abdomen - area between the chest and the hips that contains the stomach, small intestine, large intestine, liver, gallbladder, pancreas, and spleen.

abdominal bracing - technique of tensing the stomach muscles to support the spine.

abdominal hysterectomy - a procedure in which the uterus is removed through the abdomen via a surgical incision.

abdominoplasty (Also called "tummy tuck.") - a procedure that minimizes the abdominal area. In abdominoplasty, the surgeon makes a long incision from one side of the hipbone to the other. Excess fat and skin are surgically removed from the middle and lower abdomen and the muscles of the abdomen wall are tightened.

abdominoscopy - a type of surgery using a laparoscope (a long, thin tube with a camera lens attached), which is inserted into one or more small incisions, to examine the abdominal cavity.

ablation - elimination or removal.

ablative therapy - treatment that removes or destroys the function of an organ, such as surgical removal of an organ or some types of chemotherapy.

abortion - medical termination of a pregnancy before the fetus has developed enough to survive outside the uterus.

abscess - a hole filled with pus that forms as a result of a local infection.

absorption - the process by which nutrients from food move from the small intestine into the cells in the body.

abutment teeth - the surrounding teeth of each side of the gap where teeth are missing.

accessory digestive organs - organs that help with digestion but are not part of the digestive tract. These organs include the tongue, pancreas, liver, gallbladder, and glands in the mouth that make saliva.

accessory movement - joint movements that cannot be performed voluntarily or in isolation by the patient.

accommodation - the ability of the eye to focus.

ACE (angiotensin-converting enzyme) inhibitor - a medication that lowers blood pressure.

acetaminophen - a pain-relieving and fever-reducing drug found in many over-the-counter medications (i.e., Tylenol, Tempra, or Feverall).

acetylcholine - a chemical in the brain that acts as a neurotransmitter.

achalasia - a rare disorder of the esophagus in which the muscle at the end of the esophagus does not relax enough for the passage to open properly.

Achilles tendonitis - Inflammation of the Achilles tendon.

acne - a chronic disorder of the hair follicles and sebaceous glands. Acne is characterized by black heads, pimple outbreaks, cysts, infected abscesses, and (sometimes) scarring.

acoustic neurinoma - a tumor, usually benign, which develops on the hearing and balance nerves and can cause gradual hearing loss, tinnitus, and dizziness.

acquired deafness - loss of hearing that occurs or develops over the course of a lifetime; deafness not present at birth.

acquired immune deficiency syndrome (AIDS) - a disease caused by the human immunodeficiency virus (HIV), which kills or impairs cells of the immune system and progressively destroys the body's ability to fight infections and certain cancers. HIV is most commonly spread by sexual contact with an infected partner. The term AIDS applies to the most advanced stages of an HIV infection.

acromegaly - excessive growth due to the production of excessive growth
hormone by the pituitary gland.

acromion - the roof, or highest point, of the shoulder that is formed by a part of the scapula, or shoulder blade.

actinic keratosis - a precancerous condition of thick, scaly patches of skin.

action tremor - a tremor that increases when the hand is moving voluntarily.

activated charcoal - an over-the-counter product that may help relieve intestinal gas.

activities of daily living (ADLs) - personal care activities necessary for everyday living, such as eating, bathing, grooming, dressing, and toileting; a term often used by healthcare professionals to assess the need and/or type of care a person may require.

acupuncture points - anatomic points on the body used in acupuncture.

acute - severe; sharp; begins quickly.

acute appendicitis - acute inflammation of the appendix due to infection.

acute lymphocytic leukemia (ALL) - a rapidly progressing cancer of the blood in which too many immature (not fully formed) lymphocytes, a type of white blood cell, are found in the bone marrow, blood, spleen, liver, and other organs.

acute myelogenous leukemia (AML) - a rapidly progressing cancer of the blood in which too many immature (not fully formed) granulocytes, a type of white blood cell, are found in the bone marrow and blood.

adenocarcinoma - cancerous tumors of the glands, such as in the ducts or lobules of the breast.

adenoma - benign growths which often appear on glands or in glandular tissue.

adhesion - a band of scar tissue that joins normally separated internal body structures, most often after surgery, inflammation, or injury in the area.

adhesions - abnormal bands of tissue that grow between joint surfaces, restricting motion.

adjuvant treatment - treatment that is added to other therapies to increase effectiveness.

adrenal cortex - outer portion of the adrenal gland that secretes hormones that are vital to the body.

adrenal glands - two small glands located on top of the kidneys that secrete hormones.

adrenaline (Also called epinephrine.) - one of two chemicals (the other is norepinephrine) released by the adrenal gland that increases the speed and force of heart beats. It dilates the airways to improve breathing and narrows blood vessels in the skin and intestine so that an increased flow of blood reaches the muscles and allows them to cope with the demands of exercise.

advance directives - legal documents, such as living wills and durable powers of attorney for healthcare decisions, stating a patient's medical preferences in the event the patient should become incapable of voicing his/her opinion.

advanced cancer - stage of cancer in which the disease has spread from the primary site to other parts of the body.

aerophagia - condition that occurs when a person swallows too much air; causes gas and frequent belching.

