AMA Glossary of Medical Terms PDF

AMA Glossary of Medical Terms (Source: www.ama-assn.org ) A B C D E F G H I J K L M N O P Q R S T U V W X Y Z A Abdominal cavity- the part of the body between the bottom of the ribs and the top of the th...

AMA Glossary of Medical Terms (Source: www.ama-assn.org ) A B C D E F G H I J K L M N O P Q R S T U V W X Y Z A Abdominal cavity- the part of the body between the bottom of the ribs and the top of the thighs, containing most of the digestive and urinary systems along with some reproductive organs ABO blood groups- The system by which human blood is classified, based on proteins occurring on red blood cells; the four classification groups are A, AB, B, and O Abortion- termination of a pregnancy; can occur because of natural causes (called a miscarriage) or be a medical intervention Abscess- an accumulation of pus in a body tissue, usually caused by a bacterial infection ACE inhibitor- a drug typically used to treat high blood pressure (Angiotensin-Converting Enzyme inhibitor) Achilles tendon- the tendon at the back of the lower leg that connects the calf muscle to the heel bone Acid-base balance- the mechanisms that the body uses to keep its fluids close to neutral (neither basic nor acidic) so that the body can function properly Acidosis- a condition marked by abnormally high acid levels in the blood, associated with some forms of diabetes, lung disease, and severe kidney disease Acid reflux- a disorder in which acid in the stomach comes up into the esophagus, because the valve separating the stomach and esophagus does not function properly Acne- a skin condition characterized by inflamed, pus-filled areas that occur on the skin's surface, most commonly occurring during adolescence Acquired- a word describing any condition that is not present at birth, but develops some time during life Acquired immunodeficiency syndrome- infection by the human immunodeficiency virus (HIV), which causes a weakening of the immune system Acute- describes a condition or illness that begins suddenly and is usually short-lasting Acute respiratory disease- an urgent condition in which oxygen levels in the blood are lower than normal and breathing is difficult Addiction- dependence on a substance (such as alcohol or other drugs) or an activity, to the point that stopping is very difficult and causes severe physical and mental reactions Adenitis- infection and inflammation of a gland, especially a lymph node Adipose tissue- another term for fatty tissue; it stores energy, insulates, and cushions the body Adjuvant therapy- the use of drugs or radiation therapy in the treatment of cancer along with surgery Adrenal failure- a condition in which the adrenal glands do not produce enough of the hormones that control important functions such as blood pressure Adrenal glands- two small glands located on top of the kidneys that secrete several important hormones into the blood Adverse reaction- an unintended and unwanted side effect of some sort of treatment, usually drug therapy Aerobic exercise- physical activity during which the heart and lungs must work harder to meet the body's increased oxygen demand Affective disorder- a mental disorder involving abnormal moods and emotions; affective disorders include manic-depressive disorder Afterbirth- the placenta and membranes that are eliminated from the woman's uterus following the birth of a child Afterpains- normal contractions of the uterus after childbirth that usually occur for the first few days after delivery AIDS- see Acquired immunodeficiency syndrome AIDS-related complex- symptoms including weight loss, fever, and enlarged lymph nodes experienced by people who are infected with HIV but do not yet have AIDS Air embolism- the blockage of an artery by air bubbles, which may have entered during surgery or after an injury Airway obstruction- blockage of the passage of air through the windpipe to the lungs Airways- the passageways that air moves through while traveling in and out of the lungs during breathing Albinism- a condition in which people are born with insufficient amounts of the pigment melanin, which is responsible for hair, skin, and eye color Alcoholic cardiomyopathy- heart damage and failure caused by intake of too much alcohol Alimentary canal- another term for the digestive tract Alkalosis- dangerously decreased acidity of the blood, which can be caused by high altitudes, hyperventilation, and excessive vomiting Alkylating agents- substances used in cancer treatment that interfere with the division of cells Allergen- a substance that causes an allergic reaction Allergic rhinitis- irritation of the nasal passages and the whites of the eyes, causing sneezing, runny nose, and sore eyes Allergy- a negative reaction to a substance that in most people causes no reaction Alopecia- baldness or loss of hair, mainly on the head, either in defined patches or completely; the cause is unknown ALS- see Amyotrophic lateral sclerosis Altitude sickness- headaches, dizziness, and nausea usually experienced at heights above 8,000 ft because of reduced oxygen in the air Alzheimer disease- a condition that occurs late in life and worsens with time in which brain cells degenerate; it is accompanied by memory loss, physical decline, and confusion Amenorrhea- absence of menstrual periods, occurring either after or before menstruation has begun Amniocentesis- a procedure in which a small amount of amniotic fluid is removed from the mother’s womb in order to detect abnormalities of the fetus Amniotic fluid- clear fluid that surrounds a fetus during pregnancy and cushions and protects it Amyotrophic lateral sclerosis- the most common of a group of disorders known as motor neuron diseases, in which the nerves in the brain that control the movement of muscles degenerate and muscle function is gradually lost; commonly called Lou Gehrig's disease Anabolic steroid- a drug similar to the male hormone testosterone that builds muscles and strengthens bones, but has adverse side effects Anal fissure- a long, open sore on the skin of the anus Anal fistula- an abnormal tubelike passage connecting the anus to the surface of the surrounding skin Analgesic- a drug that relieves pain, such as aspirin or acetaminophen Anal sphincter- a ring of muscle fibers at the opening of the rectum, controlling the opening and closing of the anus Anaphylactic shock- a life-threatening allergic reaction resulting in difficulty breathing and low blood pressure Anatomy- the structure of bodies; commonly refers to the study of body structure Androgen- a hormone (such as testosterone) that causes development of male characteristics and sex organs Anemia- a condition in which the blood does not contain enough hemoglobin, the compound that carries oxygen from the lungs to other parts of the body Anencephaly- a fatal birth defect in which the brain and spinal cord have failed to develop, resulting in the absence of a portion of the skull and brain Anesthesia- a loss of sensation in a certain part of the body or throughout the body Anesthetic- a substance that temporarily causes a person to be unable to feel pain, either in a certain area or over the entire body Aneurysm- an abnormal swelling of the wall of an artery, caused by a weakening in the vessel wall Angina pectoris- pain experienced in the chest, arms, or jaw because of a lack of oxygen to the heart muscle Angioma- a tumor made of blood vessels or lymph vessels that is not cancerous Angioplasty- the use of surgery to make a damaged blood vessel function properly again; may involve widening or reconstructing the blood vessel Anorexia nervosa- a dangerous eating disorder mainly affecting young girls in which the sufferer has an intense fear of looking fat, avoids food, and loses weight excessively Antacid- a drug that neutralizes stomach acids; used to treat indigestion, heartburn, and acid reflux Antibiotic resistance- the development by bacteria of the ability to live in the presence of a certain antibiotic, making treatment difficult Antibiotics- bacteria-killing substances that are used to fight infection Antibody- a protein made by white blood cells that reacts with a specific foreign protein as part of the immune response Anticoagulants- drugs used to stop abnormal blood clotting, such as to prevent stroke Antiemetics- drugs used to treat nausea and vomiting Antihistamine- a drug that relieves an allergic reaction by stopping the effects of histamine, the substance responsible for the negative symptoms associated with the reaction Antihypertensives- drugs used to relieve the symptoms and prevent the damage that can occur from high blood pressure Antioxidants- substances that protect against cell damage by guarding the cell from oxygen free radicals Antipsychotics- drugs used to treat severe mental disorders Antiseptics- chemicals applied to the skin that prevent infection by killing bacteria and other harmful organisms Anus- the opening through which feces are passed from the body Aorta- the main artery in the body, carrying oxygenated blood from the heart to other arteries in the body Aortic stenosis- narrowing of the opening of the aortic valve in the heart, which increases resistance to blood flow from the left ventricle to the aorta; commonly a birth defect or caused by scarring and calcium accumulation in the valve from rheumatic fever Apgar score- a system for evaluating the health of a newborn baby; rated on a scale of 0- 10 Aplasia- the complete or partial failure of any organ or tissue to grow Aplastic anemia- a severely reduced number of red blood cells, white blood cells, and platelets Apnea- a possibly life-threatening condition in which breathing stops, for either a short or long period of time Appendectomy- surgical removal of the appendix to treat appendicitis Appendicitis- inflammation of the appendix Appendix- a short, tubelike structure that branches off the large intestine; does not have any known function ARC- see AIDS-related complex Arteriosclerosis- a disorder causing thickening and hardening of artery walls Arteritis- inflammation of the walls of an artery that causes the passageway to become narrower; can lead to tissue damage because oxygen is not properly supplied Artery- a large blood vessel that carries blood from the heart to tissues and organs in the body Arthritis- a disease of the joints characterized by inflammation, pain, stiffness, and redness Arthroscopy- a procedure used to examine the inside of a joint using a viewing tube (an endoscope) Artificial insemination- injection of semen into the cervix Artificial respiration/ventilation- the forcing of air (either by mouth-to-mouth or mouth- to-nose means) into the lungs of a person who has stopped breathing Ascites- excess fluid in the abdominal cavity, which leads to swelling Ascorbic acid- the chemical term for vitamin C Aspermia- the failure either to produce or to ejaculate sperm Asphyxia- the medical term for suffocation; can be caused by choking on an object, by lack of oxygen in the air, or by chemicals such as carbon monoxide, which reduce the amount of oxygen in the blood Asthma- a disorder characterized by inflamed airways and difficulty breathing Astigmatism- a