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Albinism In Humans
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 rare cases such as Chédiak–Higashi syndrome, albinism may be associated with deficiencies in the transportation of melanin granules. This also affects essential granules present in immune cells leading to increased susceptibility to infection. Albinism results from inheritance of recessive gene alleles and is known to affect all vertebrates, including humans. It is due to absence or defect of tyrosinase, a copper-containing enzyme involved in the production of melanin. Unlike humans, other animals have multiple pigments and for these, albinism is considered to be a hereditary condition characterised by the absence of melanin in particular, in the eyes, skin, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dermatology
Dermatology is the branch of medicine dealing with the skin.''Random House Webster's Unabridged Dictionary.'' Random House, Inc. 2001. Page 537. . It is a speciality with both medical and surgical aspects. A dermatologist is a specialist medical doctor who manages diseases related to skin, hair, nails, and some cosmetic problems. Etymology Attested in English in 1819, the word "dermatology" derives from the Greek δέρματος (''dermatos''), genitive of δέρμα (''derma''), "skin" (itself from δέρω ''dero'', "to flay") and -λογία '' -logia''. Neo-Latin ''dermatologia'' was coined in 1630, an anatomical term with various French and German uses attested from the 1730s. History In 1708, the first great school of dermatology became a reality at the famous Hôpital Saint-Louis in Paris, and the first textbooks (Willan's, 1798–1808) and atlases ( Alibert's, 1806–1816) appeared in print around the same time.Freedberg, et al. (2003). ''Fitzpatrick's Dermatology in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Albinistic Girl Papua New Guinea
Albinism is the congenital absence of melanin in an animal or plant resulting in white hair, feathers, scales and skin and pink or blue eyes. Individuals with the condition are referred to as albino. Varied use and interpretation of the terms mean that written reports of albinistic animals can be difficult to verify. Albinism can reduce the survivability of an animal; for example, it has been suggested that albino alligators have an average survival span of only 24 hours due to the lack of protection from UV radiation and their lack of camouflage to avoid predators. It is a common misconception that all albino animals have characteristic pink or red eyes (resulting from the lack of pigment in the iris allowing the blood vessels of the retina to be visible), however this is not the case for some forms of albinism. Familiar albino animals include in-bred strains of laboratory animals (rats, mice and rabbits), but populations of naturally occurring albino animals exist in the wil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photophobia
Photophobia is a medical symptom of abnormal intolerance to visual perception of light. As a medical symptom photophobia is not a morbid fear or phobia, but an experience of discomfort or pain to the eyes due to light exposure or by presence of actual physical sensitivity of the eyes, though the term is sometimes additionally applied to abnormal or irrational fear of light such as heliophobia. The term ''photophobia'' comes from the Greek language, Greek φῶς (''phōs''), meaning "light", and φόβος (''phóbos''), meaning "fear". Causes Patients may develop photophobia as a result of several different medical conditions, related to the human eye, eye, the nervous system, genetic, or other causes. Photophobia may manifest itself in an increased response to light starting at any step in the visual system, such as: *Too much light entering the eye. Too much light can enter the eye if it is damaged, such as with corneal abrasion and retinal damage, or if its pupil(s) is unabl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Decussation
Decussation is used in biological contexts to describe a crossing (due to the shape of the Roman numeral for ten, an uppercase 'X' (), ). In Latin anatomical terms, the form is used, e.g. . Similarly, the anatomical term chiasma is named after the Greek uppercase 'Χ' (chi). Whereas a decussation refers to a crossing within the central nervous system, various kinds of crossings in the peripheral nervous system are called chiasma. Examples include: * In the brain, where nerve fibers obliquely cross from one lateral side of the brain to the other, that is to say they cross at a level other than their origin. See for examples Decussation of pyramids and sensory decussation. In neuroanatomy, the term ''chiasma'' is reserved for crossing of- or within nerves such as in the optic chiasm. * In botanical leaf taxology, the word ''decussate'' describes an opposite pattern of leaves which has successive pairs at right angles to each other (i.e. rotated 90 degrees along the stem when ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mali Salif Keita2 400
Mali (; ), officially the Republic of Mali,, , ff, 𞤈𞤫𞤲𞥆𞤣𞤢𞥄𞤲𞤣𞤭 𞤃𞤢𞥄𞤤𞤭, Renndaandi Maali, italics=no, ar, جمهورية مالي, Jumhūriyyāt Mālī is a landlocked country in West Africa. Mali is the eighth-largest country in Africa, with an area of over . The population of Mali is million. 67% of its population was estimated to be under the age of 25 in 2017. Its capital and largest city is Bamako. The sovereign state of Mali consists of eight regions and its borders on the north reach deep into the middle of the Sahara Desert. The country's southern part is in the Sudanian savanna, where the majority of inhabitants live, and both the Niger and Senegal rivers pass through. The country's economy centres on agriculture and mining. One of Mali's most prominent natural resources is gold, and the country is the third largest producer of gold on the African continent. It also exports salt. Present-day Mali was once part of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photosensitivity
