User:Anatomy244/sandbox/Albinism
From Wikipedia, the free encyclopedia
Albinism Albinism refers to a range of disorders that are the result of reduction or absence of the pigment melanin.
Melanin Melanin is the pigment that is produced from a melanocyte in the stratum basale layer of the epidermis. The epidermis is an integral part of the integumentary system. Melanocytes are not only located in the epidermis of the human body. These cells are also scattered in the ear, eye, and brain tissues. An individual with albinism contains the normal number of melanocytes in the stratum basale layer of the epidermis, but these melanocytes lack the required enzyme to produce melanin.
Role of Melanin
Melanin and the Skin Melanin shields the nuclear DNA of the keratinocyte when exposed to UV radiation and works to protect the skin against harmful UV sun exposure. It also plays a role in protecting the individual against skin cancer. Melanin determines skin pigment of the individual. There is an inverse relationship in regards to melanin and risk of skin cancer. The more melanin produced (darker skin), the lesser the risk for skin cancer, and vice versa.
Melanin and the Eye Melanin provides the pigment of the iris and plays a role in vision. An individual with albinism lacks pigment in the iris of the eye, a region of the eye that is responsible for eye color.The pigment in the iris, melanin, is responsible for absorbing light. Melanin in the eye is also responsible for tolerating bright light. An individual with albinism will be very sensitive to bright light, a condition known as photosensitivity, due to the lack of melanin in the iris. An individual with albinism may also have other vision problems that are not necessarily associated with melanin production. This can include an underdeveloped fovea, the part of the eye that is responsible for visual acuity. Visual acuity refers to sharpness, or clarity of vision.
Stimulation of Melanin Production Exposure to UV light will stimulate the production of melanin, as melanin is used to protect a keratinocyte’s (in the stratum basale) nuclear DNA from UV exposure. There are also many specific genes such as MC1R and others that play a role in what type of melanin the body produces.