disorder in which the front surface of the eye (the cornea) is not correctly spherical, resulting in blurry vision Atherectomy- a procedure performed to remove plaque that is blocking an artery Atheroma- fatty deposits on the inner walls of blood vessels, which can cause narrowing and decrease blood flow Atherosclerosis- narrowing of the lining of the arteries due to the accumulation of fat and other materials; leads to coronary heart disease, stroke, and other disorders Athlete's foot- an infection between the toes caused by a fungus, which leads to sore, cracked, and peeling skin Atresia- a birth defect in which a normal body opening or canal is absent; usually requires surgical repair soon after birth Atria- the two upper chambers of the heart; the singular form is atrium Atrial fibrillation- an irregular heartbeat in which the upper chambers of the heart (the atria) beat inconsistently and rapidly Atrial flutter- an irregular heartbeat in which the upper chambers of the heart (the atria) beat rapidly but consistently Atrial septal defect- a hole located in the wall between the two upper chambers of the heart Atrophy- the shrinkage or near disappearance of a tissue or organ Attention-deficit disorder- a disorder mainly present in children and adolescents, characterized by learning and behavior problems, inability to pay attention, and sometimes hyperactivity Audiogram- a graph showing a person's hearing ability, determined from a set of tests examining hearing acuity of different sound frequencies Aura- a "warning" signal that comes before a migraine headache or an epileptic seizure, which might include emotions or sensations of movement or discomfort Auscultation- the act of listening to sounds within the body, such as the heartbeat, with a stethoscope Autism- a mental disorder characterized by an inability to relate to other people and extreme withdrawal Autoimmune disease- a disorder in which the body’s immune system attacks itself Autonomic nervous system- the part of the nervous system that controls automatic body functions, such as heart rate, sweating, pupil dilation, and digestion; divided into the sympathetic nervous system and the parasympathetic nervous system Autopsy- the examination of a body following death, possibly to determine the cause of death or for research Autosomal dominant- a term describing a gene on any chromosome other than the sex chromosomes that produces its effect whenever it is present; can also describe the effect of the gene itself Autosomal recessive- a term used to describe a gene on any chromosome other than the sex chromosomes that produces its effect only when two copies of it are present; can also describe the effect of the gene itself Axilla- medical term for the armpit  B Bacillus- any bacteria that is rod-shaped; responsible for diphtheria, dysentery, tetanus, and tuberculosis, as well as other diseases Bacteremia- a condition in which bacteria are present in the bloodstream; may occur after minor surgery or infection and may be dangerous for people with a weakened immune system or abnormal heart valves Bacteriostatic- term used to describe a substance that stops the growth of bacteria (such as an antibiotic) Bacterium- a tiny, single-celled microorganism, commonly known as a germ; some bacteria, called pathogens, cause disease Bacteriuria- bacteria in the urine; large amounts can indicate bladder, urethra, or kidney infection Ball-and-socket joint- a joint consisting of a ball-shaped bone that fits into a cup-shaped bone, making the joint free to rotate; examples include the hip and shoulder Balloon angioplasty- a technique that uses a balloon catheter to open arteries clogged with fatty deposits Balloon catheter- a hollow tube with a small, inflatable balloon at the tip; used to open a narrowed artery or organ that has become blocked Barbiturates- a group of sedatives that reduce activity in the brain; are habit-forming and are possibly fatal when taken with alcohol Barium enema- a technique in which barium is placed into the large intestine and rectum and then X-rays are taken to check for possible disorders of these organs Barrier method of contraception- a birth-control technique using a condom, diaphragm, or another similar device to block the path of sperm to an egg Bartholin's glands- two pea-sized glands that, when sexually aroused, release a fluid that lubricates the vagina Basal cell carcinoma- a type of skin cancer that is caused by exposure to large amounts of sunlight; commonly found on the neck, face, and arms Basal metabolic rate- the lowest rate at which a person can possibly use energy and remain alive; at this rate, only absolutely necessary functions such as breathing are maintained B cell- a white blood cell that makes antibodies to fight infections caused by foreign proteins BCG vaccine- a vaccine used to protect against tuberculosis Becker’s muscular dystrophy- a hereditary disease in which the muscles weaken and waste away; similar to Duchenne muscular dystrophy but starts later in life and advances more slowly Bell's palsy- another name for facial palsy, the usually one-sided, temporary numbing of the facial muscles, caused by an inflamed nerve Bends- see Decompression sickness Benign tumor- a tumor that is not cancerous, which means it does not spread through the body, but may grow and become dangerous Beta blocker- a type of drug used to treat high blood pressure and heart disorders by reducing the strength and rate of the pumping by the heart Beta carotene- a pigment found in orange vegetables and fruits, which the body converts to vitamin A; possibly protects against cancer Bifocal- a lens that corrects both near and distant vision by having two parts with different focusing strengths Bilateral- a term describing a condition that affects both sides of the body or two paired organs, such as bilateral deafness (deafness in both ears) Bile- a yellow-green liquid produced in the liver whose function is to remove waste from the liver and break down fats as food is digested Bile duct- a tube that carries bile from the liver to the gallbladder and then to the small intestine Biliary atresia- a birth defect in which the bile ducts are not completely developed; often a liver transplant is necessary Biliary colic- a severe pain in the upper right section of the abdomen, usually caused by a gallstone passing out of the bladder or through the bile ducts Biliary tract- the system of organs and ducts through which bile is made and transported from the liver to the small intestine Bilirubin- the orange-yellow pigment in bile, causing jaundice if it builds up in the blood and skin; the levels of bilirubin in the blood are used to diagnose liver disease Binging and purging- behavior characteristic of the disorder bulimia in which a person overeats then rids themselves of the food before it can be absorbed by the body, either by forced vomiting or through the use of laxatives Biochemistry- the science that studies the chemistry of living organisms, including humans Bioequivalent- a drug that has the same effect on the body as another drug Biofeedback- a technique used to gain control over a function that is normally automatic (such as blood pressure or pulse rate); the function is monitored and relaxation techniques are used to change it to a desired level Bipolar disorder- an illness in which the patient goes back and forth between opposite extremes; the most notable bipolar disorder is manic-depressive disorder, which is characterized by extreme highs and lows in mood Birth canal- the passage that includes the uterus and vagina through which the baby passes at birth Birth control- the regulation of the number of children born, referring either to the prevention of pregnancy (by birth control pill, sterilization, etc) or the prevention of birth (by abortion, etc) Birth defect- an abnormality that is present when a baby is born Birthmark- any area of discolored skin that is present when a baby is born Bisexuality- sexual interest in members of both sexes Bladder- an organ located in the pelvis whose function is to collect and store urine until it is expelled Blepharitis- inflammation of the eyelids Blind spot- a spot in the field of vision that is not sensitive to light; it is a product of the entrance of the optic nerve into the eyeball, where no light receptors are present on the retina Blood-brain barrier- a layer of tightly bound cells that prevents certain substances carried in the bloodstream from entering the brain Blood clot- a semisolid mass of blood that forms to help seal and prevent bleeding from a damaged vessel Blood poisoning- see Septicemia Blood pressure- the tension in the main arteries that is created by the beating of the heart and the resistance to flow and elasticity of the blood vessels Blood transfusion- the transfer of blood or any of its parts to a person who has lost blood due to an injury, disease, or operation Blood type- a category used to describe a person's blood according to the kinds of proteins present on the surface of the red blood cells B lymphocyte- a type of white blood cell that makes antibodies and is an important part of the immune response Boil- an inflamed, raised area of skin that is pus-filled; usually an infected hair follicle Bone marrow- the fatty yellow or red tissue inside bones that is responsible for producing blood cells Bone marrow transplant- a surgical procedure in which defective or cancerous bone marrow is replaced with healthy marrow, either from the patient or a donor Bone spur- an abnormal growth of bone out of another bone, often located on the heel and usually painful Booster- an additional dose of a vaccine taken after the first dose to maintain or renew the first one Botulism- poisoning from poorly preserved food contaminated with a dangerous bacterial toxin that results in paralysis Bowel- see Intestine Bradycardia- a slow heart rate, usually below 60 beats per minute in adults Brain damage- permanent death or damage of brain cells resulting in decreased mental ability Brain death- the condition in which the brain stops functioning while the heart continues to beat Breech birth- childbirth in which the baby is turned around in the uterus and emerges head-last instead of head-first Bronchiolitis- an infection caused by a virus in the bronchioles (the smallest airways in the lungs), mainly affecting young children Bronchitis- inflammation of the bronchial tubes, which connect the trachea to the lungs Bronchoconstrictor- a substance that causes the lung airways to tighten up and become more narrow Bronchodilator- a drug that widens the airways in the lungs to improve breathing; works by relieving muscle contraction or buildup of mucus Bronchospasm- the temporary narrowing of the airways in the lungs, either as a result of muscle contraction or inflammation; may be caused by asthma, infection, lung disease, or an allergic reaction Bruise- see Contusion Bruxism- an unaware clenching or grinding of the teeth, usually during sleep Bubonic plague- a form of plague in which lymph nodes in the groin and armpit swell Bulimia- a disorder in which a person eats large amounts of food then forces vomiting