Medical Glossary Index:

L

Labia- the two pairs of skinfolds that protect the opening of the vagina

Labor- the interval from onset of contractions to birth of a baby

Labyrinthitis- inflammation of the fluid-containing chamber of the inner ear
(called the labyrinth) that maintains balance; can cause a feeling that one's surroundings are spinning around (known as vertigo)

Laceration- a torn or ragged wound

Lactase deficiency- an inherited disorder in which a person does not have the enzyme lactase, which breaks down lactose (the sugar found in dairy products); lactase deficiency leads to lactose intolerance, which means the inability to digest lactose

Lactation- the production of breast milk after giving birth

Lactation suppression- a decrease in milk production during pregnancy as a result of high levels of estrogen in the blood

Lactic acid- an acid produced by glucose-burning cells when these cells have an insufficient supply of oxygen

Lactose- the sugar found in dairy products

Lactose intolerance- inability to break down and absorb the sugar lactose

Lamaze method- a method of preparing for childbirth that stresses physical conditioning, relaxation, and breathing exercises

Laminectomy- a surgical procedure that removes part of a vertebra to relieve pressure on the spinal cord or a nerve branching from the spinal cord

Laparoscope- a viewing instrument used to examine and treat disorders in the abdominal cavity; consists of a long tube with an eyepiece, a lens, and often a
camera, which allows the image to be viewed on a monitor

Laparoscopic cholecystectomy- surgical removal of the gallbladder using a laparoscope

Laparoscopy- a procedure done to examine the abdominal cavity using a laparoscope, usually to investigate pelvic pain or gynecologic conditions such as infertility

Large-cell carcinoma- one of the 4 major types of lung cancer

Large intestine- the part of the digestive tract that is located between the small intestine and the anus

Laryngectomy- surgical removal of all or part of the voice box (larynx) as a treatment for cancer

Laryngitis- inflammation of the voice box, usually caused by a viral infection; characterized by a hoarse voice

Larynx- the medical term for the voice box, the organ in the throat that produces voice and also prevents food from entering the airway

Laser treatment- the use of a laser (a concentrated beam of light) to perform medical procedures, such as the destruction of tumors

Latent infection- an infection that lies dormant in the body for months or years but can reappear

Lateral- on one side

Laxatives- drugs used to clear feces from the intestines; commonly used to treat constipation

Lazy eye- the common name for the visual defect resulting from untreated strabismus, in which the eyes are not correctly aligned

LDL- see Low-density lipoprotein

Lead poisoning- damage to the brain, nerves, red blood cells, or digestive system because of ingestion of lead

Learning disability- any of a variety of disorders, including hyperactivity, dyslexia, and hearing problems, that can interfere with a person's ability to learn

Legionnaires’ disease- a form of pneumonia that is mainly spread through air-conditioning systems and water

Leiomyoma- a noncancerous tumor of smooth muscle

Leishmaniasis- a group of parasitic diseases affecting the skin, mucous membranes, and internal organs; transmitted by the bite of a sandfly

Leptospirosis- infection by a spiral-shaped bacterium that affects the skin, eyes, muscles, kidneys, and liver; leptospirosis is carried by rodents

Lesch-Nyhan syndrome- a genetic disorder affecting only men that causes mental handicap, self-mutilation, and aggressive behavior

Lesion- an abnormality of structure or function in the body

Leukemia- a group of bone marrow cancers in which white blood cells divide uncontrollably, affecting the production of normal white blood cells, red blood cells, and platelets

Leukocyte- another name for a white blood cells

Leukocyte count- the number of white blood cells in the blood, which is used as a measure of health and possible infection

Leukodystrophy- a group of childhood genetic disorders in which the protective coverings of the nerves are destroyed

Leukoplakia- white patches that can develop in the mouth or on the penis or the opening of the vagina and are potentially cancerous

LH- see Luteinizing hormone

Lichen planus- a common skin disease in which itchy, small, pink or purple spots appear on the arms or legs

