrangement melanosy.
The more melanosy and the larger they by the size, the will be more dark hair and vice versa. If melanin is not put into granules, and located in cages diffuzno, hair will be red. The iris of the eye of an eye has five layers. If melanin is available only in the deepest layers, they appear through color layers, and eyes look blue or blue. Presence of melanin at blankets does eyes brown or yellow at uniform distribution of melanin, and at uneven – gray or green.
Melanin synthesis
The predecessor of melanin in an organism – tyrosine. It is one of replaceable amino acids which the organism can not only receive with food, but also synthesize. With its participation also other substances, for example, hormone adrenaline are formed. Other substances necessary for melanin synthesis – oxygen and some derivatives of phenol. Both tyrosine, and derivatives of phenol enter chemical reaction with oxygen. The catalyst role in this reaction undertakes enzyme tyrosinase. As a result of a series of chemical reactions, tyrosine turns into DOFA-quinone, then – into DOFA-chrome, into dihydroxyindolcarbonic acid, and finally – into melanin, the substance consisting for 55% of carbon for 30% from oxygen, for 9% from hydrogen, for 4% from nitrogen, and 2% fall to the share of other substances.
Melanin synthesis violations
Melanotsita develop from melanoblast – the embryonic cages located in a nervous crest. From there they migrate in epidermis – the upper layer of the skin. If migration did not happen, the person is born an albino, it will have no melanin. The same occurs at a mutation of a gene responsible for synthesis of tyrosine or tyrosinase. Violation of synthesis of melanin leads not only to certain features of appearance. It is established that albinos have weaker immunity, badly transfer bright light, at them the risk is higher to develop skin cancer.