Melanin has many biological functions, including colouring the skin and hairs or feathers, strengthening plant cell walls and insect cuticle, absorbing light (and so providing photoreceptor shieldlng, thermoregulation, photoprotectlon), and it is an important free radical sink.
Medical Definition of autistic disorder. : autism Autistic disorder is classic autism, one of the more severe disorders on the spectrum. Persons with autistic disorder have substantial impairment in social skills, verbal communication, and cognitive and behavioral flexibility.âIsabelle Rapin , The New England Journal of Medicine, 1 Aug. 2002.
a mood disorder marked by a hyperactive, widely optimistic state bipolar disorder a mood disorder in which the person alternates between the hopelessness and lethargy of depression and the overexcited state of mania. schizophrenia a group of severe disorders characterized by disorganized and delusional thinking, disturbed perceptions, and inappropriate emotions and actions