African trypanosomiasis (Also called "African sleeping sickness.") - a systemic disease caused by parasite of the Trypanosoma brucei family, and transmitted by the bite of the tsetse fly. There is West African trypanosomiasis and East African trypanosomiasis, referring to the areas in Africa where they are found.

ageusia - loss of the sense of taste.

agitation - a non-specific symptom of one or more physical or psychological processes in which vocal or motor behavior (screaming, shouting, complaining, moaning, cursing, pacing, fidgeting, wandering) pose risk or discomfort, become disruptive or unsafe, or interfere with the delivery of care in a particular environment.

agonist - a drug that increases neurotransmitter activity by stimulating the dopamine receptors directly.

agoraphobia - a Greek word that literally means "fear of the marketplace." This anxiety disorder involves the fear of experiencing a panic attack in a place or situation from which escape may be difficult or embarrassing.

air bags - safety devices installed in most newer vehicles that inflate to protect the driver and/or passenger in certain collisions.

air pollution - the presence of noxious substances in the air that we breathe.

akinesia - no movement.

alactasia - inherited condition that causes a lack of the enzyme needed to digest milk sugar.

albinism - a rare, inherited disorder characterized by a total or partial lack of melanin (skin pigment) in the skin.

albumin - a protein found in blood plasma and urine, which can be a sign of kidney disease.

alcohol-induced chronic hepatitis - one type of hepatitis; continued liver damage throughout the liver from heavy alcohol consumption.

aldosterone - a hormone secreted by the adrenal cortex that controls sodium and potassium in the blood.

alimentary canal - gastrointestinal (GI) tract.

allergen - a substance that triggers an allergic reaction.

allergic conjunctivitis - red, itchy, watery eyes; a result of an exposure to an allergen or an irritant.

allergy - an acquired, abnormal immune response to a substance that can cause a broad range of inflammatory reactions.

allodynia - pain due to a stimulus that does not normally provoke pain.

allogeneic bone marrow transplantation - a procedure in which a person receives stem cells from a compatible donor.

allogeneic transplant - the transfer of bone marrow from one person to another.

alopecia - a partial or complete loss of hair that may result from radiation therapy to the head, chemotherapy, skin disease, drug therapy, and natural causes.

alpha thalassemia - an inherited blood disorder affecting the alpha chains of the hemoglobin molecule.

alpha-fetoprotein (AFP) - a protein produced by a developing fetus that is present in amniotic fluid and, in smaller amounts, in a pregnant woman's blood. Abnormal levels of AFP found in a blood test between the 15th and 18th weeks of pregnancy can indicate abnormalities in the fetus.

Alport's syndrome - A hereditary condition characterized by kidney disease, sensorineural hearing loss, and some difficulties with eye defects.

alternative medicine - any form of therapy used alone, without recommended standard/conventional treatment.

alveolus - air sac where gas exchange takes place.

Alzheimer's disease - A progressive, degenerative disease that occurs in the brain and results in impaired memory, thinking, and behavior.

amblyopia - sometimes called "lazy eye," is the reduction or dimming of vision in an eye that appears to be normal.

amebiasis - acute or chronic infection; symptoms vary from mild diarrhea to frequent, watery diarrhea and loss of water and fluids in the body.

amenorrhea - absence or cessation of menstrual periods.

amenorrhea, primary - from the beginning and lifelong; menstruation never begins at puberty.

amenorrhea, secondary - due to some physical cause and usually of later onset; a condition in which menstrual periods which were at one time normal and regular become increasing abnormal and irregular or absent.

American Cancer Society (ACS) - An organization that supports research, produces educational materials and programs, and offers many other services to cancer patients and their families.

American National Standards Institute (ANSI) - An organization that evaluates and approves helmets.

American Sign Language (ASL) - Manual (hand) language with its own syntax and grammar used primarily by people who are deaf.