or uses laxatives to prevent weight gain (called binging and purging) Bunion- a hard, fluid-filled pad along the inside joint of the big toe; may be caused by wearing high-heeled shoes or a genetically weak joint Burkitt's lymphoma- a cancer of lymph tissue that most frequently occurs in the abdomen, the ovaries, and the bones of the face; it is associated with malaria Bursa- a fluid-filled sac that cushions and reduces friction in certain parts of the body Bursitis- inflammation of a bursa due to excessive pressure or friction, or from injury Butterfly bandage- a butterfly-shaped bandage that can help close a minor cut for proper healing Bypass- a surgical technique in which the flow of blood or another body fluid is redirected around a blockage  C Calcification- the depositing of calcium salts in the body, which occurs normally in teeth and bones but abnormally in injured muscles and narrowed arteries Calcitonin- a hormone made in the thyroid gland that controls calcium levels in the blood by slowing the loss of calcium from bones; used to treat hypercalcemia (excess calcium in the blood) Calcium- a plentiful mineral in the body and the basic component of teeth and bones; essential for cell function, muscle contraction, transmission of nerve impulses, and blood clotting Calcium channel blocker- a drug used to treat chest pain, high blood pressure, and irregular heartbeat by preventing the movement of calcium into the muscle Callus- a thickened area of skin due to consistent pressure or friction, or the area around a bone break where new bone is formed Calorie- a unit that is used to measure the energy content in food Canal- a tunnel-like passage Cancer- a group of diseases in which cells grow unrestrained in an organ or tissue in the body; can spread to tissues around it and destroy them or be transported through blood or lymph pathways to other parts of the body Cancer staging- a method to determine how much a cancer has developed Candidiasis- a yeast infection caused by the fungus Candida albicans; occurs most often in the vagina, but also in the mouth, on moist skin, or on the penis Canker sore- small, painful sore that usually occurs on the inside of the lip or cheek, or sometimes under the tongue; caused by bacteria, irritation of the area, stress, or allergies Capillary- a tiny blood vessel that connects the smallest arteries to the smallest veins and allows exchange of oxygen and other materials between blood cells and body tissue cells Carbohydrate- a substance, mainly sugar and starch, that is a main source of energy for the body and is found in sources such as cereals, breads, pastas, grains, and vegetables Carbon dioxide- a colorless, odorless gas present in small amounts in the atmosphere and formed during respiration Carcinogen- anything that can cause cancer Carcinoma- a cancer that occurs on the surface or lining of an organ Cardiac arrest- the sudden cessation of the heart's pumping action, possibly due to a heart attack, respiratory arrest, electrical shock, extreme cold, blood loss, drug overdose, or a severe allergic reaction Cardiogenic shock- a severely dangerous condition involving decreased blood output from the heart, usually as a result of a heart attack Cardiomegaly- a condition marked by enlargement of the heart, either because of a thickened heart muscle or an enlarged heart chamber; usually a result of the heart having to work harder than normal, as occurs with high blood pressure Cardiomyopathy- a disease of the heart muscle that results in decreased output and reduced blood flow Cardiopulmonary resuscitation- the administration of heart compression and artificial respiration to restore circulation and breathing Cardiovascular system- the heart and blood vessels that are responsible for circulating blood throughout the body Carditis- inflammation of the heart Carotene- an orange pigment present in colored plants such as carrots that is converted by the body to the essential nutrient vitamin A Carotid arteries- four main arteries that carry blood to the head and neck Carpal bones- eight bones that together make the wrist Carpal tunnel syndrome- a condition in which pressure on the median nerve in the wrist causes soreness, tingling, and numbness in the thumb and index and middle fingers Cartilage- a connective tissue (softer than bone) that is part of the skeletal system, including the joints Cast- a hard plaster or fiberglass shell that molds to a body part such as an arm and holds it in place for proper healing Cataract- a disorder in which the lens of the eye becomes less transparent and in some cases a milky white, making vision less clear Catheter- a hollow, flexible tube inserted into the body to put in or take out fluid, or to open up or close blood vessels Catheterization- a technique in which a hollow, flexible tube is used to drain body fluids (such as urine), to introduce fluids into the body, or to examine or widen a narrowed vein or artery CAT scanning- see Computed tomography scanning Cat-scratch fever- an illness transmitted to humans through a cat's bite or scratch, which is thought to be caused by an unidentified bacteria; characterized by a swollen lymph node or blister near the bite or scratch, fever, rash, and headache; most commonly occurring in children Cauliflower ear- a deformed ear caused by repeated injury Cauterization- the use of heat, an electric current, or a chemical to destroy tissue or stop bleeding Cecum- the beginning of the large intestine, which is connected to the appendix at its lower end Cell- the tiny structures that make up all the tissues of the body and carry out all of its functions Cellulitis- a skin infection caused by bacteria (usually streptococci); can lead to tissue damage and blood poisoning if untreated; characterized by fever, chills, heat, tenderness, and redness Central nervous system- the brain and spinal cord Cerebellum- a region of the brain located at the back; responsible for coordination of movement and maintaining balance Cerebral palsy- a group of disorders of movement and posture resulting from damage to the brain early in a child's development; causes muscle weakness, difficulty coordinating voluntary movements, and sometimes complete loss of motion Cerebrospinal fluid- a clear, watery fluid circulating in and around the brain and spinal column, which contains glucose, proteins, and salts for nutrition Cerebrovascular disease- a disease affecting any artery supplying blood to the brain; may cause blockage or rupture of a blood vessel, leading to a stroke Cerebrum- the largest part of the brain and the site of most of its activity, including sensory and motor functions Cervical cap- a small rubber cup that is placed tightly over the cervix to prevent pregnancy Cervical dysplasia- changes that occur in the cells on the surface of the cervix that usually precede the stages of cancer Cervical incompetence- a weakness of the neck of the uterus, which can lead to spontaneous abortion due to an inability to support the weight of the fetus Cervical smear- a procedure in which cells are scraped off of the cervix and examined to detect changes that might precede the stages of cancer; also called a Pap smear Cervicitis- inflammation of the cervix Cervix- a small, round organ making up the neck of the uterus and separating it from the vagina Cesarean section- an operation performed to remove a fetus by cutting into the uterus, usually through the abdominal wall Chancre- a painless sore that has a thick, rubbery base and a defined edge; usually occurs on the genitals after the contraction of the sexually transmitted disease syphilis Chemotherapy- the treatment of infections or cancer with drugs that act on disease- producing organisms or cancerous tissue; may also affect normal cells Chickenpox- a contagious disease that causes a rash and a fever; most commonly occurs during childhood Chlamydia- microorganisms that cause several human infections and can be transmitted sexually Cholecystectomy- the surgical removal of the gallbladder Cholera- a bacterial infection of the small intestine that causes severe watery diarrhea, dehydration, and possibly death Cholesterol- a substance in body cells that plays a role in the production of hormones and bile salts and in the transport of fats in the bloodstream Chondritis- inflammation of cartilage Chondroma- a noncancerous tumor that occurs in cartilage Chondromalacia patellae- painful damage to the cartilage behind the kneecap Chondrosarcoma- a cancerous cartilage tumor that develops inside of bone or on its surface Chorionic villus sampling- a method of diagnosing fetal defects in which a small amount of tissue is taken from the placenta and analyzed for abnormalities Choroiditis- inflammation of the blood vessels behind the retina that line the back of the eye Chromosome analysis- examination of a person’s chromosomes either to determine if that person has an abnormality or to investigate one Chronic- describes a disorder that continues for a long period of time Chronic obstructive lung disease- a combination of the lung diseases emphysema and bronchitis, characterized by blockage of airflow in and out of the lungs Cilia- tiny, hairlike structures on the outside of some cells, providing mobility Circumcision- the surgical removal of the foreskin of the penis Cirrhosis of the liver- gradual loss of liver function due to cell damage and internal scarring Claudication- a cramping pain in one or both legs while walking, which can cause limping Claustrophobia- fear of being confined in an enclosed or crowded space Clavicle- the medical term for the collarbone Cleft lip- a birth defect in which the upper lip is split vertically, extending into one or both nostrils Cleft palate- a birth defect in which the roof of the mouth is split, extending from behind the teeth to the nasal cavity; often occurs with other birth defects such as cleft lip and partial deafness Clinical trial- carefully monitored and planned testing of a new drug or treatment Clitoris- a small female organ located near the opening of the vagina that swells when sexually aroused Clone- an exact copy of a gene, cell, or organism Closed fracture- a bone break that does not break the skin Clotting factor- a substance in the blood that is needed for blood to harden and stop a wound from bleeding Clubfoot- a genetic disorder in which the foot is twisted and misshapen Cluster headache- severe pain that occurs suddenly and affects one side of the head, including the face and neck CNS- see Central nervous system Coagulation- a process that plays a large role in the hardening and thickening of blood to form a clot Cocarcinogen- a substance that does not cause cancer by itself, but increases the effect of a substance that does cause cancer Coccyx- four fused bones that form a triangular shape at the base of the spine (also known as the tailbone) Cochlea- a coiled organ in the inner ear that plays a large role in hearing by picking up sound vibrations and transmitting them as electrical signals Coitus- sexual intercourse Cold sore- a small blister anywhere around the mouth that is caused by the herpes simplex virus Colectomy- the complete or partial