Definition Ayurvedic medicine is a system of healing that originated in ancient India. In Sanskrit, ayur means life or living, and veda means knowledge, so Ayurveda has been defined as the "knowledge of living" or the "science of longevity." Ayurvedic medicine utilizes diet, detoxification and purification techniques, herbal and mineral remedies, yoga, breathing exercises, meditation, and...

Definition Also known as aerospace medicine, flight medicine, or space medicine, aviation medicine is a medical specialty that focuses on the physical and psychological conditions associated with flying and space travel. Purpose Since flying airplanes and spacecraft involves great risk and physical demands, such as changes in gravity and oxygen, pilots and astronauts need medical experts to protect their safety...

Autopsy means "see for yourself." It is a special surgical operation, performed by specially trained physicians, on a dead body. Its purpose is to learn the truth about the person's health during life, and how the person died. There are many advantages to getting an autopsy. Even when the law does not require it, there is always something interesting for the family to know—something worth...

Autoimmunity is a condition in which the immune system mistakenly recognizes host tissue or cells as foreign. (The word “auto” is the Greek word for self.) Because of this false recognition, the immune system reacts against the host components. There are a variety of autoimmune disorders (also called autoimmune diseases). An autoimmune disease can be very specific, involving a single organ. Three...

Definition Autism is a chronic and often severe disorder of brain functioning that begins during childhood. It is marked by problems with social contact, intelligence, and language, coupled with ritualistic or compulsive behavior, sensory integration and processing problems, and strange environmental responses. Description Autism is a lifelong disorder that interferes with the ability to understand what is...

Definition Auditory integration training (AIT), is one specific type of music/auditory therapy based upon the work of French otolaryngologists Dr. Alfred Tomatis and Dr. Guy Berard. Origins The premise upon which most auditory integration programs are based is that distortion in how things are heard contributes to commonly seen behavioral or learning disorders in children. Some of these disorders include attention...

Definition Audiometry encompasses those procedures used to measure hearing thresholds. Purpose The purpose of audiometry is to establish an individual's range of hearing. It is most often performed when hearing loss is suspected. Audiometry can establish the extent as well as the type of a hearing loss. Audiometric techniques are also used when an individual has vertigo or dizziness , since many hearing...

What is ADHD? ADHD is a disorder that affects 5% to 7% of children. Children with ADHD have problems with attention span, hyperactivity, and impulsive behavior. ADHD is the term now used for ADD (Attention Deficit Disorder). ADHD is more common in boys than in girls. A normal attention span is 3 to 5 minutes per year of a child's age. Therefore, a 2-year-old should be able to concentrate on a particular...

Definition An atrial septal defect (ASD) is an abnormal opening in the muscular wall separating the left and right upper chambers (atria) of the heart. Description During normal development of the fetal heart, there is an opening in the wall (septum) separating the left and right upper chambers of the heart. Normally, the opening closes before birth, but if it does not, the child is born with a hole between...

Definition Atrial fibrillation and flutter are abnormal heart rhythms in which the atria, or upper chambers of the heart, are out of sync with the ventricles, or lower chambers of the heart. In atrial fibrillation, the atria "quiver" chaotically and the ventricles beat irregularly. In atrial flutter, the atria beat regularly and faster than the ventricles. Description Atrial fibrillation and flutter...

Definition Atrial ectopic beats (AEB) refers to a contraction of the upper heart chamber which occurs before it would be expected. Atrial ectopic beats are also known as premature atrial beats, premature atrial complex (PAC), or atrial extrasystole. Description An AEB is usually a harmless disturbance in the normal rhythm of the heart. It can occur only occasionally, in a regular pattern, or several may occur...

Definition Eczema is a general term used to describe a variety of conditions that cause an itchy, inflamed skin rash. Atopic dermatitis, a form of eczema, is a non-contagious disorder characterized by chronically inflamed skin and sometimes intolerable itching. Description Atopic dermatitis refers to a wide range of diseases that are often associated with stress and allergic disorders that involve the respiratory...

Definition The Atkins diet is a high-protein, high-fat, very low-carbohydrate regimen. It emphasizes meat, cheese, and eggs, while discouraging foods such as bread, pasta, fruit, and sugar. It is a form of ketogenic diet. Origins Robert C. Atkins, a cardiologist and internist, developed the diet in the early 1970s. It first came to public attention in 1972 with the publication of Dr. Atkins' Diet Revolution....