American Society for Testing and Materials (ASTM) - An organization that evaluates and approves helmets.

amniocentesis - a test performed to determine chromosomal and genetic disorders and certain birth defects. The test involves inserting a needle through the abdominal and uterine wall into the amniotic sac to retrieve a sample of amniotic fluid.

amniotic fluid - clear liquid that surrounds and protects the fetus throughout pregnancy.

amniotic sac - a thin-walled sac that surrounds the fetus during pregnancy. The sac is filled with amniotic fluid - liquid made by the fetus and the amnion (the membrane that covers the fetal side of the placenta) which protects the fetus from injury and helps to regulate the temperature of the fetus.

Amsler grid - A chart featuring horizontal and vertical lines used to test vision.

amyloidosis - a rare disease which causes the build-up of amyloid, a protein
and starch, in tissues and organs.

amyotrophic lateral sclerosis (Also called ALS or Lou Gehrig's disease.) - a terminal, neurological disorder characterized by progressive degeneration of motor cells in the spinal cord and brain.

anal fissure - small tear in the anus that may cause itching, pain, or bleeding.

anal fistula - channel that develops between the anus and the skin. Most fistulas are the result of an abscess (infection) that spreads to the skin.

analgesia - absence of pain in response to stimulation that would normally be painful.

analgesic - any drug intended to alleviate pain.

anaphylaxis (Also called anaphylactic shock.) - a sudden, severe, potentially life-threatening allergic reaction caused by food allergy, insect stings, or medications. Symptoms can include hives, swelling (especially of the lips and face), difficulty breathing (either because of swelling in the throat or an asthmatic reaction), vomiting, diarrhea, cramping, and a fall in blood pressure.

anastomosis - operation to connect two body parts. An example is an operation in which a part of the colon is removed and the two remaining ends are rejoined.

androgen hormone - a hormone that stimulates activity of male sex organs, and encourages development of male sex characteristics.

anemia - blood disorder caused by a deficiency of red blood cells or hemoglobin (the oxygen-carrying protein in red blood cells).

anesthesia - lack of normal sensation, especially the awareness of pain, which may be brought on by anesthetic drugs. General anesthesia causes loss of consciousness; local or regional anesthesia causes loss of feeling only to a specified area.

anesthetics - medications that cause loss of sensation to pain or awareness.

aneurysm - a weakened, pouched area on the wall of an artery.

angina pectoris (Also called angina.) - recurring chest pain or discomfort that happens when some part of the heart does not receive enough blood.

angiodysplasia - abnormal or enlarged blood vessels in the gastrointestinal tract.

angiogenesis - the formation of new blood vessels.

angiogenesis inhibitor - a chemical which signals the process of angiogenesis to stop.

angiography - an x-ray that uses dye injected into arteries so that blood circulation can be studied.

angioma - a benign tumor in the skin, which is made up of blood or lymph vessels.

angioplasty - the use of a small balloon on the tip of a catheter inserted into a blood vessel to open up an area of blockage inside the vessel.

ankle sprain - over-stretched lateral (outside) ligament of the ankle joint.

ankylosing spondylitis - a disease that affects the spine, causing the bones of the spine to grow together.

anomaly - a health problem or feature not normally present in a healthy individual; a deviation from the normal.

anorexia nervosa (Also called anorexia.) - an eating disorder characterized by low body weight (less than 85 percent of normal weight for height and age), a distorted body image, and an intense fear of gaining weight.

anoscopy - test to look for fissures, fistulae, and hemorrhoids using a special instrument, called an anoscope, to look into the anus.

anosmia - absence of the sense of smell.

anovulation - failure of the ovaries to produce or release mature eggs.

antacids - medications that balance acids and gas in the stomach.

anterior chamber - the front section of the eye's interior where aqueous humor flows in and out of providing nourishment to the eye and surrounding tissues.

anterior cruciate ligament (ACL) - the ligament, located in the center of the knee, that controls rotation and forward movement of the tibia (shin bone).

anterolateral shin splint - a type of shin splint that affects the front and outer part of the muscles of the shin and is caused by a congenital (present at birth) imbalance in the size of opposite muscles.

antibiotic - a chemical substance produced by living organisms or synthesized (created) in laboratories for the purpose of killing other organisms that cause disease.

antibodies - proteins produced by the immune system to fight specific bacteria, viruses, or other antigens.

antibody - a special protein produced by the body’s immune system that recognizes and helps fight infectious agents and other foreign substances that invade the body.

anticholinergics - medications that calm muscle spasms in the intestine.

anticipatory grief - the deep emotional distress that occurs when someone has a prolonged illness and death is expected often by the patient as well as the family. Anticipatory grief can be just as painful and stressful as the actual death of the person.

anticoagulant - a medication that keeps blood from clotting.

antidiarrheals - medications that help control diarrhea.

antiemetics - medications that prevent and control nausea and vomiting.