surgical removal of the large intestine (the colon), usually as treatment of a cancerous tumor or a narrowing and blockage of the intestine Colic- waves of pain in the abdomen that increase in strength, disappear, and return; usually caused by a stone blocking a bile or urine passageway or an intestinal infection Colitis- inflammation of the large intestine (the colon), which usually leads to abdominal pain, fever, and diarrhea with blood and mucus Collapsed lung- a condition in which all or part of a lung cannot expand and fill with air Colon- the main part of the large intestine, between the cecum and the rectum Colonoscopy- investigation of the inside of the colon using a long, flexible fiberoptic tube Color blindness- any vision disorder in which the person sees colors abnormally, has trouble distinguishing between them, or cannot see them at all Colostomy- a surgical procedure in which some part of the colon is cut and moved to the surface of the abdomen so that feces can be passed into a bag worn outside of the body Coma- a condition in which the area of the brain involved in maintaining consciousness is somehow affected, resulting in a state of unconsciousness in which the patient does not respond to stimulation Comminuted fracture- a crushed or shattered bone Common cold- an infection caused by a virus, which results in an inflamed lining of the nose and throat; characterized by a stuffy and runny nose and, sometimes, a sore throat Communicable disease- a disease that can be passed from one individual to another Compound fracture- a bone break that breaks the skin Compression fracture- a break in a short bone in which its soft tissue is crushed Computed tomography scanning- a technique for producing cross-sectional images of the body in which X-rays are passed through the body at different angles and analyzed by a computer; also called CT scanning or CAT scanning Concussion- disturbance of electrical activity in the brain due to a blow to the head or neck, causing temporary loss of consciousness Congenital- present or existing at the time of birth Congestive heart failure- inability of the heart to efficiently pump blood through the body, causing buildup of blood in the veins and of other body fluids in tissue Conjunctiva- the clear membrane covering the white of the eye and the inside of the eyelid that produces a fluid that lubricates the cornea and eyelid Conjunctivitis- inflammation of the conjunctiva; commonly called pinkeye Connective tissue- strong tissue that connects and supports body structures Constipation- difficult or infrequent bowel movements of hard, dry feces Contraindication- an aspect of a patient's condition that makes the use of a certain drug or therapy an unwise or dangerous decision Contusion- damage to the skin and underlying tissue as a result of a blunt injury; a bruise Corn- a thickened callus on the foot that is caused by an improperly fitting shoe Cornea- the clear, dome-shaped front portion of the eye’s outer covering Coronary- describes structures that encircle another structure (such as the coronary arteries, which circle the heart); commonly used to refer to a coronary thrombosis or a heart attack Coronary arteries- the arteries that branch off from the aorta and supply oxygen-rich blood to the heart muscle Coronary artery bypass surgery- an operation in which a piece of vein or artery is used to bypass a blockage in a coronary artery; performed to prevent myocardial infarction and relieve angina pectoris Coronary heart disease- disorders that restrict the blood supply to the heart, including atherosclerosis Coronary thrombosis- the blockage of a coronary artery by a blood clot Corpuscle- a tiny, rounded structure in the body, such as a red or white blood cell Corticosteroids- synthetic drugs that are used to replace natural hormones or to suppress the immune system and help prevent inflammation CPR- see Cardiopulmonary resuscitation Creatinine- a waste product that is filtered from the blood by the kidneys and expelled in urine Croup- a usually mild and temporary condition common in children under the age of 4 in which the walls of the airways become inflamed and narrow, resulting in wheezing and coughing Cruciate ligaments- two ligaments in the knee that cross each other and help stabilize the knee joint CT scanning- a procedure that uses X-rays and computers to create cross-sectional images of the body to diagnose and monitor disease Culture- the artificial growth of cells, tissue, or microorganisms such as bacteria in a laboratory Curettage- the use of a sharp, spoonlike instrument (a curet) to scrape away tissue that is abnormal or to obtain a sample that can be analyzed CVS- see Chorionic villus sampling Cyanosis- a bluish discoloration of the skin, caused by low levels of oxygen in the blood Cyst- a lump filled with either fluid or soft material, occurring in any organ or tissue; may occur for a number of reasons but is usually harmless unless its presence disrupts organ or tissue function Cystectomy- surgical removal of the bladder; the bladder is often replaced with a short length of small intestine Cystic fibrosis- an inherited disorder in which the lungs are prone to infection, and fats and other nutrients cannot be absorbed into the body Cystoscopy- examination of the urethra and bladder using a long, thin, fiberoptic tube Cystostomy- the surgical placement of a drainage opening in the bladder  D D and C- see Dilatation and Curettage Debridement- surgical removal of dead, damaged, or infected tissue, or some foreign material from a wound or burn Decompression sickness- the formation of gas bubbles in the body’s tissues as a result of a scuba diver ascending too quickly from depth; commonly called the bends Deep-vein thrombosis- the formation of a blood clot inside of a deep-lying vein, usually in the legs Defecation- the passing of feces out of the body through the anus; a bowel movement Defibrillation- a short electric shock to the chest to normalize an irregular heartbeat Degenerative arthritis- the breakdown of the cartilage lining the bones in joints, usually weight-bearing joints (such as the knee); causes stiffness and pain (also called osteoarthritis) Dehydration- excessive, dangerous loss of water from the body Dementia- a gradual decline in mental ability usually caused by a brain disease, such as Alzheimer disease Depilatory- a chemical hair remover Depot injection- injection of a drug into a muscle; the drug is designed to absorb slowly into the body Depression- feelings of hopelessness, sadness, and a general disinterest in life, which for the most part have no cause and may be the result of a psychiatric illness Dermabrasion- removal of the surface layer of skin with a sanding wheel to treat scarring or to remove tattoos Dermatitis- inflammation of the skin Dermis- the inner skin layer Desensitization- the process of making a person less allergic to a substance by injecting gradually increasing amounts of the substance; sometimes done to prevent anaphylactic shock Detoxification- treatment given either to fight a person's dependence on alcohol or other drugs or to rid the body of a poisonous substance and its effects Dextrocardia- a rare genetic condition in which the heart is located on the right side of the body, instead of the left Dextrose- another name for the sugar glucose Diabetes insipidus- a rare condition characterized by increased urine production Diabetes mellitus- a common form of diabetes in which the body cannot properly store or use glucose (sugar), the body's main source of energy Dialysis- a procedure to treat kidney failure in which artificial means are used to filter waste, maintain acid-base balance, and remove excess fluid from the body Diaper rash- a common condition in babies in which the skin in the diaper area becomes irritated and red, usually because of exposure to urine, feces, or heat Diaphragm- the large, dome-shaped muscle separating the abdomen and chest that contracts and relaxes to make breathing possible; also, a thin, rubber dome that is used as a method of female contraception Diastolic pressure- the blood pressure measured when the heart is at rest between beats Diathermy- the use of high-frequency currents, microwaves, or ultrasound to produce heat in the body to increase blood flow, relieve pain, or destroy diseased tissue Dilatation and Curettage- a procedure in which the vagina and cervix are widened and the lining of the uterus is scraped away to diagnose and treat disorders of the uterus Diphtheria- a bacterial infection that causes a fever, headache, sore throat, and possibly death; diphtheria is rare in developed countries Disk prolapse- a disorder in which one of the disks located between the vertebrae in the spine breaks down and the pulpy interior squeezes out, causing pressure on a nerve; commonly called a "slipped" or "ruptured" disk Dislocation- displacement of the two bones in a joint Distention- swelling, enlargement, or stretching Diuretic- a drug that increases the amount of water in the urine, removing excess water from the body; used in treating high blood pressure and fluid retention Diverticulitis- inflammation of diverticula (small sacs in the intestine's inner lining); can cause fever, pain, and tenderness DNA- deoxyribonucleic acid; responsible for passing genetic information in nearly all organisms Dominant gene- a gene that always produces its effect when it is present Dopamine- a chemical that transmits messages in the brain and plays a role in movement Down syndrome- a genetic disorder in which a person’s cells have 1 too many chromosomes, causing moderate to severe mental handicap and a characteristic appearance Duchenne muscular dystrophy- a genetic condition in boys in which nerves degenerate and muscles get progressively weaker Duodenal ulcer- an erosion in the inner lining of the wall of the first part of the small intestine (called the duodenum) Duodenum- the first part of the small intestine, immediately following the stomach Dysentery- a severe intestinal infection, causing abdominal pain and diarrhea with blood or mucus Dyspnea- difficulty breathing Dystrophy- any disorder in which cells become damaged or do not develop properly because they do not receive adequate nutrition  E Eardrum- a thin, oval-shaped membrane that separates the inner ear from the outer ear and is responsible for transmitting sound waves ECG (sometimes called an EKG)- an electrocardiogram, which is a record of the electrical impulses that trigger the heartbeat; used to diagnose heart disorders Echocardiogram- an image of the heart that is created by high-frequency (ultrasound) sound waves Eclampsia- a serious condition that occurs in late pregnancy, characterized by seizures in the woman Ectopic- occurring at an abnormal position or time Eczema- inflammation of the skin, usually causing itchiness and sometimes blisters and scaling; may be caused by allergies, but often occurs for no apparent reason Edema- abnormal buildup of fluid in the body, which may cause visible swelling EEG- see Electroencephalography Elective- describes a treatment or procedure that is not urgent and can be arranged at the patient’s