Definition Athletic heart syndrome is the adaptation of an athlete's heart in response the physiologic stresses of strenuous physical training. It can be difficult to distinguish a significant medical condition from an athletic heart. Description The heart adapts to physical demands by enlarging, especially the left ventricle. Enlargement increases the cardiac output, the amount of blood pumped with each...

Definition Atherosclerosis is the build up of plaque on the inside of blood vessels. Atherosclerosis is often called arteriosclerosis, which is a general term for hardening of the arteries. Description Atherosclerosis, a progressive condition responsible for most heart disease , is a type of hardening of the arteries. It can be caused by normal aging processes, by high blood pressure, and by some diseases,...

What is atherectomy? An atherectomy is a procedure to remove plaque from an artery. Plaque is a buildup of fats and cholesterol, called an atheroma, that partly or completely blocks blood flow through an artery. Removing an atheroma used to require opening the chest and the artery. Now, however, a device can be inserted in a groin artery which can then be directed to atheromas in the heart arteries or in blood...

Definition Atelectasis is a collapse of lung tissue affecting part or all of one lung. This condition prevents normal oxygen absoption to healthy tissues. Description Atelectasis can result from an obstruction (blockage) of the airways that affects tiny air scas called alveoli. Alveoli are very thin-walled and contain a rich blood supply. They are important for lung function, since their purpose is the exchange...

  Definition Ataxia-telangiectasia (A-T), also called Louis-Bar syndrome, is a rare, genetic neurological disorder of childhood that progressively destroys part of the motor control area of the brain, leading to a lack of balance and coordination. A-T also affects the immune system and increases the risk of leukemia and lymphoma in affected individuals. Description The disorder first appeared in the medical...

Definition Aston-Patterning is an integrated system of movement education, bodywork, ergonomic adjustments, and fitness training that recognizes the relationship between the body and mind for well being. It helps people who seek a remedy from acute or chronic pain by teaching them to improve postural and movement patterns. Origins Aston-Patterning is a process originated by Judith Aston in 1977. After graduating...

What is astigmatism? Astigmatism is distorted vision caused by an irregular curvature of the front surface of the eye (the cornea). As a result of astigmatism, some images are more in focus in one direction than in another. A person with astigmatism might not see vertical lines clearly. Horizontal lines may be fuzzy to another person with astigmatism, while a third may have trouble seeing diagonal lines. A...

Definition Asthma is a chronic (long-lasting) inflammatory disease of the airways. In people susceptible to asthma, this inflammation causes the airways to narrow periodically. This narrowing, in turn, produces wheezing and breathlessness that sometimes causes the patient to gasp for air. Obstruction to air flow either stops spontaneously or responds to a wide range of treatments, but continuing inflammation...

Definition Aspirin is a medication given to relieve pain and reduce fever. The name "aspirin" was originally a trademark, first used when the drug was introduced in Europe in 1899. Aspirin was developed by a German chemist named Felix Hoffman as a treatment for his father's arthritis. Purpose Aspirin is still used to relieve many kinds of minor aches and pains—headaches, toothaches, muscle...

Definition Aspergillosis refers to several forms of disease caused by a fungus in the genus Aspergillus. Aspergillosis fungal infections can occur in the ear canal, eyes, nose, sinus cavities, and lungs. In some individuals, the infection can even invade bone and the membranes that enclose the brain and spinal cord (meningitis ). Description Aspergillosis is primarily an infection of the lungs caused by the...

Definition The Aspartate aminotransferase test measures levels of AST, an enzyme released into the blood when certain organs or tissues, particularly the liver and heart, are injured. Aspartate aminotransferase (AST) is also known as serum glutamic oxaloacetic transaminase (SGOT). Purpose The determination of AST levels aids primarily in the diagnosis of liver disease. In the past, the AST test was used to...

In medicine (gastroenterology), ascites (also known as peritoneal cavity fluid, peritoneal fluid excess, hydroperitoneum or more archaically as abdominal dropsy) is an accumulation of fluid in the peritoneal cavity. Although most commonly due to cirrhosis and severe liver disease, its presence can portend other significant medical problems. Diagnosis of the cause is usually with blood tests, an ultrasound scan...

