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Glossary - All

Displaying glossary terms: 201 - 250 of 2011 in total
atrioventricular (AV) node
A major part of the electrical system in the heart that acts as a gateway between the atria and the ventricles. An electrical signal generated by the sinoatrial node (the heart's natural pacemaker) moves through the heart until it reaches the atrioventricular node, a cluster of cells at the bottom of the right atrium. The AV node delays the signal before it is passed to the ventricles. This lets the atria fully contract before the ventricles contract.
atrium
One of the two upper chambers of the heart.
atrium (plural, atria)
One of the heart's two upper chambers. The right atrium receives deoxygenated blood from the body; the left atrium receives oxygenated blood from the lungs.
atrophy
Wasting away of an organ or tissue due to undernourishment, disease, or aging.
atypical lobular hyperplasia
An overgrowth of abnormally shaped cells in areas of the breast that produce milk (lobules). atypical lobular hyperplasia is not cancerous but may become cancer.
audiogram
A chart that shows a person's ability to hear at different pitches or frequencies.
audiologist
A health professional who assesses hearing and fits hearing aids.
Related health topics: Hearing Loss in Adults
audiometry
A complete hearing test that involves listening to sounds of different frequencies and volume.
auditory nerve
A nerve in the inner ear that transmits information about sound to the brain.
aura
Sensations such as chills, flashes of light, or a blind spot that come just before the occurrence of medical problems such as migraines or seizures.
autoantibodies
Proteins created by the immune system that mistakenly target healthy cells, tissues, or organs.
autoimmune disease
A disease in which the immune system mistakenly identifies healthy tissues and organs as threats and responds by attacking and destroying them.
autoimmune response
When the body's immune system mistakenly views the body's own tissues and organs as foreign invaders and attacks them.
autologous fat transplant
Removal of fat from one part of the body to use as filler in another part, for example, to fill wrinkles and lines in the face and lips.
autonomic nervous system
The part of the nervous system that controls involuntary actions, such as blood pressure or breathing. It also plays an important role in the fight or flight response to danger.
autonomic neuropathy
Damage to the nerves that control involuntary body functions, such as digestion, heart rate, and bladder and bowel function.
autopsy
Surgically opening and examining a body after death to see if any diseases are present and to determine the cause of death.
avulsion
The tearing away of one part of the body from another?for example, a tendon tearing away from a bone.
axillary
The armpit.
axis
The second vertebra of the neck (from the skull); also called the C-2 vertebra.
axon
The long, slender extension of a nerve cell that conducts electrical impulses away from the nerve's cell body and on to nearby nerves.
axon terminal
The end of an axon.
B cell
White blood cells that come from bone marrow, and produce antibodies to fight off disease.
bacteria
Tiny single-celled organisms. Some bacteria cause disease, although most are harmless.
balance
Ability to maintain equilibrium while stationary or moving.
balloon angioplasty
A procedure to open clogged heart arteries. A surgeon inserts and inflates a tiny balloon. It widens the blocked artery then expands a small wire mesh tube to keep the artery open.
balloon dilation
A surgical procedure to open a narrowed vessel or tube, such as the urethra, esophagus, or artery. A small, deflated balloon is inserted into the area and inflated to widen it.
bariatric surgery
One of several types of weight loss surgery performed on people who are dangerously overweight, to restrict or reduce food intake and/or absorption.
barium study
An imaging test that allows doctors to see the inside of the esophagus and upper stomach. It involves swallowing a barium solution, which coats the esophagus and makes it possible for x-rays to see the inside of the intestine.
Barrett's esophagus
The abnormal growth of stomach or small intestine cells in the esophagus, resulting from damage caused by the reflux of stomach acid; occasionally may transform into cancer.
basal cell carcinoma
The most common skin cancer. Basal cell carcinoma doesn't spread to internal organs.
basal ganglia
Clusters of nerve cells deep in the brain that play an important role in movement.
Related health topics: Stroke Overview
baseline EKG
An electrocardiogram (EKG) tracing taken in a healthy individual for later comparison to subsequent EKGs.
basilar artery
The artery that supplies blood to the cerebellum, the brainstem, and the back of the brain.
benign
Harmless; often used to refer to a tumor that is not cancerous and does not usually spread.
Related health topics: Prostate Cancer
benign orgasmic headache
A severe headache that occurs when orgasm is reached.
benign prostatic hyperplasia (BPH)
A noncancerous enlargement of the prostate gland that obstructs the flow of urine.
benzodiazepines
Anti-anxiety medications that work by helping to maintain levels of the neurotransmitter GABA in the brain.
bereavement
The period of grief and mourning after a death.
beriberi
A nervous system or heart disorder caused by lack of the vitamin thiamine (B1).
Bernstein test
A test to try to reproduce heartburn symptoms; used by doctors to diagnose GERD (gastroesophageal reflux disease).
beta blockers
Medications that block epinephrine (adrenaline) and norepinephrine from attaching to certain parts of nerve cells known as beta receptors. Used to treat high blood pressure, heart rhythm problems, migraines, panic attacks, and other conditions.
beta carotene
A richly colored compound (red, yellow, or orange) found in many plants, fruits, and vegetables that the body can convert into vitamin A.
beta cells
Cells that make and secrete insulin; located in the islets of Langerhans of the pancreas.
beta-agonists
A medication that opens airways by relaxing the muscles around the airway; used to treat asthma or COPD (chronic obstructive pulmonary disease).
beta-amyloid
An abnormal protein deposited in the brain in Alzheimer's disease.
beta-blockers
A class of drugs that slow the heartbeat, lessen the force of each contraction, and reduce the contraction of blood vessels in the heart, brain, and throughout the body by blocking the action of beta-adrenergic substances such as adrenaline (epinephrine) at the beta receptor. Beta blockers, also known as beta-adrenergic blocking agents, are used to treat many cardiovascular conditions, including abnormal heart rhythms, angina, and high blood pressure. They also improve survival after a heart attack.
biguanides
Medications that stop the liver from making excess glucose (sugar) and improve sensitivity to insulin.
bile
A thick, yellow-green fluid produced by the liver that aids in digestion.
Related health topics: Liver Cancer, Pancreatic Cancer
bile acids
Fatty substances made by the gallbladder that aid in digestion.