Dictionary

Body systems

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

laborThe process of childbirth, from the start of regular contractions that open the cervix to the delivery of the baby and placenta.

lacerationA cut or tear in the skin or other tissue, often with jagged edges.

lactationThe making and release of milk by the breasts.

lacticRelating to milk, or to lactic acid, a substance cells make when they break down glucose without enough oxygen.

lactic acidosisA type of metabolic acidosis in which lactic acid (lactate) builds up in the blood.

lanugoFine, soft, downy hair that covers the body of a fetus.

large for gestational ageDescribes a newborn who weighs more than 90 out of 100 babies born after the same number of weeks of pregnancy.

large intestineThe last part of the digestive tract, from the end of the small intestine to the anus, where water is absorbed and stool forms.

laryngitisInflammation of the larynx, the voice box.

laryngopharynxThe lowest part of the throat, below the back of the mouth, where the airway and the food passage separate.

larynxThe voice box: the part of the airway in the neck, above the windpipe, that holds the vocal cords.

last menstrual periodThe first day of a person's most recent menstrual period.

late decelerationA gradual drop in the fetal heart rate that starts and hits its lowest point after the peak of a contraction.

lateralToward the side of the body, away from the middle line.

latex allergyAn allergic reaction to proteins in natural rubber latex, found in some gloves, catheters and other products.

lead poisoningHarm to the body from a buildup of lead, a toxic metal, usually over months or years.

left lower quadrantThe lower left quarter of the abdomen, when it is divided into four parts by lines crossing at the navel.

left ventricleThe heart's lower left chamber, which pumps oxygen-rich blood into the aorta and out to the body.

left-sided heart failureHeart failure in which the left ventricle cannot pump enough blood out to the body.

lesionAn area of tissue that has been damaged or has changed from normal, such as a sore, wound, lump or spot.

letdownThe reflex that pushes milk out of the breast's milk glands toward the nipple during breastfeeding.

leukemiaA cancer of the blood-forming cells in the bone marrow, in which abnormal white blood cells are made in large numbers.

level of consciousnessHow awake, alert and aware of their surroundings a person is.

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.

limbAn arm or a leg.

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.