convenience Electroencephalography- a procedure for recording the electrical impulses of brain activity Embolism- the blockage of a blood vessel by an embolus - something previously circulating in the blood (such as a blood clot, gas bubble, tissue, bacteria, bone marrow, cholesterol, fat, etc) Embryo- a term used to describe a child in the womb from fertilization to 8 weeks following fertilization Emetic- a substance that causes vomiting; used to treat some cases of poisoning and drug overdose Emphysema- a chronic disease in which the small air sacs in the lungs (the alveoli) become damaged; characterized by difficulty breathing Encephalitis- inflammation of the brain, usually caused by a virus; may be very mild and barely noticeable, but is usually serious and can progress from headache and fever to hallucinations, paralysis, and sometimes coma Endarterectomy- surgery performed to remove the lining of an artery that has been narrowed by fatty tissue buildup Endemic- describes a disease that is always present in a certain population of people Endocarditis- inflammation of the inner lining of the heart, usually the heart valves; typically caused by an infection Endocardium- the inner lining of the heart Endocrine gland- a gland that secretes hormones into the bloodstream Endogenous- arising from inside of the body Endometrial polyp- a growth (usually noncancerous) occurring on the lining of the uterus Endometriosis- a condition in which fragments of the endometrium are found in other pelvic organs Endometrium- the membrane that lines the uterus Endophthalmitis- inflammation of the inside of the eye Endorphin- a group of chemicals produced in the brain that reduce pain and positively affect mood Endoscope- a lighted instrument used to view the inside of a body cavity Endothelium- the layer of flat cells that lines the blood and lymph vessels, the heart, and other structures in the body Endotracheal tube- a plastic tube that is fed down into the trachea through the mouth or nose to supply oxygen to a person who is not breathing properly Enteritis- inflammation of the small intestine, usually causing diarrhea Enterobiasis- infestation by a pinworm Enuresis- the medical term for wetting the bed Enzyme- a chemical, originating in a cell, that regulates reactions in the body Epidemic- a term used to describe a disease that is rare then suddenly affects more people than usually expected Epidermis- the outer layer of the skin Epididymis- a long, coiled tube, exiting from the back of the testicle, in which sperm mature Epidural anesthesia- a method of pain relief in which a painkilling drug is injected into the space surrounding the spinal cord to block sensations in the abdomen and lower body Epilepsy- a disorder of the nervous system in which abnormal electrical activity in the brain causes seizures Epinephrine- a hormone produced by the adrenal glands in response to stress, exercise, or fear; increases heart rate and opens airways to improve breathing; also called adrenaline Episcleritis- a patch of inflammation on the outer layer of the white of the eye Episiotomy- a surgical procedure in which an incision is made in the tissue between the vagina and anus to prevent tearing of this tissue during childbirth Epithelium- the layer of cells that covers the body and lines many organs Epstein-Barr virus- a virus that is the cause of mononucleosis and is involved in Burkitt’s lymphoma Erysipelas- an infection caused by streptococci bacteria; characterized by fever and rash Erythema- redness of the skin Erythrocyte- a red blood cell Erythrocyte sedimentation rate- a measure of the time it takes for red blood cells to collect at the bottom of a sample of blood; an elevated rate may mean that there is inflammation somewhere in the body Erythroplakia- red patches in the mucous membranes of the mouth, throat, or voice box (larynx) that can become cancerous; risk factors include smoking pipes and chewing tobacco Esophageal spasm- irregular contractions of the muscles in the esophagus, which lead to difficulty swallowing Esophageal varices- swollen veins in the lower esophagus and possibly the upper part of the stomach; can cause vomiting of blood and passing of black stool Esophagus- a tube-shaped canal in the digestive tract, connecting the throat to the stomach Estrogen- a group of hormones (produced mainly in the ovaries) that are necessary for female sexual development and reproductive functioning Estrogen replacement therapy- treatment with synthetic estrogen drugs to relieve symptoms of menopause and to help protect women against osteoporosis and heart disease Eustachian tube- the tube that connects the middle ear and the back of the nose, draining the middle ear and regulating air pressure Euthanasia- painlessly ending the life of a patient with an incurable disease who requests to die Excision- the surgical removal of diseased tissue Excretion- the process by which the body rids itself of waste Exercise stress test- the monitoring of the heart during strenuous exercise, usually on a treadmill or exercise bicycle, to evaluate how the heart responds to stress Exercise thallium test- an imaging test performed during and after an exercise stress test to evaluate functioning of the heart muscles Exogenous- arising from outside of the body Expectorant- a medication used to promote the coughing up of phlegm from the respiratory tract Extensor muscle- a muscle that causes a joint or limb to straighten External version- external repositioning of the fetus in the womb to the correct birth position Extracorporeal shock wave lithotripsy- a procedure performed to destroy kidney stones using external shock waves Extradural anesthesia- injection of an anesthetic into the space outside the dura mater, the fibrous membrane that envelops the spinal cord  F Facial palsy- inability to move the muscles of the face, usually on only one side, due to inflammation of a nerve Failure to thrive- describes a baby who grows and gains weight slower than expected Fallopian tube- either of two long, slender ducts connecting a woman's uterus to her ovaries, where eggs are transported from the ovaries to the uterus and sperm may fertilize an egg Familial- a term describing a disorder or characteristic (such as male pattern baldness) that occurs within a family more often than would be expected Fasciitis- inflammation of the layer of connective tissue that covers, separates, and supports muscles Fatty acid- any of a number of carbon-, oxygen-, and hydrogen-containing molecules that make up fats Febrile- a term used to describe something related to a fever, such as febrile seizures (seizures occurring in a child who has a fever) Fecal occult blood test- a test that uses a piece of chemically sensitive paper to detect blood in a stool sample; used to screen for possible signs of cancer in the large intestine or rectum Femoral artery- the main artery that supplies blood to the leg Femur- the bone located between the hip and the knee; the thighbone Fertility- the ability to produce a child Fertility drug- a drug used to treat infertility that contains hormones or substances associated with hormones Fertilization- the joining of an egg and a sperm, creating the first cell of a new life Fetal alcohol syndrome- a combination of defects in a fetus as a result of the mother drinking alcohol during pregnancy Fetal distress- physical distress experiencd by a fetus because of lack of oxygen Fetal monitoring- the use of an instrument to record or listen to a fetus' heartbeat during pregnancy and labor Fetal tissue transplant- an experimental procedure in which cells are taken from an aborted fetus and placed into the brain of a person with a brain disease such as Parkinson's Fetus- the term used to refer to an unborn child from 8 weeks after fertilization to birth Fiber- a constituent of plants that cannot be digested, which helps maintain healthy functioning of the bowels Fiberoptics- thin, flexible instruments that transmit light and images, allowing structures inside of the body to be viewed Fibrillation- rapid, inefficient contraction of muscle fibers of the heart caused by disruption of nerve impulses Fibroadenoma- a noncancerous tumor commonly found in the breast Fibrocystic breast disease- the most common cause of breast lumps Fibroid- a noncancerous tumor of the uterus made up of smooth muscle and connective tissue Fibroma- a noncancerous tumor of connective tissue Fibrosis- abnormal formation of connective or scar tissue Fifth disease- a childhood infection caused by a virus, which often starts as a rash on the cheeks and spreads Fissure- a groove or slit on the body or in an organ Fistula- an abnormal passageway from one organ to another or from an organ to the body surface Fitness- a measure of a person's physical strength, flexibility, and endurance Flatulence- excessive air or gas in the intestines, which is expelled through the anus Floaters- small spots that float across the field of vision, caused by debris floating in the gel-like substance that fills the eye Flu- see Influenza Fluke- a parasitic flatworm that can infest humans Fluoride- a mineral that helps protect teeth against decay Fluoroscopy- a method used to view organ structure and function by passing X-rays through the body and monitoring the resulting image on a fluorescent screen Folic acid- a vitamin essential to the production of red blood cells; plays an important role in the growth a developing fetus Follicle- a tiny pouchlike cavity in a structure of the body, such as a hair follicle Follicle stimulating hormone- a hormone produced by the pituitary gland in the brain that stimulates the testicles to produce sperm in males and causes eggs to mature in females Folliculitis- the inflammation of hair follicles due to a bacterial infection, causing boils or tiny blisters containing pus Fontanelles- the two soft spots on a baby’s scalp that are the result of gaps in the skull where bones have not yet fused Food poisoning- stomach pain, diarrhea, and/or vomiting caused by eating contaminated food Forceps- instruments resembling tweezers that are used to handle objects or tissue during surgery Forceps delivery- the use of an instrument that cups the baby's head (called an obstetric forceps), to help deliver a baby Foreign body- an object in an organ or body cavity that is not normally present Foreskin- the loose skin that covers the head of the penis Fracture- a bone break Fraternal twins- twins that develop from two different eggs fertilized by two different sperm; are not identical Free radical- see Oxygen free radical Frostbite- damage to body tissue as a result of freezing FSH- see Follicle stimulating hormone Fulminant- describes a disorder that begins suddenly and worsens quickly Fungus- an organism that is dependent on another organism for nourishment  G Galactocele- a milk-filled tumor in a blocked breast milk duct Galactorrhea- breast milk production by a woman who is not pregnant and has not just given birth Galactose- a sugar that is formed from the breakdown of lactose Galactosemia- a genetic disorder in which galactose cannot be converted into glucose Gallbladder- a small, pear-shaped sac