Category: N

A repeated action used to alleviate stress, such as a cough, biting the nails, or pulling the hair. An informal expression used to describe a small, repetitive action or behavior. A nervous habit can involve involuntary movements like twitches and facial tics, seen in conditions like Gilles de la Tourette’s syndrome and certain types of…

A chemical warfare gas that is inhaled, ingested, or absorbed into the body through the skin. Nerve gas has paralyzing and other harmful effects, especially on the nervous and respiratory  systems. Effects of poisoning depend on the type of gas, but can include immediate death or long-term disability. Any gas that disrupts the normal functioning…

An antiviral drug. Nelfinavir mesylate (Viracept) is used along with other medicines to treat infection caused by HIV (human immunodeficiency virus). It works by preventing HIV from reproducing itself, thereby slowing the destruction of the human immune system and delaying the symptoms associated with aids (acquired immunodeficiency syndrome).  

A severe, life-threatening infection caused by bacteria that attack the soft tissue beneath the top layers of skin, including the fibrous tissue that covers the muscles. Necrotizing fasciitis group A is usually caused by group A Streptococcus and other bacteria that enter the body via an infection or minor cut or lesion on the surface…

Stiffness of the neck caused by spasm of the muscles in the neck and spine. Neck rigidity is an important symptom of meningitis (inflammation of the membranes that surround the brain and spinal cord). Neck stiffness can also be caused by injuries such as whiplash. Pronounced inflexibility of the neck results from muscle spasms affecting…

Thin bone projections that subdivide each nasal cavity into a series of groovelike passageways and curve from the outer part of the nose in toward the septum (cartilage wall between the nostrils). The turbinates are covered by thick mucous membranes. Under the membrane, sensitive, spongy, erectile tissue causes the tissues in the area to fill…

An antinarcotic drug. Naltrexone hydrochloride (Trexan, Re Via) is used to help a person addicted to a narcotic or alcohol stay substance-free. Naltrexone works by blocking the effects of narcotics, particularly the enjoyable “high” associated with drug and alcohol use.  

A hormone similar to one released from the hypothalamus. Nafarelin acetate (Synarel) is used to treat endometriosis, A disease in which the tissue that forms the uterine lining in women grows outside the uterus, and premature puberty in both boys and girls. Nafarelin acetate works by decreasing the amount of estrogen and testosterone in the blood.…

A conceptual approach to understanding psychological development and treating mental illness based on the clinical work and writings of Sigmund Freud. Freud was the founder of psychoanalysis, which is a widely used and highly influential technique for revealing the deep self and resolving psychological issues. Freudian theory is based on a number of Freud’s central…

A species of atom characterized by the constitution of its nucleus, in particular by the number of protons and neutrons. Thus, Co-59 and Co-60 are both isotopes of cobalt and are each nuclides. Co-60 is a radionuclide since it undergoes radioactive decay. An artificially produced isotope that emits radioactive waves and may be used in…