Photosensitivity is the amount to which an object reacts upon receiving photons, especially visible light. In medicine, the term is principally used for abnormal reactions of the skin, and two types are distinguished, photoallergy and phototoxicity. The photosensitive ganglion cells in the mammalian eye are a separate class of light-detecting cells from the photoreceptor cells that function in vision. Skin reactions Human medicine Sensitivity of the skin to a light source can take various forms. People with particular skin types are more sensitive to sunburn. Particular medications make the skin more sensitive to sunlight; these include most of the tetracycline antibiotics, heart drugs amiodarone, and sulfonamides. Some dietary supplements, such as St. John's Wort, include photosensitivity as a possible side effect. Particular conditions lead to increased light sensitivity. Patients with systemic lupus erythematosus experience skin symptoms after sunlight exposure; some types ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retina
The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then processes that image within the retina and sends nerve impulses along the optic nerve to the visual cortex to create visual perception. The retina serves a function which is in many ways analogous to that of the film or image sensor in a camera. The neural retina consists of several layers of neurons interconnected by synapses and is supported by an outer layer of pigmented epithelial cells. The primary light-sensing cells in the retina are the photoreceptor cells, which are of two types: rods and cones. Rods function mainly in dim light and provide monochromatic vision. Cones function in well-lit conditions and are responsible for the perception of colour through the use of a range of opsins, as well as high-acuity vision used for task ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iris (anatomy)
In humans and most mammals and birds, the iris (plural: ''irides'' or ''irises'') is a thin, annular structure in the eye, responsible for controlling the diameter and size of the pupil, and thus the amount of light reaching the retina. Eye color is defined by the iris. In optical terms, the pupil is the eye's aperture, while the iris is the diaphragm. Structure The iris consists of two layers: the front pigmented fibrovascular layer known as a stroma and, beneath the stroma, pigmented epithelial cells. The stroma is connected to a sphincter muscle (sphincter pupillae), which contracts the pupil in a circular motion, and a set of dilator muscles ( dilator pupillae), which pull the iris radially to enlarge the pupil, pulling it in folds. The sphincter pupillae is the opposing muscle of the dilator pupillae. The pupil's diameter, and thus the inner border of the iris, changes size when constricting or dilating. The outer border of the iris does not change size. The constricti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sunburn
Sunburn is a form of radiation burn that affects living tissue, such as skin, that results from an overexposure to ultraviolet (UV) radiation, usually from the Sun. Common symptoms in humans and animals include: red or reddish skin that is hot to the touch or painful, general fatigue, and mild dizziness. Other symptoms include blistering, peeling skin, swelling, itching, and nausea. Excessive UV radiation is the leading cause of (primarily) non-malignant skin tumors,World Health Organization, International Agency for Research on Cance"Do sunscreens prevent skin cancer" Press release No. 132, 5 June 2000World Health Organization, International Agency for Research on Cance"Solar and ultraviolet radiation"IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 55, November 1997 and in extreme cases can be life-threatening. Sunburn is an inflammatory response in the tissue triggered by direct DNA damage by UV radiation. When the cells' DNA is overly damag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiation
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes: * ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma radiation (γ) * ''particle radiation'', such as alpha radiation (α), beta radiation (β), proton radiation and neutron radiation (particles of non-zero rest energy) * '' acoustic radiation'', such as ultrasound, sound, and seismic waves (dependent on a physical transmission medium) * ''gravitational wave, gravitational radiation'', that takes the form of gravitational waves, or ripples in the curvature of spacetime Radiation is often categorized as either ''ionizing radiation, ionizing'' or ''non-ionizing radiation, non-ionizing'' depending on the energy of the radiated particles. Ionizing radiation carries more than 10 electron volt, eV, which is enough to ionize atoms and molecules and break ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultraviolet
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight, and constitutes about 10% of the total electromagnetic radiation output from the Sun. It is also produced by electric arcs and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights. Although long-wavelength ultraviolet is not considered an ionizing radiation because its photons lack the energy to ionization, ionize atoms, it can cause chemical reactions and causes many substances to glow or fluorescence, fluoresce. Consequently, the chemical and biological effects of UV are greater than simple heating effects, and many practical applications of UV radiation derive from its interactions with organic molecules. Short-wave ultraviolet light damages DNA and sterilizes surf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Organization For Albinism And Hypopigmentation
The National Organization for Albinism and Hypopigmentation (NOAH) is a non-profit organization that assists people who have albinism. NOAH was created in 1982 and is based in East Hampstead, New Hampshire. NOAH is operated by volunteers. It is funded primarily by member dues and contributions. NOAH also receives received grants for specific projects, such as its handbook for new parents. The NOAH board of directors has committees on advocacy, conferences, financial development, albinism awareness, and editorial. NOAH sponsors workshops and conferences on albinism. It also publishes a quarterly magazine, ''Albinism InSight'', information bulletins, a network of local chapters and contact people, an informational Web site and bulletin boards. The objective is to disseminate correct information about albinism through the media, libraries, medical professionals, and support groups for people with albinism in the United States and other countries the Albinism World Alliance. Adv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
