Dictionary

sebum An oily secretion of the sebaceous glands that helps to preserve the flexibility of the hair and retain moisture in the skin. Sebum is also secreted by the Meibomian glands of the eyes. See also gland, Meibomian.

Seckel syndrome A rare inherited form of dwarfism and growth delay. Other symptoms and features associated with Seckel syndrome include an abnormally small head (microcephaly); varying degrees of mental retardation; and/or unusual characteristic facial features including “beak-like” protrusion of the nose. The syndrome is inherited in an autosomal recessive manner and can be due to…

second cranial nerve See optic nerve.

second stage of labor The part of labor that lasts from the full dilatation of the cervix until the baby is completely out of the birth canal. Also known as the stage of expulsion. See also labor.

secondhand smoke Smoke that comes from the burning end of a cigarette or that is exhaled by smokers. Inhalation of secondhand smoke is called involuntary or passive smoking. It can cause the same illnesses, including lung cancer, that actually smoking cigarettes causes. Also known as environmental tobacco smoke (ETS).

Scheuermann’s disease A skeletal disease that usually begins in adolescence in which the vertebrae grow unevenly, resulting in wedge-shaped vertebrae and a hunched back. Treatment with casting and a back brace is successful if undertaken early. Also known as juvenile kyphosis and curvature of the spine.

schistosomiasis See bilharzia.

schizoaffective disorder A mood disorder that is coupled with some symptoms that resemble those of schizophrenia, particularly loss of personality (flat affect) and social withdrawal.

schizoid Having symptoms similar to those of schizophrenia.

schizophrenia One of several brain diseases whose symptoms may include loss of personality (flat affect), agitation, catatonia, confusion, psychosis, unusual behavior, and social withdrawal. The illness usually begins in early adulthood. The cause of schizophrenia is not known, but there appear to be both genetic (inherited) and environmental components to the disease. Schizophrenia is not…

schizophrenia, childhood The onset of schizophrenia before adulthood. This condition is very rare in young children, but it occurs with more frequency in the teenage years. Autism was once known as childhood schizophrenia, but it is a completely different disorder. See also autism; childhood disintegrative disorder; developmental disorder; schizophrenia.

schizotypal personality disorder A personality type that is characterized by unusual patterns of speech and behavior and by social withdrawal. See also Asperger syndrome.