antiestrogen - substance (i.e., tamoxifen) that blocks the effects of estrogen on tumors.

antigen - a substance that can trigger an immune response causing the production of antibodies as part of the body's defense against infection and disease.

antihistamine - a medication that blocks the effects of histamine, a chemical released in body fluids during an allergic reaction.

antihypertensive - a medication or other therapy that lowers blood pressure.

anti-inflammatory - medications that reduce the symptoms and signs of inflammation.

antioxidants - compounds that protect against cell damage inflicted by molecules, called oxygen-free radicals, which are a major cause of disease and aging.

antisocial personality disorder - persons with this disorder characteristically disregard the feelings, property, authority, and respect of others for their own personal gain. This may include violent or aggressive acts involving or targeting other individuals, without a sense or remorse or guilt for any of their destructive actions.

antispasmodics - medications that help reduce or stop muscle spasms in the intestines.

antivenin - an antidote to snake venom used to treat serious snake bites. Antivenin is derived from antibodies created in a horse’s blood serum when the animal is injected with snake venom. Because antivenin is obtained from horses, snake bite victims sensitive to horse products must be carefully managed.

antrectomy - operation to remove the upper portion of the stomach, called the antrum, to help reduce the amount of stomach acid.

anus - opening at the end of the digestive tract where the bowel contents leave the body.

aorta - blood vessel that delivers oxygen-rich blood from the left ventricle to the body; it is the largest blood vessel in the body.

aortic valve - the valve that regulates blood flow from the heart into the aorta.

Apert syndrome - A craniofacial abnormality characterized by an abnormal head shape, small upper jaw, and fusion of the fingers and toes.

apex - top portion of the upper lobes of the lungs.

Apgar test - A scoring system to evaluate the condition of a newborn immediately after birth.

aphasia - total or partial loss of ability to use or understand language; usually caused by stroke, brain disease, or injury.

apheresis - a procedure in which blood is removed from a patient, certain fluid and cellular elements are removed, and the blood is then infused back into the patient.

aphonia - complete loss of voice.

aplastic anemia - one type of anemia that occurs when the bone marrow produces too few of all three types of blood cells: red blood cells, white blood cells, and platelets.

appendectomy - the surgical removal of the appendix (to treat acute appendicitis.)

appendicitis - inflammation and reddening of the appendix caused by infection, scarring, or blockage.

appendix - a small pouch, attached to the first part of the large intestine, whose function in the body is unknown.

apraxia - inability to make a voluntary movement in spite of being able to demonstrate normal muscle function.

areola - dark area of skin that surrounds the nipple of the breast.

arrhythmia (Also called dysrhythmia.) - an abnormal heartbeat.

arteriogram (Also called an angiogram.) - an x-ray of the arteries to detect blockage or narrowing of the vessels.

arterioles - small branches of arteries.

arteriosclerosis (Also called "hardening of the arteries.") - a variety of conditions caused by fatty or calcium deposits in the artery walls causing them to thicken.

artery - a blood vessel that carries oxygenated blood away from the heart to the body.

arthralgia - pain in a joint, usually due to arthritis or arthropathy.

arthritis - inflammation of a joint, usually accompanied by pain, swelling, and sometimes a change in structure.

arthrogram - an x-ray to view bone structures following an injection of a contrast fluid into a joint area. When the fluid leaks into an area that it does not belong, disease or injury may be considered, as a leak would provide evidence of a tear, opening, or blockage.

arthroplasty - total joint replacement.

arthroscopy - a minimally-invasive diagnostic and treatment procedure used for conditions of a joint. This procedure uses a small, lighted, optic tube (arthroscope) which is inserted into the joint through a small incision in the joint. Images of the inside of the joint are projected onto a screen; used to evaluate any degenerative and/or arthritic changes in the joint; to detect bone diseases and tumors; to determine the cause of bone pain and inflammation.

articular cartilage - covers the ends of bones and allows the distribution of compressive loads over the cross section of bones; provides frictionless and wear-resistant surface for joint movement.

articulation disorder - inability to correctly produce speech sounds (phonemes) because of imprecise placement, timing, pressure, speed, or flow of movement of the lips, tongue, or throat.

artificial insemination - a procedure that involves the placement of relatively large numbers of healthy sperm either at the entrance of the cervix or into a women's uterus, bypassing the cervix, to have direct access to the fallopian tubes.

artificial ventilation - the process of supporting breathing by manual or mechanical means when normal breathing is inefficient or has stopped.

ascending colon - part of the colon on the right side of the abdomen.

ascites - fluid build-up in the abdominal cavity.

