therapeutic cloning Cloning designed as therapy for a disease. In therapeutic cloning, the nucleus of a cell, typically a skin cell, is inserted into a fertilized egg whose nucleus has been removed. The nucleated egg begins to divide repeatedly to form a blastocyst. Scientists then extract stem cells from the blastocyst and use them to…
therapy The treatment of disease. Therapy is synonymous with treatment.
thermometer In medicine, a device used to measure the temperature of the human body. There are many types of medical thermometers, including oral thermometers (placed under the tongue), rectal thermometers (placed within the rectum), multipurpose thermometers (placed under the tongue, in the rectum, or under the armpit), eardrum thermometers (placed inside the ear), and basal…
thiamine Vitamin B1, which acts as a coenzyme in the metabolism of the body. In its active form, thiamine participates in a range of biochemical reactions, including certain reactions that are important to carbohydrate metabolism. Deficiency of thiamine leads to the disease beriberi. See also Appendix C, “Vitamins.”
thigh The thick, muscular portion of the leg that extends from the hip to the knee. The thigh has only one bone, the femur, which is the largest bone in the human body.
thighbone See femur.
third and fourth pharyngeal pouch syndrome See DiGeorge syndrome.
third ventricle One cavity in a system of four communicating cavities within the brain that are continuous with the central canal that contains the spinal cord. The third ventricle is a median (midline) cavity in the brain and is bounded by the thalamus and hypothalamus on either side. It communicates anteriorly (in front) with the…
thoracentesis Removal of fluid from the space between the lungs and the chest wall (the pleural cavity) for diagnostic or therapeutic purposes using a needle inserted between the ribs.
thoracic Pertaining to the chest. For example, the thoracic aorta is the part of the aorta that lies within the chest.
thoracic aorta The part of the aorta that lies within the chest. The thoracic aorta starts after the arch of the aorta and runs down to the diaphragm, the great muscle that separates the chest from the abdomen. The thoracic aorta gives off numerous branches that supply oxygenated blood to the chest cage and the…
thoracic duct A vascular structure that recirculates lymph from the lymphatic circulation into the bloodstream. The thoracic duct begins in the abdomen, tracks alongside the aorta and esophagus, and eventually joins with the left brachiocephalic vein.