positioned under the liver, which concentrates and stores bile Gallstone- a round, hard mass of cholesterol, bile, or calcium salts that is found in the gallbladder or a bile duct Gallstone ileus- an abnormal condition in which a gallstone passes from the gallbladder into the intestines through an abnormal passage and blocks the intestine Gamete intrafallopian transfer- a method of treating infertility in which eggs are taken from a woman's ovaries and fertilized with sperm and then the fertilized egg is injected into one of her fallopian tubes Gamma globulin- a substance prepared from blood that carries antibodies to most common infections; also used in immunizations Ganglion- a fluid-filled cyst attached to a tendon sheath or joint Gangrene- death of a tissue because of a lack of blood supply Gastrectomy- surgical removal of all or part of the stomach Gastric acid- the digestive acid in the stomach Gastric juice- digestive fluids produced by the lining of the stomach that break down proteins and destroy harmful organisms Gastric lavage- washing out of the stomach with water, often to treat poisoning; commonly called "stomach pumping" Gastric ulcer- a peptic ulcer Gastrin- a hormone that stimulates the release of gastric acid in the stomach Gastrinoma- a tumor that produces gastrin, making the stomach and duodenum more acidic Gastritis- inflammation of the mucous membrane lining of the stomach; can have a number of causes, including viruses, bacteria, and use of alcohol and other drugs Gastroenteritis- inflammation of the stomach and intestines Gastrointestinal series- a set of X-rays, taken at different intervals after a barium sulfate solution is swallowed, to examine the gastrointestinal tract Gastrointestinal tract- the part of the digestive system that includes the mouth, esophagus, stomach, and intestines Gastroscopy- examination of the esophagus, stomach, and the first part of the small intestine (duodenum) using an endoscope inserted through the mouth Gastrostomy- the surgical creation of an opening in the abdominal wall into the stomach for drainage or a feeding tube Gaucher’s disease- a genetic disorder in which lipids cannot be properly broken down and build up in certain cells; causes enlargement of the spleen and liver, bone damage, and anemia Gavage- an artificial feeding technique in which liquids are passed into the stomach by way of a tube inserted through the nose Gene- the basic unit of DNA, which is responsible for passing genetic information; each gene contains the instructions for the production of a certain protein General anesthesia- a method of preventing pain in which the patient is induced to lose consciousness Generic drug- a drug marketed under its chemical name, instead of a brand name Gene therapy- an experimental procedure in which disease-causing genes are replaced by normal, healthy genes Genetic analysis- examination of DNA in a laboratory to diagnose genetic disorders Genetic counseling- information and advice given to persons considering pregnancy about the risk that a child will have an inheritable birth defect or genetic disorder Genetic disorder- a disorder caused partly or completely by a defect in genes, which carry hereditary information Genetic engineering- the alteration of genetic information to change an organism; mainly used to produce vaccines and drugs such as insulin Genital herpes- an infection caused by the herpes simplex virus, which causes a painful rash of fluid-filled blisters on the genitals; transmitted through sexual contact Genital tract- the organs that make up the reproductive system Genital wart- a growth on the skin in or around the vagina, penis, or anus, transmitted by sexual contact; can cause cancer of the cervix Genome- the complete set of an organism’s genes Geographic tongue- a condition in which the tongue is patchy where surface cells break down German measles- the common name for Rubella Germ cell- a sperm or egg cell, or the immature form of either Gestation- the period of time between fertilization of an egg by a sperm and birth of a baby Giardiasis- infection with a single-celled parasite, causing abdominal cramps, diarrhea, and nausea GIFT- see Gamete intrafallopian transfer Gingivectomy- surgical removal of a diseased part of the gums Gingivitis- inflammation of the gums, typically caused by a buildup of plaque due to poor hygiene GI series- see Gastrointestinal series Gland- a group of cells or an organ that produces substances (such as hormones and enzyme) that are used by the body Glaucoma- a disease in which eye damage is caused by an increase in the pressure of the fluid within the eye Glioblastoma multiforme- a fast-growing, cancerous brain tumor Glioma- a brain tumor arising from cells that support nerve cells Glomerulonephritis- inflammation of the filtering structures in the kidneys, hindering removal of waste products from the blood Glomerulosclerosis- scarring of the filtering structures in the kidneys due to damage Glossectomy- surgical removal of all or part of the tongue Glucagon- a hormone produced by the pancreas that converts stored carbohydrates (glycogen) into glucose, the body’s energy source Glucose- a sugar that is the main source of energy for the body Glucose tolerance test- a test that evaluates the body's response to glucose after a period of fasting; used to check for diabetes mellitus Glycogen- the main form that glucose, the body’s energy source, takes when it is stored Glycosuria- glucose in the urine Goiter- enlargement of the thyroid gland, which produces a swelling on the neck Gonadotropic hormones- hormones that stimulate activity in the ovaries and testicles Gonorrhea- a common sexually transmitted disease, characterized by painful urination or a discharge from the penis or vagina Gout- a disorder marked by high levels of uric acid in the blood; usually experienced as arthritis in one joint Graft- healthy tissue that is used to replace diseased or defective tissue Grand mal- a type of seizure occurring with epilepsy, producing loss of consciousness and involuntary jerking movements Granuloma- a mass of tissue that forms at a site of inflammation, injury, or infection as a part of the healing process Graves' disease- an autoimmune disease that causes goiter, overproduction of thyroid hormones, and sometimes bulging eyeballs Guillain-Barré syndrome- a peripheral nervous system disease in which nerve inflammation causes weakness, loss of movement, and loss of sensation in the arms and legs Guthrie test- a blood test performed on babies to test for phenylketonuria  H Hair follicle- a tiny opening in the skin from which a hair grows Halitosis- the clinical term for bad breath; commonly caused by poor oral hygiene or eating certain foods; if persistent it can be a sign of illness Hallucination- a perception that occurs when there is actually nothing there to cause it (such as hearing voices when there are none) Hammer toe- an abnormality in the tendons of the toe that causes the toe to be flexed at all times Hamstring muscle- a muscle located at the back of the thigh that bends the leg at the knee and moves the leg backward Hardening of the arteries- the common name for arteriosclerosis Hashimoto’s disease- a disease in which the body’s immune system attacks cells of the thyroid gland, resulting in a decrease in thyroid hormones Hay fever- the common name for allergic rhinitis HDL- see High-density lipoprotein Heart attack- see Myocardial infarction Heart block- a disorder of the heart caused by a blockage of the nerve impulses to the heart that regulate heartbeat; may lead to dizziness, fainting, or stroke Heartburn- a burning sensation experienced in the center of the chest up to the throat; may be caused by overeating, eating spicy food, or drinking alcohol; recurrent heartburn may be caused by acid reflux Heart disease- see Coronary heart disease Heart failure- the inability of the heart to pump blood effectively Heart-lung machine- a machine that takes over the functions of the heart and lungs during certain types of surgery Heart rate- the rate at which the heart pumps blood, measured in the number of heartbeats per minute Heart valve- the structure at each exit of the four chambers of the heart that allows blood to exit but not to flow back in Heat exhaustion- fatigue, dizziness, and nausea experienced because of overexposure to heat; if not treated it can result in heat stroke Heat stroke- a life-threatening condition resulting from extreme overexposure to heat, which disrupts the body's system of regulating temperature Heel spur- an abnormal, often painful outgrowth of bone on the back of the heel Heimlich maneuver- a first-aid technique for choking; dislodges an object that is blocking a person’s airway Helper T cells- white blood cells, responsible for regulating other cells in the body's immune system, that are the main targets of the AIDS virus; also called CD4 cells Hemangioma- a purple-red mark on the skin, caused by an excess of blood vessels Hemarthrosis- bleeding into and swelling of a joint Hematemesis- vomiting of blood Hematocrit- the percentage of total blood volume that consists of red blood cells, which is determined by laboratory testing; can be an indicator of disease or injury Hematoma- an accumulation of blood from a broken blood vessel Hematuria- blood in the urine, which can be caused by urinary tract disorders (such as cysts, tumor, or stones) or by an infection Hemochromatosis- a genetic disorder in which too much iron is absorbed from food Hemodialysis- a method used to treat kidney failure, in which blood is passed through a machine that purifies it and returns it to the body Hemoglobin- the pigment in red blood cells that is responsible for carrying oxygen; hemoglobin bound to oxygen gives blood its red color Hemoglobinuria- hemoglobin in the urine Hemolysis- the breakdown of red blood cells in the spleen, which is normal but can cause jaundice and anemia when the red blood cells are broken down too quickly Hemophilia- an inherited disorder in which a person's blood lacks a certain protein important in forming blood clots, leading to excessive bleeding Hemorrhage- the medical term for bleeding Hemorrhoid- a bulging vein either at the opening of the anus or just inside the anus, often caused by childbirth or straining during bowel movements Hemospermia- blood in the semen Hemostasis- the stopping of bleeding by the body’s mechanisms Hemothorax- an accumulation of blood between the chest wall and the lungs Hepatectomy- surgical removal of all or part of the liver Hepatic- a term used to describe something that is related to the liver Hepatitis- inflammation of the liver, which may be caused by a viral infection, poisons, or the use of alcohol or other drugs Hepatitis A- a form of hepatitis caused by the hepatitis A virus, usually transmitted by contact with contaminated food or water Hepatitis B- a form of hepatitis (generally more serious than hepatitis A) caused by the hepatitis B virus, which is transmitted through sexual contact or contact with infected blood or body fluids Hepatitis C- a form of hepatitis caused by the hepatitis C virus, which is transmitted through sexual contact