assisted living facility (ALF) - an out-of-home care option for elderly persons who continue to lead relatively active, healthy, and independent lives. Most ALFs feature apartment-style living and many services for the elderly.

assisted reproductive technology (ART) - medical procedures, such as intrauterine insemination, that are performed to help infertile couples conceive.

assistive devices - technical tools and devices such as alphabet boards, text telephones, or text-to-speech conversion software used to assist people with physical or emotional disorders in performing certain actions, tasks, and activities.

asthma - a chronic, inflammatory lung disease characterized by recurrent breathing problems and is usually triggered by allergens. Infection, exercise, cold air, and other factors may also be allergic triggers.

astigmatism - a vision problem that results in blurred images.

asymmetry - lacking symmetry; parts of the body are unequal in shape or size.

asymptomatic - to be without noticeable symptoms of disease.

ataxia - loss of balance.

atherectomy - a non-surgical procedure that involves removing plaque from the walls of arteries with a rotating blade.

atherosclerosis - a type of arteriosclerosis caused by a build-up of plaque in the inner lining of an artery.

athetosis - slow, involuntary movements of the hands and feet.

atonic colon (Also called lazy colon.) - lack of normal muscle tone or strength in the colon caused by the overuse of laxatives or by Hirschsprung's disease; may result in chronic constipation.

atopic dermatitis (Also called eczema.) - a skin disorder that is characterized by itching, scaling, and thickening of the skin; usually located on the face, elbows, knees, and arms.

atresia - lack of a normal opening from the esophagus, intestines, or the anus.

atrioventricular (AV) node - a cluster of cells between the atria and ventricles that regulate the electrical current.

atrioventricular block - an interruption of the electrical signal between the atria and the ventricles.

atrium (atria pl.) - one of two upper chambers in the heart.

atrophic gastritis - chronic inflammation of the stomach lining that causes the breakdown of the mucous membranes of the stomach.

atrophic skin - skin that is thin and wrinkled.

atrophy - wasting away of a body part or tissue.

attention-deficit/hyperactivity disorder (ADHD) - a syndrome (a group of symptoms or signs) that is usually characterized by serious and persistent difficulties, resulting in inattentiveness or distractibility, impulsivity, and hyperactivity.

atypical - not usual; often refers to the appearance of precancerous or cancerous cells.

audiologist - a healthcare professional trained to identify and measure hearing impairments and related disorders using a variety of tests and procedures.

auditory brainstem response (ABR) test - used to test hearing in infants and young children, or to test for brain functioning in unresponsive patients.

auditory nerve - eighth cranial nerve that connects the inner ear to the brainstem.

auditory perception - ability to identify, interpret, and attach meaning to sound.

auditory prosthesis - device that substitutes or enhances the ability to hear.

augmentative devices - tools that help individuals with limited or absent speech to communicate.

aural rehabilitation - techniques used with people who are hearing impaired to improve ability to speak and to communicate.

autism - brain disorder that begins in early childhood and persists throughout adulthood; affects three crucial areas of development: communication, social interaction, and creative or imaginative play.

autoimmune hepatitis - liver disease caused when the body's immune system destroys liver cells for no known reason.

autoimmune process - a process in which the body's immune system attacks and destroys body tissue that it mistakes for foreign matter.

autologous bone marrow transplantation - a procedure in which a patient's own bone marrow is removed, treated with anticancer drugs or radiation, then returned to the patient.

autologous tissue breast reconstruction - the use of the patient’s own tissues to reconstruct a new breast mound. The common technique is the TRAM (transverse rectus abdominous muscle) flap. A TRAM flap involves removing an area of fat, skin, and muscle from the abdomen and stitching it in place to the mastectomy wound.

autopsy - examination of a body after death. Autopsies are performed to determine cause of death, or to verify a diagnosis.

autosomal recessive inheritance - a gene on one of the first 22 pairs of chromosomes, which, when present in two copies, causes a trait or disease to be expressed.

avascular necrosis - death of tissue due to depletion of blood supply.

avoidant personality disorder - persons with this disorder are hypersensitive to rejection and thus, avoid situations with any potential for conflict. This reaction is fear-driven, however, persons with avoidant personality disorder become disturbed by their own social isolation, withdrawal, and inability to form close, interpersonal relationships.

avulsion - when a muscle is forcefully stretched beyond its freely-available range of motion, or when it meets a sudden unexpected resistance while contracting forcefully.

axilla - armpit.

axillary dissection - a surgical procedure in which the lymph nodes in the armpit (axillary nodes) are removed and a microscopic examination is performed.

axon - the long, hair-like extension of a nerve cell that carries a message to the next nerve cell.

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