Med Terms A

5-alpha reductase

A chemical that changes the sex hormone testosterone into a substance called dihydrotestosterone. This hormone can cause the prostate gland to grow abnormally.

abdominal muscles

A flat sheet of muscles on the front of the abdomen, between the ribcage and the pelvis.

abdominoplasty

A procedure to remove excess abdominal skin and tighten the underlying stomach muscles. Also known as a tummy tuck.

abduction

Movement of a body part, such as an arm or leg, away from the center of the body.

ablation

A form of treatment that uses electrical energy, heat, cold, alcohol, or other modalities to destroy a small section of damaged tissue.

abrasion

A scraping or rubbing away of the skin or other surface.

abscess

Pus that collects in a pocket of swollen, red tissue. Often occurs on the surface of the skin.

abutment

A tooth or implant to which a fixed prosthesis is anchored.

acceptance-based therapies

Psychotherapy techniques that use mindfulness to help a person recognize and accept thoughts and feelings but not be controlled by them.

accommodation

The eye's ability to focus on objects that are close.

ACE:

Abbreviation for angiotensin-converting enzyme, an enzyme that converts the inactive form of the protein angiotensin (angiotensin I) to its active form—angiotensin II.

acetabulum

A curved, bowl-shaped depression in the outer part of the hipbone. The ball-shaped portion at the top of the thighbone fits into this space to form the hip joint.

acetaldehyde

The main breakdown product of alcohol metabolism; accumulation of it in the bloodstream may produce flushing (a feeling of heat in the face or chest) and vomiting.

acetaminophen

A common, over-the-counter drug used to reduce fever and relieve mild to moderate pain, but which does not reduce redness or swelling (inflammation).

acetylcholine

A neurotransmitter (a chemical messenger that sends signals between brain cells) that plays roles in attention, learning, and memory.

Achilles’ tendon

A band of connective tissue that connects the calf muscle to the heel bone. This tissue is prone to swelling and/or rupture.

achlorhydria

A condition in which the stomach produces little or no acid. This can affect digestion, cause stomach pain, and keep the body from absorbing vitamins and nutrients.

acne

An inflammatory disease resulting from excess sebum production, follicle plugging, and increased bacterial production.

acquired immunodeficiency syndrome

Usually abbreviated as AIDS. This is the most advanced stage of infection with the human immunodeficiency virus (HIV), which can severely weaken the immune system. People with AIDS get many infections, often from diseases that don’t affect people with healthy immune systems.

acquisition

The term given to the brain's absorption of new information to begin creating a memory.

acromioclavicular joint

A shoulder joint that connects the clavicle to the scapula.

actin

One of the proteins that allows cells to move and muscles to contract.

actinic keratosis

Scaly pink or red-brown raised spots or patches on the skin caused by overexposure to the sun. Actinic keratosis may be a precursor to skin cancer.

active surveillance

A strategy for managing early prostate cancer in which a man has regular checkups but does not undergo treatment until the disease shows signs of worsening.

acupressure

Using the thumb or fingers to apply pressure to particular spots, or pressure points, on the body in order to relieve pain.

acupuncture

A treatment based on Chinese medicine. Thin needles are inserted into the skin at specific points on the body. This therapy is used to treat pain and various health problems and to reduce stress.

acute

A condition that comes on suddenly, often with severe, but short-lived symptoms.

acute pain

Severe pain that occurs suddenly and usually lasts a short while.

acute urinary retention

A sudden inability to empty the bladder. Causes include an enlarged prostate gland (in men) or bladder muscle problems.

adaptability

The ability of an organism to change genetically in a way that allows it to deal better with its environmental conditions.

adaptive immunity

The ability of the body to learn to fight specific infections after being exposed to the germs that cause them

addiction

Loss of control over indulging in a substance or performing an action or behavior, and continued craving for it despite negative consequences.

adduction

Movement of a body part toward or across the midline.

adenocarcinoma

A type of cancer that grows in the layer of tissue known as the epithelium. This tissue lines organs and structures in the body, protecting or enclosing them.

adenoma

A benign growth found in the layer of cells that lines certain organs (epithelial cells).

adenosine triphosphate

An energy-storing molecule that is found in all human cells. Usually abbreviated as ATP.

adequate intake

An estimate of the amount of a nutrient needed by healthy people. The Adequate Intake is used when there isn’t enough information to set a recommended dietary allowance (RDA).

adhesion

A band of scar-like tissue that forms between two surfaces inside the body, connecting tissues or organs which are not normally connected.

adipose tissue

Fat-filled tissue.

adjuvant therapy

Extra therapy given after a primary treatment, to increase the effectiveness of the primary treatment. For example, using chemotherapy after surgery or radiation treatment for cancer.

adrenal glands

Glands that sit on top of each kidney and secrete stress hormones.

adrenaline

Stress hormone that puts the body on high alert. Changes include faster heartbeat, more rapid breathing, greater energy, and higher blood pressure. Also called epinephrine.

adult day services

Centers providing daytime services to adults who need supervision, social support, or assistance with daily activities.

adulterant

An ingredient in a medicinal product (herb, supplement, or prescription drug), which dilutes the purity of the product and does not contribute to its therapeutic effects.

advance care directive (or advance medical directive)

A legal document that describes the kind of medical care a person want if an accident or illness leaves him or her unable to make or communicate decisions.

advanced sleep phase syndrome

A pattern of falling asleep and waking up earlier than wanted that worsens progressively over time.

aerobic

Any process that requires oxygen. Often used to describe a form of exercise, aerobic exercise.