or contact with infected blood or body fluids Hepatitis D- a form of hepatitis that only causes symptoms when the individual is already infected with hepatitis B Hepatoma- a cancerous tumor of the liver Hepatomegaly- enlargement of the liver Hereditary- describes a genetic trait that is passed from parents to children Hereditary spherocytosis- a genetic disorder in which red blood cells are smaller, rounder, and more fragile than normal, causing hemolytic anemia Hermaphroditism- a rare condition in which an individual is born with both male and female reproductive organs Hernia- the bulging of an organ or tissue through a weakened area in the muscle wall Herniated disk- see Disk prolapse Herpes encephalitis- brain inflammation caused by a herpes simplex virus that has spread from another part of the body Herpes simplex- infection by the herpes simplex virus, which causes blisterlike sores on the face, lips, mouth, or genitals; in rare cases, can also affect the eyes, fingers, or brain Herpes zoster- see Shingles Heterosexuality- being sexually attracted to members of the opposite sex Hiatal hernia- a type of hernia in which the stomach bulges up into the chest cavity through an opening in the diaphragm Hiccup- involuntary sudden contraction of the diaphragm along with the closing of the vocal cords, producing a "hiccup" sound High-density lipoprotein- a type of protein found in the blood that removes cholesterol from tissues, protecting against heart disease Hirschsprung's disease- a condition that is present at birth in which nerve cells do not develop in parts of the intestine, causing the intestine to narrow and block the passage of feces Hirsutism- excessive hair or hair growth in unusual places, especially in women Histamine- a chemical in some cells of the body that is released during allergic reactions, causing inflammation; also causes production of acid in the stomach and narrowing of the airways H1 (histamine) blocker- a drug that blocks the action of histamine; used to treat inflammation H2 (histamine) blocker- a drug used in the treatment of peptic ulcers that blocks histamine from causing acid production in the stomach Histoplasmosis- a respiratory disease acquired by inhaling the spores of a fungus found in soil, especially where there are bird or bat droppings HIV- see Human immunodeficiency virus Hives- the common term for urticaria, an itchy, inflamed rash that results from an allergic reaction Hodgkin's disease- a cancer of lymphoid tissue (found in lymph nodes and the spleen) that causes the lymph nodes to enlarge and function improperly; may cause illness, fever, loss of appetite, and weight loss Homeostasis- the body's coordinated maintenance of the stable, internal environment by regulating blood pressure, blood sugar, body temperature, etc Homocystinuria- a genetic disorder in which an enzyme deficiency causes a substance called homocystine to build up in the blood, leading to mental handicap and skeletal abnormalities Homosexuality- being sexually attracted to members of the same sex Hookworm- infestation by a small, round, blood-sucking parasite; commonly causes a rash on the foot, but can also cause cough, pneumonia, and anemia Hormonal implant- surgical insertion of a small object just under the skin that slowly releases a synthetic hormone for purposes such as birth control Hormone- a chemical produced by a gland or tissue that is released into the bloodstream; controls body functions such as growth and sexual development Hormone replacement therapy- the use of natural or artificial hormones to treat hormone deficiencies Hospice- a hospital or an area of a hospital dedicated to treating people who are dying, often of a specific cause Hot flash- a sudden, temporary feeling of heat and sometimes sweating; usually occurs as a result of low estrogen levels in women because of menopause or after a hysterectomy HTLV- see Human T-cell lymphotrophic virus Human immunodeficiency virus- a retrovirus that attacks helper T cells of the immune system and causes acquired immunodeficiency syndrome (AIDS); transmitted through sexual intercourse or contact with infected blood Human T-cell lymphotrophic virus- a virus similar to HIV that affects the same helper T cells, but usually accompanies adult T-cell leukemia or T-cell lymphomas Hydramnios- an excess of amniotic fluid in the uterus during pregnancy Hydrocele- a painless swelling of the scrotum, caused by a collection of fluid around the testicle; commonly occurs in middle aged men Hydrocephalus- excess cerebrospinal fluid within the brain; commonly referred to as "water on the brain" Hydrocortisone- a corticosteroid drug that is used to treat inflammation and allergies Hygiene- the practice, maintenance, and study of health; commonly refers to cleanliness Hymen- a thin fold of membrane partly closing the opening of the vagina; usually torn during first sexual intercourse or insertion of a tampon Hyperactivity- a type of behavior characterized by excessive physical activity, sometimes associated with neurological or psychological causes Hyperalimentation- a method of providing nutrients by the use of a tube or intravenously to a person who cannot eat food or needs nutrients because of an illness Hyperbilirubinemia- a condition in which there is too much bilirubin, a substance produced when red blood cells are broken down; can lead to jaundice Hypercalcemia- a condition marked by abnormally high levels of calcium in the blood; can lead to disturbance of cell function in the nerves and muscles and, if not treated, can be fatal Hypercholesterolemia- an abnormally high level of cholesterol in the blood, which can be the result of an inherited disorder or a diet that is high in fat Hyperglycemia- a condition characterized by abnormally high levels of glucose in the blood, usually as a result of untreated or improperly controlled diabetes mellitus Hyperlipidemia- a general term for a group of disorders in which lipid levels in the blood are abnormally high, including hypercholesterolemia Hyperparathyroidism- overactivity of the parathyroid glands, which increases calcium levels in the blood (called hypercalcemia) and decreases calcium in bones (causing osteoporosis) Hyperplasia- the enlargement of an organ or tissue Hypersensitivity- an excessive response of the body’s immune system to a foreign protein Hypertension- abnormally high blood pressure, even when at rest Hyperthermia- an abnormally high body temperature Hyperthyroidism- overactivity of the thyroid gland, causing nervousness, weight loss, fatigue, and diarrhea Hypertrophy- increase in the size of an organ due to an increase in the size of its cells Hyperventilation- abnormally rapid breathing Hypochondriasis- an abnormal condition in which a person is overly concerned with health and believes that he or she is suffering from a major illness despite medical opinion to the contrary Hypodermic needle- a thin, hollow needle attached to a syringe; used to inject a medication under the skin, into a vein, or into a muscle Hypoglycemia- abnormally low levels of glucose in the blood Hypoplasia- failure of a tissue or organ to develop normally Hypotension- the medical term for abnormally low blood pressure, which results in reduced blood flow to the brain, causing dizziness and fainting Hypothermia- an abnormally low body temperature Hypothyroidism- underactivity of the thyroid gland, causing tiredness, cramps, a slowed heart rate, and possibly weight gain Hypoventilation- a slower-than-normal breathing rate Hypoxemia- a reduced level of oxygen in the blood Hypoxia- a reduced level of oxygen in tissues Hysterectomy- surgical removal of the uterus Hysteria- a term used to describe symptoms that are caused by mental stress and occur in someone who does not have a mental disorder Hysterosalpingography- an X-ray examination performed to examine the inside of the uterus and fallopian tubes, in order to investigate and possibly treat infertility Hysteroscopy- a method used to examine the inside of the uterus and the cervix using a viewing instrument  I Iatrogenic- a term used to describe a disease, disorder, or medical condition that is a direct result of medical treatment Ichthyosis- a variety of diseases in which the skin is dry and scaly Idiopathic- a term used to describe something that occurs of an unknown cause Ileostomy- a surgical procedure in which the lower part of the small intestine (the ileum) is cut and brought to an opening in the abdominal wall, where feces can be passed out of the body Ileum- the lowest section of the small intestine, which attaches to the large intestine Ilium- one of the two bones that form the hip on either side of the body Imaging- the technique of creating pictures of structures inside of the body using X-rays, ultrasound waves, or magnetic fields Immune deficiency- impairment of the immune system, which reduces protection against infection and illness Immune system- the cells, substances, and structures in the body that protect against infection and illness Immunity- resistance to a specific disease because of the responses of the immune system Immunization- the process of causing immunity by injecting antibodies or provoking the body to make its own antibodies against a certain microorganism Immunocompromised- weakening of the body’s immune system Immunodeficiency- failure of the body’s immune system to fight disease Immunoglobin- proteins in blood and tissue fluids that help destroy microorganisms such as bacteria and viruses Immunology- the study of the immune system, including how it functions and disorders that affect it Immunostimulant- a drug that increases the ability of the body’s immune system to fight disease Immunosuppressant- a drug that inhibits the activity of the immune system; used to prevent rejection of a transplant organ and in disorders where the body's immune system attacks its own tissues Impacted fracture- a bone break in which the two broken ends have been forced into each other Imperforate anus- a birth defect in which the opening of the anus is not formed normally Impetigo- a highly contagious skin infection caused by bacteria, usually occurring around the nose and mouth; commonly occurring in children Implant- an organ, tissue, or device surgically inserted and left in the body Impotence- the inability to acquire or maintain an erection of the penis Incompetent cervix- an abnormally weak cervix, which widens prematurely during pregnancy as a result of the weight of a developing fetus; may result in a miscarriage Incontinence- inability to hold urine or feces inside of the body Incubation period- the time period between when an infectious organism enters the body and when symptoms occur Indigestion- uncomfortable symptoms brought on by overeating or eating spicy, rich, or fatty foods; characterized by heartburn, pain in the abdomen, nausea, and gas, and can be more serious if recurrent Induction of labor- the use of artificial means to start the process of childbirth Infarction- tissue death due to lack of blood supply Infection- disease-causing microorganisms that enter the body, multiply, and damage cells or release toxins Infective arthritis- arthritis