Definitions and descriptions
There are currently 52 terms in this directory beginning with the letter L.
Labia majora (LAY-bee-uh muh-JOR-ah)
The outer folds of skin of the vulva; enclose the labia minora and the vestibule.
The process by which a fetus is expelled from the uterus through the vagina to the exterior of the body.
1. A maze; an interconnected series of passageways. 2. In the inner ear, the bony labyrinth is a series of tunnels in the temporal bone lined with membrane called the membranous labyrinth.
Lacrimal glands (LAK-ri-muhl)
The glands that secrete tears, located at the upper, outer corner of each eyeball.
A digestive enzyme that breaks down lactose to glucose and galactose; secreted by the small intestine.
The lymph capillaries in the villi of the small intestine, which absorb the fat-soluble end products of digestion.
Lactic acid (LAK-tik ASS-id)
The chemical end product of anaerobic cell respiration; contributes to fatigue in muscle cells.
Lactose intolerance (LAK-tohs in-TAHL-er-ense)
The inability to digest lactose due to a deficiency of the enzyme lactase; may be congenital or acquired.
Langerhans cell (LAHNG-er-hanz SELL)
A mobile, phagocytic cell of the epidermis (Syn.—dendritic cell).
Is an infection caused by Corynebacterium diphtheria; it is directly transmitted from person to person by droplets. Children between 1-5 years of age are most susceptible although non-immune adults are also at risk.
The lower portion of the pharynx that opens into the larynx and the esophagus; a passageway for both air and food.
The organ that is an airway between the pharynx and the trachea; contains the vocal cords for speech (Syn.—voice box).
The oval structure of the eye posterior to the pupil, made of transparent protein; the only adjustable portion of the refraction pathway for the focusing of light rays.
Leprosy is a chronic granulomatous disease caused by Mycobacterium leprae. It mainly affects the skin, the peripheral nerves and the mucous membranes. Leprosy is the commonest cause of peripheral neuritis in the world.
Malignancy of blood-forming tissues, in which large numbers of immature and nonfunctional white blood cells are produced.
White blood cell; the five kinds are neutrophils, eosinophils, basophils, lymphocytes, and monocytes.
An elevated white blood cell count, often an indication of infection.
An abnormally low white blood cell count; may be the result of aplastic anemia, or a side effect of some medications.
Chemicals produced by basophils and mast cells from the phospholipids of their cell membranes; they increase capillary permeability and attract WBCs during inflammation.
A digestive enzyme that breaks down emulsified fats to fatty acids and glycerol; secreted by the pancreas.
An organic chemical insoluble in water; includes true fats, phospholipids, and steroids.
A large molecule that is a combination of proteins, triglycerides, and cholesterol; formed by the liver to circulate lipids in the blood.
Crushing of gallstones or renal calculi by an instrument that uses ultrasonic waves applied to the exterior of the body.
The organ in the upper right and center of the abdominal cavity; secretes bile for the emulsificationof fats in digestion; has many other functions related tothe metabolism of nutrients and the composition of blood.
Liver lobule (LIV-er LAH-byool)
The structural unit ofthe liver; a columnar hexagon of liver cells and sinusoids surrounding a central vein; includes the smallest bileducts.
Longitudinal section (LAWNJ-i-TOO-din-uhl SEKshun)
A plane or cut along the long axis of an organ or the body.
Loop of Henle (LOOP of HEN-lee)
The part of a renal tubule that extends from the proximal convoluted tubule to the distal convoluted tubule.
Low Back Pain
Low back pain is a common presenting complaint especially among the adult population. Severity may range from mild, transient symptom to chronic and disabling pain. Causes of low back pain are numerous and clues to the underlying cause can usually be found from a good clinical history and physical examination. In some patients however, no cause will be found, and these people are described as having nonspecific back pain.
Low vision is irreversible visual loss that cannot be corrected with surgeries or spectacles resulting in reduced ability to perform many daily activities. They have visual impairment even with treatment and or standard refractive correction.
Lower Abdominal Pain Syndrome or Pelvic Inflammatory Disease (PID)
PID is defined as the inflammation of the uterus, Fallopian tubes, ovaries and pelvic peritoneum. It is also known as lower abdominal pain syndrome. It commonly occurs as a result of infection ascending from the cervix. It can also occur as a result of trans-cervical procedure.
Lower esophageal sphincter (e-SOF-uh-JEE-uhl SFINK-ter)
The circular smooth muscle at the lower end of the esophagus; prevents backup of stomach contents (Syn.—cardiac sphincter).
Lower respiratory tract (LOH-er RES-pi-rah-TOR-ee TRAKT)
The respiratory organs located within the chest cavity.
Lumbar puncture (LUM-bar PUNK-chur)
A diagnostic procedure that involves removal of cerebrospinal fluid from the lumbar meningeal sac to assess the pressure and constituents of cerebrospinal fluid.
Lung abscess is a cavity within the lung parenchyma filled with necrotic tissues, which occurs as a result of tissue-destroying infaction.
The paired organs in the thoracic cavity in which gas exchange takes place between the air in the alveoli and the blood in the pulmonary capillaries.
Luteinizing hormone (LH or ICSH) (LOO-tee-in-EYEzing)
A gonadotropic hormone produced by the anterior pituitary gland that, in men, stimulates secretion of testosterone by the testes or, in women, stimulates ovulation and secretion of progesterone by the corpus luteum in the ovary.
Lymph node (LIMF NOHD)
A small mass of lymphatic tissue located along the pathway of a lymph vessel; produces some lymphocytes and destroys pathogens in the lymph.
Lymph nodule (LIMF NAHD-yool)
A small mass of lymphatic tissue located in a mucous membrane; destroys pathogens that penetrate mucous membranes.
Lymphatic tissue (lim-FAT-ik TISH-yoo)
A hemopoietic tissue that produces some lymphocytes and in which lymphocytes mature and are activated; found in the spleen and lymph nodes and nodules
A type of white blood cell (agranular); T cells and B cells are involved in the specific responses of adaptive immunity; natural killer cells are nonspecific and are part of innate immunity.
A cell organelle found in the cytoplasm; contains enzymes that digest damaged cell parts or material ingested by the cell.