Asbestos is a mineral rock with a chemical composition of mostly silicon, water, and magnesium. Most asbestos fibers are long, thin, strong, flexible, fireproof, and resistant to chemical attack. Of the six varieties of asbestos fibers found in nature, only three are commonly found in construction materials: chrysotile, amosite, and crocidolite. Chrysotile, the variety most often found in building materials,...

Definition Arthroscopy is the examination of a joint, specifically, the inside structures. The procedure is performed by inserting a specifically designed illuminated device into the joint through a small incision. This instrument is called an arthroscope. The procedure of arthroscopy is primarily associated with the process of diagnosis. However, when actual repair is performed, the procedure is called arthroscopic...

Definition Arthroscopic surgery is a procedure that allows surgeons to visualize, diagnose, and treat joint problems. The name is derived from the Greek words arthron, joint, and skopein, to look at. Arthroscopy is performed using an arthroscope, a small fiber-optic instrument that enables a close look at the inside of a joint through a small incision. Purpose Arthroscopic surgery is used to diagnose, treat,...

Definition Arthroplasty is surgery performed to relieve pain and restore range of motion by realigning or reconstructing a dysfunctional joint. Purpose The goal of arthroplasty is to restore the function of a stiffened synovial joint and relieve pain. As a surgical procedure, it is usually performed when medical treatment has not improved function in the affected joint. There are two types of arthroplastic...

Definition Arthrograpy is a procedure involving multiple x rays of a joint using a fluoroscope, or a special piece of x-ray equipment which shows an immediate x-ray image. A contrast medium (in this case, a contrast iodine solution) injected into the joint area helps highlight structures of the joint. Purpose Frequently, arthrography is ordered to determine the cause of unexplained joint pain. This fluoroscopic...

Definition Arteriovenous malformations (AVMs) are blood vessel defects that occur before birth when the fetus is growing in the uterus (prenatal development). The blood vessels appear as a tangled mass of arteries and veins. They do not possess the capillary (very fine blood vessels) bed that normally exists in the common area where the arteries and veins lie in close proximity (artery-vein interface). An arteriovenous...

Definition An arteriovenous fistula is an abnormal channel or passage between an artery and a vein. Description An arteriovenous fistula is a disruption of the normal blood flow pattern. Normally, oxygenated blood flows to the tissue through arteries and capillaries. Following the release of oxygen in the tissues, the blood returns in veins to the heart. An arteriovenous fistula is an abnormal connection of...

Definition An embolus is a blood clot, bit of tissue or tumor, gas bubble, or other foreign body that circulates in the blood stream until it becomes stuck in a blood vessel. Description When a blood clot develops in an artery and remains in place, it is called a thrombosis. If all or part of the blockage breaks away and lodges in another part of the artery, it is called an embolism. Blockage of an artery in...

Definition Art therapy, sometimes called creative arts therapy or expressive arts therapy, encourages people to express and understand emotions through artistic expression and through the creative process. Origins Humans have expressed themselves with symbols throughout history. Masks, ritual pottery, costumes, other objects used in rituals, cave drawings, Egyptian hieroglyphics, and Celtic art and symbols...

Definition An arrhythmia is an abnormality in the heart's rhythm, or heartbeat pattern. The heartbeat can be too slow, too fast, have extra beats, skip a beat, or otherwise beat irregularly. Description Arrhythmias are deviations from the normal cadence of the heartbeat, which cause the heart to pump improperly. The normal heartbeat starts in the right atrium, where the heart's natural pacemaker (the...

Term used for treatment of illness and maintenance of general physical health using essential oils distilled from plants. Virtually unknown to the modern world twenty years ago, aromatherapy is now considered the fastest growing natural healing art in the United States. Aromatherapy treatments were known in ancient Egypt, Greece, Rome, and other civilizations, while early Arabian physicians developed the distillation...

Definition Encephalitis is a serious inflammation of the brain, Arbovirus encephalitis is caused by a virus from the Arbovirus group. The term arbovirus stands for Arthro-pod-borne virus because these viruses are passed to humans by members of the phylum Arthropoda (which includes insects and spiders). Description Of the huge number of arboviruses known to exist, about 80 types are responsible for human disease....

