Medical Terminology
Glossary
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labia majora - two longitudinal folds of skin extending downward and backward from the mons pubis of the female
labia minora - two small folds of mucous membrane lying medial to the labia majora of the female
labial frenulum - the medial fold of mucous membrane between the inner surface of the lip and the gums
labium - a lip; a liplike structure; plural, labia
labyrinth - an intricate communicating passageway, especially in the internal ear
labyrinthine disease - malfunction of the internal ear characterized by deafness, tinnitus, vertigo, nausea, and vomiting
laceration - wound or irregular area of the skin
lacrimal - pertaining to tears
lactation - the secretion and ejection of milk by the mammary glands
lacteal - one of many lymphatic vessels in the intestinal villi; they absorb fat molecules from digested food
lacuna - a small, hollow space, such as those in which the osteoblasts lie within bones; plural, lacunae
lambdoidal suture - the line of union between the parietal bones and the occipital bone in the skull; sometimes contains sutural (Wormian) bones
lamellae - concentric rings found in compact bone
lamina - a thin, flattened layer or membrane, as the flattened part on either side of the arch of a vertebra; plural, laminae
lamina propria - the connective tissue layer of a mucous membrane
lanugo - fine downy hairs that cover the fetus
laparoscopy - insertion of a laparoscope through an abdominal incision to: view abdominal and pelvic viscera, remove fluids or tissues for biopsy, drain ovarian cysts, cut adhesions, stop bleeding, and perform tubal ligation
laryngitis - an inflammation of the mucous membrane lining the larynx
laryngopharynx - the inferior portion of the pharynx, extending downward from the level of the hyoid bone to divide posteriorly into the esophagus & anteriorly into the larynx
laryngoscope - instrument for examining the larynx
laryngotracheal bud - outgrowth of foregut endoderm from which the respiratory system develops
larynx - the voice box, a short passageway that connects the pharynx with the trachea
lateral - farther from the midline of the body or a structure
lesion - any localized, abnormal change in tissue formation
lesser omentum - the fold of peritoneum that extends from the liver to the lesser curvature of the stomach & the commencement of the duodenum
lethargy - a condition of drowsiness or indifference
leukemia - a malignant disease of the blood-forming tissues with acute overproduction and accumulation of immature leucocytes, many of which fail to reach maturity, or with chronic accumulation of mature lymphocytes because they do not die at the end of a normal lifespan
leukocyte - a white blood cell
leukocytosis - an increase in the number of white blood cells, characteristic of many infections and other disorders
leukopenia - a decrease in the number of white blood cells below 5,000 per cubic millimeter
leukoplakia - a disorder in which there are white patches in the mucous membranes of the tongue, gums, and cheeks
libido - the sexual drive, conscious or unconscious
ligament - dense, regularly-arranged connective tissue attaching bone to bone
ligand - a chemical in interstitial fluid, usually in a concentration lower than that in cells
lingual frenulum - a fold of mucous membrane that connects the tongue to the floor of the mouth
lipase - a fat-splitting enzyme
lipogenesis - synthesis of lipids from glucose or amino acids by the cells in the liver
lipoma - a fatty tissue tumor, usually benign
lipoprotein - a protein containing lipid; some made in the liver bind cholesterol & triglycerides to raise their solubility in blood; high levels of LDL's (low-density) are risk factors for atherosclerosis & high levels of HDL's (high-density) are protective against it
lithotripsy - a noninvasive procedure in which shock waves generated by an instrument called a lithotriptor are used to pulverize kidney stones or gallstones
lobe - any curved or rounded projection of a structure
locus coeruleus - a cluster of neurons in the brain stem where norepinephrine (NE) is concentrated
lordosis - exaggeration of the lumbar curve of the vertebral column
lumbar - region of the back and side between the ribs and pelvis; loin
lumen - the space within a tubular structure such as a blood vessel or the intestine
lunula - the moon-shaped, white area at the base of a nail
luteinizing hormone (LH) - adenohypophysal hormone which, in females, stimulates ovulation and progesterone secretion by the corpus luteum and readies the mammary glands for milk production; in males, it stimulates testosterone secretion by the testes
lymph - fluid confined in lymphatic vessels & flowing through the lymphatic system to be returned to the blood
lymphangiography - a procedure in which lymphatic vessels and lymph organs are filled with a radiopaque substance to be X-rayed
lymphatic vessel - a large vessel that collects lymph from lymph capillaries & converges with other lymphatic vessels to form the thoracic and right lymphatic ducts
lymphocyte - a type of white blood cell, found in lymph nodes, associated with the immune system
lymphokines - powerful proteins secreted by T lymphocytes; they stimulate the various activities of B and T cells in immune responses
lysosome - organelle in the cytoplasm of a cell, enclosed by a single membrane and containing powerful digestive enzymes
lysozyme - bactericidal enzyme found in tears, saliva, and perspiration