Ligament- a tough, elastic band of tissue that connects bones and suupports organs

Ligation- the process of closing a blood vessel or duct by tying it off

Lipid-lowering drugs- drugs taken to lower the levels of specific fats called lipids in the blood in order to reduce the risk of narrowing of the arteries

Lipidosis- any disorder in which fats cannot be properly broken down by the digestive system

Lipids- a group of fats stored in the body and used for energy

Lipoma- a noncancerous tumor of fatty tissue

Lipoproteins- substances containing lipids and proteins, comprising most fats in the blood

Liposarcoma- a cancerous tumor of fatty tissue

Liposuction- a surgical procedure in which fat is removed from areas of the body using a suction pump

Listeriosis- a rare bacterial infection acquired by eating undercooked infected meat or from infected live animals; can be dangerous to newborns and the elderly

Lithotripsy- a procedure done to break up stones in the urinary tract using ultrasonic shock waves, so that the fragments can be easily passed from the body

Liver- the largest organ in the body, producing many essential chemicals and regulating the levels of most vital substances in the blood

Liver failure- the final stage of liver disease, in which liver function becomes so impaired that other areas of the body are affected, most commonly the brain

Lobe- a well-defined, separate part of an organ

Lobectomy- surgical removal of a lobe

Local anesthesia- a method of preventing pain by inducing the loss of sensation in a certain area of the body while the patient remains awake

Locked joint- a joint that cannot be moved because of a disease or a lodged piece of bone or cartilage

Lockjaw- a spasm of the jaw muscles that prevents the mouth from opening,
such as that caused by tetanus

Locomotor system- the structures of the body that are responsible for its movement

Lordosis- the inward curvature of the spine at the lower back, which is normal
to a certain degree; abnormal as a result of certain medical conditions, being
overweight, or having muscle problems

Lou Gehrig's disease- see Amyotrophic lateral sclerosis

Low-density lipoprotein- a type of lipoprotein that is the major carrier of cholesterol in the blood, with high levels associated with narrowing of the arteries
and heart disease

Lumbago- dull, aching pain in the lower back

Lumbar puncture- a procedure in which a needle is inserted into the lower
region of the spinal canal to take out a sample of spinal fluid or to inject a drug

Lumbar spine- the lower part of the spine between the lowest pair of ribs and
the pelvis; made up of five vertebrae

Lumpectomy- surgical removal of a section of breast containing cancer

Lung collapse- a condition in which all or part of a lung cannot expand and fill with air

Lungs- two organs in the chest that take in oxygen from the air and release
carbon dioxide

Lupus erythematosus- a disorder of the immune system that causes
inflammation of connective tissue

Luteinizing hormone- a hormone produced by the pituitary gland that causes
the ovaries and testicles to release sex hormones and plays a role in the development of eggs and sperm

Lyme disease- a disease caused by bacteria transmitted through the bite of a
tick; characterized by fever, rash, and inflammation of the heart and joints

Lymph- a milky fluid containing white blood cells, proteins, and fats; plays an important role in absorbing fats from the intestine and in the functioning of the
immune system

Lymphadenopathy- swollen lymph nodes

Lymphangiography- an X-ray procedure that creates images of the lymphatic system

Lymphatic system- a network of vessels that drain lymph back into the blood

Lymph node- a small gland that is part of the immune system; contains white blood cells and antibodies and helps fight against the spread of infection

Lymphocyte- a white blood cell that is an important part of the body's immune system, helping to destroy invading microorganisms

Lymphocytic leukemia- a disease in which white blood cells called lymphocytes divide uncontrollably

Lymphogranuloma venereum- a sexually transmitted chlamydial infection; common in countries with a tropical climate

Lymphomas- a group of cancer of the lymph nodes and spleen that can spread to other parts of the body

Lymphosarcoma- another name for a non-Hodgkin's sarcoma; a cancerous tumor in lymphoid tissue