Definition Apraxia is neurological condition characterized by loss of the ability to perform activities that a person is physically able and willing to do. Description Apraxia is caused by brain damage related to conditions such as head injury, stroke, brain tumor, and Alzheimer's disease. The damage affects the brain's ability to correctly signal instructions to the body. Forms of apraxia include...

Definition Appetite-enhancing drugs are a diverse group of medications given to prevent undesired weight loss in the elderly and in patients suffering from such diseases as AIDS and cancer, which often result in wasting of the body's muscle tissue as well as overall weight loss. The medical term for these drugs is orexigenic, which is derived from the Greek word for "appetite" or "desire."...

Definition Appendicitis is an inflammation of the appendix, which is the worm-shaped pouch attached to the cecum, the beginning of the large intestine. The appendix has no known function in the body, but it can become diseased. Appendicitis is a medical emergency, and if it is left untreated, the appendix may rupture and cause a potentially fatal infection. Description Appendicitis is the one of the most common...

Definition Appendectomy is the surgical removal of the appendix. The appendix is a worm-shaped hollow pouch attached to the cecum, the beginning of the large intestine. Purpose Appendectomies are performed to treat appendicitis, an inflamed and infected appendix. Precautions Since appendicitis occurs most commonly in males between the ages of 10-14 and in females between the ages of 15-19, appendectomy is most...

Definition Aplastic anemia is a disorder in which the bone marrow greatly decreases or stops production of blood cells. Description The bone marrow (soft tissue that is located within the hard outer shell of the bones) is responsible for the production of all types of blood cells. The mature forms of these cells include red blood cells, which carry oxygen throughout the body; white blood cells, which fight...

Definition Aphasia is a communication disorder that occurs after language has been developed, usually in adulthood. Not simply a speech disorder, aphasia can affect the ability to comprehend the speech of others, as well as the ability to read and write. In most instances, intelligence per se is not affected. Description Aphasia has been known since the time of the ancient Greeks. However, it has been the focus...

Definition The Apgar scoring system evaluates the physical condition of the newborn at one minute after birth and again at five minutes after birth. The newborn receives a total score (Apgar score) that ranges from 0 to 10 based on rating color, heart rate, respiratory effort, muscle tone, and reflex irritability. Purpose Virginia Apgar specialized in anesthesiology and childbirth . She developed the Newborn...

Definition The aortic valve separates the left ventricle of the heart (the heart's largest pumping chamber) from the aorta, the large artery that carries oxygen-rich blood out of the left ventricle to the rest of the body. In aortic valve insufficiency, the aortic valve becomes leaky, causing blood to flow backwards into the left ventricle. Description Aortic valve insufficiency occurs when this valve cannot...

Definition When aortic valve stenosis occurs, the aortic valve, located between the aorta and left ventricle of the heart, is narrower than normal size. Description A normal aortic valve, when open, allows the free flow of blood from the left ventricle to the aorta. When the valve narrows, as it does with stenosis, blood flow is impeded. Because it is more difficult for blood to flow through the valve, there...

Definition Aortic dissection is a rare, but potentially fatal, condition in which blood passes through the inner lining and between the layers of the aorta. The dissecting aorta usually does not burst, but has an abnormal second channel within it. Description A defect in the inner lining of the aorta allows an opening or tear to develop. The aorta is the main artery of the body and is an area of high blood...

Definition An aneurysm is an abnormal bulging or swelling of a portion of a blood vessel. The aorta, which can develop these abnormal bulges, is the large blood vessel that carries oxygen-rich blood away from the heart to the rest of the body. Description The aorta carries oxygen-rich blood to the body, and is therefore called an artery. Because the aorta is an artery, its walls are made of up three layers;...

Definition The anxiety disorders are a group of mental disturbances characterized by anxiety as a central or core symptom. Although anxiety is a commonplace experience, not everyone who experiences it has an anxiety disorder. Anxiety is associated with a wide range of physical illnesses, medication side effects, and other psychiatric disorders. The revisions of the Diagnostic and Statistical Manual of Mental...

Anxiety is a universally experienced emotion felt as an unpleasant, tense anticipation of an impending but vague threat. Some 18 percent of the adult U.S. population experiences anxiety symptoms to the extent that they can be diagnosed as suffering from an anxiety disorder. Anxious people often feel as if something bad were about to happen to them, although they might be unable to identify an immediate threat....