Dictionary

Body systems

Anatomy and the conditions of each body system, from the heart and lungs to the skin.

libidoSexual desire: a person's interest in or drive toward sexual activity.

life spanThe whole length of a person's life, from conception or birth to death.

ligamentA tough band of tissue that connects one bone to another at a joint.

lipidA fat or fat-like substance in the body or food, such as cholesterol and triglycerides.

lipoproteinA particle made of fat and protein that carries cholesterol and other fats through the blood.

liverA large organ in the right upper abdomen that processes nutrients, makes bile and clotting factors, and clears drugs and toxins from the blood.

liver diseaseAny condition that damages the liver or keeps it from working normally.

lobeA rounded section or division of an organ, such as the brain, lung, liver or ear.

lochiaThe vaginal discharge of blood, mucus and tissue from the uterus after childbirth.

loop of HenleThe U-shaped part of each nephron in the kidney that helps decide how concentrated the urine is.

low back painPain in the lower part of the back, between the bottom of the ribs and the buttocks.

low-sodium dietAn eating plan that limits salt and other sources of sodium.

lower extremityThe leg, from the hip to the toes.

lumbarHaving to do with the lower back, the part of the spine between the ribs and the pelvis.

lumenThe open space inside a tube, such as a blood vessel, the intestine or a catheter.

lung cancerCancer that starts in the cells of the lungs.

lupusSystemic lupus erythematosus: a long-term autoimmune disease in which the immune system attacks the body's own tissues.

luteinizing hormoneA hormone from the pituitary gland that triggers ovulation in women and testosterone production in men.

Lyme diseaseAn infection with Borrelia bacteria, spread to people by the bite of an infected tick.

lymphThe clear fluid that flows through the lymphatic vessels and carries white blood cells.

lymph nodeA small, bean-shaped organ of the immune system that filters lymph fluid and holds white blood cells.

lymphadenopathySwollen or enlarged lymph nodes.

lymphaticRelating to lymph, the clear fluid that drains from body tissues, or to the vessels and nodes that carry it.

lymphatic systemThe network of lymph vessels, lymph nodes and organs such as the spleen and thymus that drains tissue fluid and helps fight infection.

lymphedemaSwelling of a body part from a buildup of lymph fluid in the tissues.

lymphocyteA type of white blood cell that targets specific germs and abnormal cells, including T cells, B cells and natural killer cells.

lymphomaA cancer of lymphocytes, the white blood cells of the lymph system.

macrophageA large white blood cell in the tissues that swallows and digests germs, dead cells and debris.

macular degenerationAn eye disease in which the macula, the center of the retina used for sharp, straight-ahead vision, slowly breaks down.

magnesium sulfate toxicityHarm from a blood magnesium level that rises too high, usually during magnesium sulfate treatment.

major depressive disorderA mental illness in which a person has a low mood or loses interest in almost everything for at least two weeks.

malformationA body part or organ that formed in an abnormal way before birth.

malignantCancerous: describing a tumor whose cells grow out of control, invade nearby tissue and can spread through the body.

malignant hyperthermiaA rare inherited reaction to certain general anesthesia drugs in which the muscles' metabolism speeds up out of control.

Mallory-Weiss tearA tear in the lining where the esophagus meets the stomach.

malnutritionPoor nutrition from too little, too much or the wrong balance of nutrients.

mandibleThe lower jawbone, the only bone of the skull that moves.

maniaA period of unusually high energy, mood and activity that is clearly different from the person's usual self.

marrowThe soft tissue inside bones; red marrow makes blood cells and yellow marrow stores fat.

mast cellAn immune cell in the tissues that releases histamine and other chemicals during allergic reactions and inflammation.

mastectomySurgery to remove all or part of a breast.

mastitisInflammation of the breast tissue, often with infection, most common in people who are breastfeeding.

maternalHaving to do with a mother, or with a woman during pregnancy, birth and the weeks after.

maturationThe process of becoming fully grown or developed.

McBurney pointA spot on the lower right abdomen about one-third of the way from the front of the hip bone to the navel.

mean arterial pressureThe average pressure in the arteries over one heartbeat, used as a measure of how well blood reaches the organs.

measlesA very contagious illness caused by the measles virus; also called rubeola.

meatusAn opening or passage in the body, such as the urinary opening or the ear canal.

mechanical ventilationBreathing support from a machine, a ventilator, that pushes air into the lungs through a tube or a mask.