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Heterochromia iridum. Heterochromia is a variation in coloration most often used to describe color differences of the iris, but can also be applied to color variation of hair [1] or skin. Heterochromia is determined by the production, delivery, and concentration of melanin (a pigment). It may be inherited, or caused by genetic mosaicism ...
A variety of human hair colors; from top left, clockwise: black, brown, blonde, white, red. Human hair color is the pigmentation of human hair follicles and shafts due to two types of melanin: eumelanin and pheomelanin. Generally, the more melanin present, the darker the hair. Its tone depends on the ratio of black or brown eumelanin to yellow ...
In humans, eye color is a highly sexually dimorphic trait. [17] Several studies have shown that men are more likely to have blue eyes than women, while women are more likely to have darker eye colors (green and brown eyes) than men. [17] [18] Sex is therefore a major factor in the expression of eye color genotypes. [17]
Auburn hair. Auburn hair is a human hair color, a variety of red hair, most commonly described as reddish - brown in color. Auburn hair ranges in shades from medium to dark. It can be found with a wide array of skin tones and eye colors. The chemical pigments that cause the coloration of auburn hair are frequently pheomelanin with high levels ...
Specialty. Dermatology. Albinism is a congenital condition characterized in humans by the partial or complete absence of pigment in the skin, hair and eyes. Albinism is associated with a number of vision defects, such as photophobia, nystagmus, and amblyopia. Lack of skin pigmentation makes for more susceptibility to sunburn and skin cancers.
In humans, melanin is the primary determinant of skin color. It is also found in hair, the pigmented tissue underlying the iris of the eye, and the stria vascularis of the inner ear. In the brain, tissues with melanin include the medulla and pigment-bearing neurons within areas of the brainstem, such as the locus coeruleus.
The iris (pl.: irides or irises) is a thin, annular structure in the eye in most mammals and birds, responsible for controlling the diameter and size of the pupil, and thus the amount of light reaching the retina. In optical terms, the pupil is the eye's aperture, while the iris is the diaphragm.
This is an accepted version of this page This is the latest accepted revision, reviewed on 16 September 2024. "Skin pigmentation" redirects here. For animal skin pigmentation, see Biological pigment. Extended Coloured family from South Africa showing some spectrum of human skin coloration Human skin color ranges from the darkest brown to the lightest hues. Differences in skin color among ...