aerobic exercise

Physical activity that speeds breathing, improves heart and lung function, and offers many other health benefits. Examples include brisk walking, running, or cycling

aerophagia

Excessive swallowing of air.

aesthetician

Licensed skin care professional who performs procedures such as deep cleansing, low-grade chemical peels, microdermabrasion, and postsurgical skin care.

after-cataract

Clouding of the lens of the eye that can occur months or years after cataract surgery.

age-related cognitive decline

The slight loss of memory and slowing of the brain’s information processing that occurs with normal aging.

age-related macular degeneration

A potentially blinding condition that destroys sharp central vision.

agnosia

A rare disease in which a person can’t recognize objects, shapes, or people. Often due to a brain or neurological condition.

agonist

1) A substance that triggers a physiological response when it combines with a receptor. 2) A muscle whose contraction is opposed by another muscle.

agoraphobia

Fear and avoidance of public places and open spaces.

AIDS

abbreviation for acquired immunodeficiency syndrome, the most advanced stage of infection with the human immunodeficiency virus (HIV).

AIDS dementia

A loss of brain function that occurs rapidly in some AIDS patients; marked by forgetfulness, difficulty thinking, and trouble focusing.

albinism

A group of inherited conditions that typically appear as a reduction or absence of melanin pigments in the skin, hair, and eyes.

albumin

A protein made by the liver. Abnormal levels of this substance may indicate liver or kidney disease.

albuminuria

High amounts of albumin (a protein made by the liver) in the urine, possibly indicating kidney dysfunction.

alcohol abuse

Continuing consumption of alcohol despite alcohol-related social or interpersonal problems.

alcohol dehydrogenase

A liver enzyme that metabolizes alcohol into a substance called acetaldehyde, which is toxic. Sometimes referred to as ADH.

alcohol dependence

A chronic, progressive disease characterized by excessive and often compulsive drinking, impaired control over drinking, use of alcohol despite adverse consequences, and withdrawal symptoms when alcohol use is discontinued. Also known as alcoholism.

alcoholism

Another term for alcohol dependence: A chronic, progressive disease characterized by excessive and often compulsive drinking, impaired control over drinking, use of alcohol despite adverse consequences, and withdrawal symptoms when alcohol use is discontinued. Also known as alcoholism.

aldosterone

A hormone secreted by the adrenal glands that helps regulate blood pressure by controlling sodium and potassium levels in the body.

alendronate

A drug used to treat and prevent osteoporosis by slowing bone loss.

alimentary canal

Another term for the gastrointestinal, or digestive, tract.

allele

One of two or more versions of a gene. Different alleles produce variations in inherited characteristics, such as eye color.

allergic

Having a sensitivity to one or more normally harmless substances.

allergic rhinitis

A seasonal or year-round allergic condition marked by sneezing, runny nose, and congestion. The most common type of allergy, it is caused by an IgE-mediated immune response to inhaled airborne allergens.

allergy

An immune system reaction (for example, rash, fever, sneezing, or headaches) to something that is normally harmless.

allodynia

Pain resulting from something not normally painful, such as a light touch.

alopecia areata

An autoimmune condition that appears as patchy hair loss on the scalp that may result in permanent hair loss.

alopecia totalis

Hair loss that involves the entire scalp.

alopecia universalis

Hair loss that involves the entire body.

alpha blockers

A group of drugs that lower blood pressure by blocking the effects of adrenaline or adrenaline-like substances on cells' alpha receptors. Also used to treat some prostate gland problems. Alpha blockers are also known as alpha-adrenergic antagonists, alpha-adrenergic blocking agents, and alpha-adrenergic blockers.

alpha cells

Cells in the pancreas that produce the hormone glucagon.

alpha hydroxy acids

Fruit-derived acids used in creams and lotions to act as exfoliants.

alpha waves

A type of brain wave generated when a person is relaxed, awake, and receiving no visual input (eyes closed or in the dark).

alpha-delta sleep

Abnormal deep sleep; also called non-restorative sleep.

alpha-glucosidase inhibitor

A drug used to treat Type 2 diabetes

alveolar bone

The part of the jawbone that supports the teeth.

alveoli

Tiny air sacs in the lung. They are where oxygen enters and carbon dioxide leaves the bloodstream.

Alzheimer's disease

A progressive brain disease that causes memory loss, impaired thinking, and personality changes.

ambulatory

Able to walk; not confined to a bed.

AMD

Abbreviation for age-related macular degeneration, a potentially blinding condition that destroys sharp central vision.

amnesia

Unusual memory loss or forgetfulness.

Amsler grid

A tool used to check for vision problems, particularly macular degeneration. The grid looks like graph paper with a dot in the center.

amygdala

Part of the brain involved in memory and emotion

amylase

An enzyme secreted by the pancreas that breaks starch into sugar.

amyloid

A protein that collects in tissues when certain diseases, including Alzheimer’s disease, are present.

anaerobic

Any process that doesn’t require oxygen. Often refers to a form of short, high intensity exercise, known as anaerobic exercise.

anaerobic exercise

Exercise that improves the efficiency of energy-producing systems that do not rely on oxygen. Examples include sprinting and weight lifting.

anagen

The active growth phase of the hair-growth cycle.

anal canal

The last inch of the large intestine, leading to the anal opening.

analgesia

Absence of pain.

analgesic

A drug or other substance such as aspirin, acetaminophen, or morphine that is used to relieve pain.

analytic variability

Differences in how a test is done, for example how a sample is prepared, which can affect test outcomes.

anaphylaxis

A severe allergic reaction, causing symptoms spanning from itching and swelling to trouble breathing, convulsions, shock, and coma.