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Glossary - R

Displaying glossary terms beginning with the letter R: 1 - 50 of 87 in total
radial tunnel syndrome
A condition in which the radial nerve is compressed at the elbow, causing pain, numbness, tingling, and muscle weakness in the hand and arm.
radiation
Energy in the form of particles or waves, such as x-rays and gamma rays. Radiation is often used to help make a diagnosis, as in x-rays, or as a treatment for cancer.
radiation therapy
Treatment with high-energy rays (from x-rays or other sources) designed to control disease and destroy cancer cells.
radical prostatectomy
Surgery to remove the entire prostate.
radiculopathy
Pain caused by irritation of a nerve as it exits the spinal cord.
radioactive iodine
A radioactive form of iodine that can be used as a tracer during a radioactive iodine uptake test or a radioactive thyroid scan. Much larger amounts are used in the treatment of hyperthyroidism.
radiofrequency
A non-surgical technique using an electromagnetic current to penetrate deep into the body's tissues, which can be used to treat pain, cancer, and heart rhythm disorders, among other conditions.
radiograph
Another name for an x-ray.
radionuclide imaging or scan
Another name for nuclear tests: tests that use tiny amounts of short-lived radioactive substances that can target particular organs or cell receptors to diagnose disease.
radionuclides
Short-lived radioactive chemicals that are used in nuclear imaging tests.
Related health topics: Cardiomyopathy
rales
Abnormal lung sounds that might be a sign of fluid buildup congestion in the lungs.
randomized
A feature of many clinical trials in which participants are randomly assigned to either a group to be tested or a control group.
randomized, controlled clinical trial
A study in which researchers choose a study population at random; one group receives the intervention (such as a nutritional supplement) and another group receives a placebo.
range of motion
The extent of movement?and thus flexibility?in a joint, measured in the degrees of a circle.
rapid eye movement (REM) sleep
A period of intense brain activity during sleep, often associated with dreams; named for the rapid eye movements that occur during this time. Also called dreaming sleep.
RAST (radioallergosorbent test)
A blood test used for identifying allergens.
Raynaud's syndrome
A condition in which the blood vessels in the fingers and other extremities narrow in response to cold or stress, causing them to turn white or blue.
reactive arthritis
Joint problems triggered by bacterial or viral infection elsewhere in the body.
rebound insomnia
Insomnia caused by withdrawal from sleep medication; usually it is at least as serious as before the medication was used.
Related health topics: Tendonitis
receptors
Structures on the outside of a cell membrane that permit attachment of specific chemicals.
recessive
A gene that will not be expressed in the offspring unless it is inherited from both the mother and father. A recessive gene from one parent that is paired with a dominant gene from the other parent will be overridden by the dominant gene.
recombinant tissue plasminogen activator (tPA)
A thrombolytic (clot-dissolving) drug made using recombinant DNA technology; used to dissolve blood clots causing an ischemic stroke, pulmonary embolism, or myocardial infarction.
recommended dietary allowance (RDA)
The average daily amount of a nutrient that will meet the nutritional needs of almost all (97%?98%) healthy people at specific stages of their lives.
recovery
A process of overcoming addiction to alcohol, other psychoactive substance, or addictive behavior. Often this involves a commitment to abstinence, but sometimes it involves reduced use rather than complete abstinence.
rectocele
A weakening of the vaginal wall that allows the rectum to bulge into the vagina.
rectum
The last 12 centimeters of the colon, through which waste is eliminated from the body.
refraction
The deflection of light as it passes through one medium to another of different density; also refers an eye test to evaluate the eye's ability to focus.
regurgitation
Leakage of blood back into a heart chamber that occurs when a heart valve doesn't close properly
rehabilitative driving specialist
A professional trained to evaluate driving skills and, when appropriate, suggest equipment and adaptations to make driving safer for people with certain physical or mental limitations.
rejection
A reaction that occurs when a person's immune system recognizes a transplanted organ as a threatening substance and tries to rid the body of it.
relapse
The return of symptoms and disease after a person seems to have recovered.
relaxation response
The physical effects of meditation and certain other techniques that are opposite to those of the stress response. Effects include marked drops in oxygen consumption, carbon dioxide expiration, heartbeat, and respiration, as well as stabilization or lowering of blood pressure.
Related health topics: Bulimia
REM behavior disorder
A sleep disorder marked by movement during REM sleep, when muscles are normally paralyzed.
REM rebound
An increase in REM sleep, often with nightmares, that occurs after deprivation of REM sleep or the withdrawal of REM-suppressing medications.
remission
A lessening in the severity of a disease and its symptoms. In cancer, a reduction in the size of a tumor and its symptoms.
remodeling
Altering a body part. Bone is constantly being remodeled in response to exercise or inactivity. Heart tissue is remodeled in response to a heart attack or high blood pressure.
renal
Pertaining to the kidneys.
renal artery stenosis
Narrowing of an artery that supplies blood to the kidney.
renin
An enzyme released by the kidney that stimulates production of angiotensin and aldosterone, two substances in the body that affect blood pressure.
reperfusion
Re-establishing blood flow, such as when a blockage in a coronary artery that is causing a heart attack is cleared.
reperfusion therapy
Techniques used to restart circulation to part of the heart or brain that has been cut off from blood flow during a heart attack or stroke. Reperfusion may entail clot-dissolving drugs, balloon angioplasty, or surgery.
repetitions (rep)
Number of times an exercise calls for a muscle to be worked and released (usually eight to 12).
resection
The surgical removal of a lesion or part or all of an organ or other body structure.
resectoscope
An instrument that permits a surgeon to view the inside of a body cavity in order to remove a part of an organ or structure.
reservoir
The habitat in which an infectious agent normally lives, grows, and multiplies. Reservoirs include human, animal, and environmental reservoirs.
resilience
The ability to adapt to change and recover quickly from setbacks such as illness, injury, or misfortune.
resistance
The ability of a pathogen to withstand drugs previously effective against them. Usually the result of genetic mutation.
resistant hypertension
High blood pressure that does not respond to drug therapy and lifestyle changes.
resorption
The removal of bone tissue, both mineral and protein, by osteoclasts.
respiration
The process by which gases enter the body, including external respiration (breathing), and internal respiration, in which oxygen taken in by the lungs is carried by the blood to tissues and carbon dioxide is removed.