Daltonism: In the risk group of a man

History Daltonism

Delicate greens of May foliage and bloody-red sunset fire, deep seawater blue and hot yellow sandy sands... Many colors and shades carries the world. But whether his palette is the same for people living on earth? No, because congenital color vision in people is different.

The first found that some people are deprived of the opportunity, distinguish between certain colors, English chemist and physicist John Dalton. In 1794, he described him inherent in the very impact of view: the inability to distinguish red and green. By the name of the discoverer, this disadvantage and received the name of Daltonism. Special sensation discovery did not cause. It was perceived more like a certain curiosity, leading to small household inconveniences, like the impossibility of collecting a red strawberry in the green grass. True, over time, surprising detail turned out: congenital color blindness - for the rarest exceptions - is characterized only by men. In addition, «unmanimed» Occasionally applies blue (purple) color.

After a hundred years, a new interest arose to the problem of Daltonism - in connection with the rapid development of transport. Traffic lights appeared on the roads, and the ranlets behind the wheel became a source of danger. Soon measures taken: before getting driving permission, you need to pass test tests. The one who could distinguish between one-color background circles numbers or figures made up of circles of the same brightness, but another color, received the right to drove. If the tested color vision is not in order, then it cannot be done and, accordingly, cannot be a driver.

But not only transport problems attracted attention to the daltonism. He was interested in scientists: first physiologists, and then experts in heredity.

Why some people distinguish colors, and others - no

Still answered this question exhaustively fails. It is known that the cells located in the retina, similar in shape on the chemical flask (they, by the way, are called - Kolzkov), are divided into three types. Each type of cells is excited by one of three colors: red, green or blue. True, they all react to other colors. There are special painted substances in the cells - pigments that transmit light waves of only a certain length. Excitation of one «Sort» cells gives a feeling of the corresponding color, except for white, which is obtained when «Inclusion» All columns. All other colors and shades - complex variations of intermediate states. If there is no one of the pigments in the columns, then a person cannot see the corresponding color. In addition, because of such a fallout, the perception of some shades is distorted. This theory, however, explains not all congenital disturbances of color perception. Therefore, recently scientists suggest that the Daltonians have a somewhat different pigment that does not cope with their duties. This situation is possible: Normal pigments, but they fall into «not» Cells - for example, «green» Pigment turns out to be B «Red» Kolloches. Such confusion makes it difficult to transmit other, normal signals to the brain. But explain - does not mean cured. Unfortunately, the methods of treatment of congenital color blindness do not yet exist (although contact lenses appeared in the West, with the help of which the Daltonists manage to see the world in its pristine glea).

And now about why such a attack is collapsed mainly on men. Genetics were able to answer this question. It turned out that «responsibility» For the occurrence of daltonism in men lies on... Women. They are hidden carriers of a defective gene, causing disorders of color. Why in a male body this gene manifests itself, and in women - no? The fact is that a pair of chromosomes responsible for half a person exists in two versions. In women, its components are identical, and men - no. Women's genital chromosomes are taken to denote Latin letter «X». In women, two X chromosomes (XX), and in a man, except X-chromosome, there is still a small chromosome, which is denoted by the Latin letter «player». I.e «gentlemanly» Set is XY. The Dalton Gene Gene lies in the X-chromosome, and «power» It is small. If a person has a normal, unchanged gene, then he cannot manifest itself. It is clear that in women with two X chromosomes, the appearance of congenital color blindness is possible only when defective genes will be in both chromosomes. Similar situation extremely rare. But in the Y-chromosome there is no gene capable «Put» his unsuccessful partner, so the Dalton gene gene manifests itself in men quite often.

Surprisingly, many people with disturbed color perception will know about this one who accidentally. It turns out, they gradually «Learn» distinguish between the color according to the degree of their brightness that partly compensates for their disadvantage. And they make it so successful that «Expose» This Okol Path of Perception is capable only by a specialist.

The world happens black and white

Sometimes there is a complete color blindness: a person sees the whole world in black and white tones.

In addition to innate features, the color partition may be violated due to diseases of the organs of vision or central nervous system. At the same time, the perception of all three main colors is reduced. Timely treatment usually allows you to restore normal color.

With long-term exposure to the color on the eye, the color sensitivity of the retina can decrease to such a state that two different colors will be perceived as the same. This phenomenon of color fatigue.

The color is quite strong on the psyche and the physiological state of the person. The most favorable effect on sight is yellow-green and blue gamma colors.

Women, as a rule, more subtle than men distinguish with shades and are able to see more of their number.