tardive dyskinesia A neurological syndrome characterized by repetitive, involuntary, purposeless movements caused by the long-term use of certain drugs called neuroleptics used for psychiatric, gastrointestinal, and neurological disorders. Features may include grimacing; tongue protrusion; lip smacking, puckering, and pursing; and rapid eye blinking. Rapid movements of the arms, legs, and trunk may also occur. The…
tarsal cyst See cyst, Meibomian.
tarsal gland See gland, Meibomian.
tarsal tunnel syndrome Symptoms caused by compression of the nerve in the ankle and foot, usually from the trauma of repetitive work involving the ankle. Abbreviated TTS. Obesity, pregnancy, hypothyroidism, arthritis, and diabetes predispose a person to TTS. Symptoms include numbness and tingling of the foot and toes, a “pins and needles” feeling at night,…
tartar The hardened product of minerals from saliva and foods that accumulates in plaque around the teeth. Dental plaque and tartar cause periodontal disease, including inflammation of the bone surrounding the teeth. Tartar can become as hard as rock, becoming removable only by a dentist or dental hygienist with special tools.
taste A perception that results from stimulation of a gustatory nerve. Taste belongs to the chemical sensing system. Tasting begins when molecules stimulate special cells in the mouth or throat. These special cells transmit messages through nerves to the brain, where specific tastes are identified. Gustatory, or taste, cells react to food and beverages. The…
taste bud One of the tiny, barrel-shaped endings of the gustatory nerve located around the base of the papillae (small bumps) on the tongue.
tattoo The permanent insertion of ink below the skin, using a sharp instrument. Humans have done tattooing for cosmetic and ritual purposes since at least the Neolithic era. Today the practice is made relatively safe by the use of nonreactive pigments; sterile, disposable needles; and sterile work conditions. Without these refinements, inks may cause inflammation,…
tattoo removal Removal of a tattoo, as with the use of lasers to destroy the ink itself. Multiple treatments may be necessary, depending on the size of the piece and the inks used. Some tattoos cannot be completely removed with lasers, and lasers may scar some types of skin.
Tay-Sachs disease A genetic metabolic disorder caused by deficiency of the enzyme hexosaminidase A (hex-A) that results in failure to process GM2 ganglioside, a lipid (fat) that then accumulates in the brain and other tissues. Abbreviated TSD. The classic form of TSD begins in infancy. The child usually develops normally for the first few months,…
TB Tuberculosis.
Td Adult diphtheria and tetanus toxoids. See Td vaccine.