caused by bacteria from a wound or the bloodstream entering a joint Infertility- the inability to have children as a result of sexual intercourse Inflammation- redness, pain, and swelling in an injured or infected tissue produced as a result of the body's healing response Inflammatory bowel disease- the general term for two inflammatory disorders affecting the intestines; also known as Crohn's disease and ulcerative colitis Inflammatory joint disease- any type of arthritis that causes a joint to become inflamed Influenza- a viral infection characterized by headaches, muscle aches, fever, weakness, and cough; commonly called the "flu" Informed consent- agreement to undergo a medical procedure after the technique, its risks, and its possible complications have been explained Infusion- the introduction of a substance, such as a drug or nutrient, into the bloodstream or a body cavity Ingestion- taking something into the body through the mouth Ingrown toenail- a painful condition of the big toe in which the nail grows into the skin on either side, causing inflammation and/or infection Inguinal hernia- the bulging of a portion of the intestines or abdominal tissue into the muscles of the groin (the area just below the abdomen) Inhaler- a device used to introduce a powdered or misted drug into the lungs through the mouth, usually to treat respiratory disorders such as asthma Inheritance- the passing of traits from parent to child through genes Injection- the use of a syringe and needle to insert a drug into a vein, muscle, or joint or under the skin Insemination- the placement of semen into a woman's uterus, cervix, or vagina In situ- "in place"; often describes a cancer that has not spread Insomnia- difficulty falling or remaining asleep Insulin- a hormone made in the pancreas that plays an important role in the absorption of glucose (the body's main source of energy) into muscle cells Insulinoma- a noncancerous tumor of the insulin-producing cells of the pancreas; the tumor releases excess insulin into the blood, causing glucose levels to drop dangerously low Intensive care- close monitoring of a patient who is seriously ill Interferon- a protein produced by body cells that fights viral infections and certain cancers Internal fixation- a method of holding a broken bone in place using surgically inserted screws, rods, or plates Interstitial- lying between body structures or in the interspaces of tissues Interstitial cystitis- persistent inflammation of the lining and muscle of the bladder Interstitial lung disease- a disease of the connective tissue surrounding the air sacs of the lungs that causes a dry cough, scarring of lung tissue, and shortness of breath Interstitial pulmonary fibrosis- scarring of connective tissue in the lungs that leads to shortness of breath Interstitial radiation therapy- a treatment for cancer in which a radioactive material is inserted into or near a tumor to provide direct radiation Intervertebral disks- broad, flat cartilage structures containing a gel-like fluid that cushion and separate vertebrae Intestinal bypass- a surgical procedure in which the beginning of the large intestine is joined to its end so that less food is absorbed; because of serious side effects, usually performed only on seriously obese people Intestine- a long, tube-shaped organ that extends from the stomach to the anus; absorbs food and water and passes the waste products of digestion as feces Intra-aortic balloon pump- a small balloon inserted into the aorta that helps to circulate blood by inflating between heartbeats Intractable- describes a condition that does not respond to treatment Intramedullary rod- a strong metal rod that is placed inside of a broken bone to help it heal correctly Intraocular pressure- the pressure of the fluids within the eye Intrauterine device- a device inserted into the uterus that helps to prevent pregnancy Intravenous- inside of or into a vein Intrinsic- a term used to describe something originating from or located in a tissue or organ Intubation- the passage of a tube into an organ or body structure; commonly used to refer to the passage of a tube down the windpipe for artificial respiration Invasive- describes something that spreads throughout body tissues, such as a tumor or microorganism; also describes a medical procedure in which body tissues are penetrated In vitro- "in glass"; a biological test or process that is carried out in a laboratory In vitro fertilization- a treatment for infertility in which an egg and a sperm are joined outside the woman's body, and the fertilized egg is then inserted into the uterus or fallopian tube In vivo- "in the living body"; a biological process that occurs inside of the body Involuntary- occurring without a person’s control or participation Iodine- an element for the formation of thyroid hormones Ionizing radiation- radiation that damages cells or genes; can be used to treat cancer IQ- intelligence quotient; a measure of a person's intelligence as determined by specific tests Iris- the colored part of the eye Iron- a mineral necessary for the formation of important biological substances such as hemoglobin, myoglobin, and certain enzymes Iron-deficiency anemia- a type of anemia caused by a greater-than-normal loss of iron due to bleeding, problems absorbing iron, or a lack of iron in the diet Irrigation- the cleansing of a wound by flushing it with water, a medicated solution, or some other fluid Irritable bladder- involuntary contractions of muscles in the bladder, which can cause lack of control of urination Irritable bowel syndrome- abnormal muscle movement in the intestines, which causes abdominal pain and irregular bowel movements (diarrhea, constipation, or both) Ischemia- a condition in which a tissue or organ does not receive a sufficient supply of blood IUD- see Intrauterine device IVF- see In vitro fertilization  J Jaundice- yellowing of the skin and whites of the eyes because of the presence of excess bilirubin in the blood; usually a sign of a disorder of the liver Jock itch- an infection in the groin area caused by a fungus Juvenile rheumatoid arthritis- a rare form of persistent joint inflammation that affects children  K Kaposi's sarcoma- a skin cancer that is characterized by purple-red tumors that start at the feet and spread upward on the body; commonly occurs in people who have AIDS Kawasaki disease- a childhood disease causing fever, rash, skin peeling, swollen lymph nodes, and possibly complications of the heart and brain Keloid- a raised, firm, thick scar that forms as a result of a defect in the natural healing process Keratin- a tough protein found in skin, nails, and hair Keratitis- inflammation of the cornea Keratolytic- drugs that remove the keratin-containing outer layer of skin; used to treat skin disorders such as warts and dandruff Keratoplasty- surgical replacement or reshaping of the cornea Keratosis- a growth on the skin that is the result of overproduction of the protein keratin Ketoacidosis- the dangerous accumulation of chemicals called ketones in the blood, sometimes occurring as a complication of diabetes mellitus; also called ketosis Kidney- one of two organs that are part of the urinary tract; responsible for filtering the blood and removing waste products and excess water as urine Kidney stone- a hard mass composed of substances from the urine that form in the kidneys Killer T cells- white blood cells that are part of the immune system and destroy microorganisms and cancer cells Kilocalorie- a unit of energy; equal to a nutritional calorie Kimmelstiel-Wilson syndrome- a kidney disorder that can occur as a complication of diabetes mellitus; can cause swelling, high blood pressure, and kidney failure Klinefelter’s syndrome- a genetic disorder in which a man has at least 1 extra X chromosome in his cells, causing infertility and female characteristics Knee-jerk reflex- a test for a reflexive extension of the leg to check the functioning of the nervous system; tapping the knee just below the kneecap should cause the lower part of the leg to jerk upward Kyphosis- excessive curvature of the spine, which usually affects the top part of the spine and causes a hump  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  M Macula- the area of the retina that allows fine details to be observed at the center of vision; also refers to any small, flat spot on the skin Macular degeneration- gradual loss of vision due to deterioration of nerve tissue in the retina Magnesium- a mineral that is essential for many body functions, including nerve impulse transmission, formation of bones and teeth, and muscle contraction Magnetic resonance imaging (MRI)- a technique that uses magnetic fields and radio waves to create high-quality cross-sectional images of the body without using radiation Malabsorption- an impaired ability of the lining of the small intestine to absorb nutrients from food Malaria- a parasitic disease spread by mosquitos that causes chills and fever; potentially fatal complications in the liver, kidneys, blood, and brain are possible Malformation- abnormal development of an organ or tissue Malignant- a word used to describe a condition that is characterized by uncontrolled growth and/or that can be fatal, such as a cancerous tumor Malignant hyperthermia- a reaction to certain anesthesia gases involving intense muscle contractions and a high fever Malignant melanoma- the most serious type of skin cancer, in which a mole changes shape, darkens, becomes painful, and/or bleeds easily Mallory-Weiss syndrome- a condition associated with alcoholism in which the lower end of the esophagus tears, causing vomiting of blood Mammography- an X-ray procedure done to detect breast cancer Mammoplasty- a general term for a cosmetic operation on the breasts; includes breast reduction, enlargement, and reconstruction after a mastectomy Mandible- another term for the lower jaw Mania- a mental disorder characterized by extreme excitement, happiness, overactivity, and agitation; usually refers to the high of the highs and lows experienced in manic- depressive disorder Manic-depressive disorder- a mental disorder characterized by extreme mood swings, including either mania, depression, or a continuing shift between the two extremes MAO inhibitor- see Monoamine oxidase inhibitor antidepressant Marfan's syndrome- a rare genetic disorder that affects connective tissue, leading to abnormalities of joints, bones, tendons, ligaments, arteries, and/or the heart Mast cell- a type of cell present in most body tissues that releases substances in response to an allergen, which causes symptoms such as inflammation Mastectomy- a surgical procedure in which all or part of the breast is removed to prevent the spread of cancer Mastitis- inflammation of the breast, which is usually caused by a bacterial infection Maxilla- one of two bones that form the upper jaw, the roof of the mouth, and the center portion of the face Measles- an illness caused by a viral infection, causing a characteristic rash and a fever; primarily affects children Meconium- thick, sticky, greenish-brown stool passed by a postmature fetus, or one experiencing fetal distress,