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atoms

The smallest units of an element.

atria

The two upper chambers of the heart.

atrial fibrillation

A common abnormal heart rhythm causing a rapid, irregular pulse and failure of the upper chambers of the heart (atria) to pump properly. Abbreviated to AF.

atrial flutter

An abnormally fast but regular heart rhythm due to disturbances in the biological electrical system of the atria of the heart. It is a type of supraventricular tachycardia

atrial septal defect

A hole in the wall separating the two upper chambers of the heart (atria), present from birth. Abbreviated to ASD.

atrioventricular block

A block in the normal conduction of electrical activity between the upper and lower chambers of the heart (atria and ventricles).

atrium

One of the two upper chambers of the heart.

atrophic

Relating to atrophy.

atrophic rhinitis

Rhinitis due to atrophy of the mucous membrane lining the nose, causing it to become thin, dry and crusty.

atrophic vaginitis

Inflammation of the vagina.

atrophy

Withering or weakening of a body tissue due to disease or disuse.

attenuated

A microbe that has been treated so as to be less able to cause disease. Attenuated bacteria or viruses are used in many immunisations, to stimulate the body's immune system against a disease without actually causing that disease.

attenuation

Treatment of a microbe so that it is less able to cause disease. Attenuated bacteria or viruses are used for many immunisations, to stimulate the body's immune system against a disease without actually causing that disease.

audiometry

The measurement of hearing.

auditory

Relating to the sense of hearing.

autoantibody

An antibody directed against the body's own tissues, typically produced in autoimmune disorders

autoantibody test

A laboratory test used to help diagnose autoimmune disorders.

autoimmune

Any condition caused by the body’s immune response against its own tissues.

autoimmune screen

A test that help to diagnose disorders caused by a reaction of the immune system against the body's own cells and tissues.

autonomic

The part of the nervous system supplying muscles such as the heart and bowels, known as involuntary muscles.

avascular necrosis

A disease that results from the temporary or permanent loss of blood supply to the bones.

AXR

An abbreviation for abdominal x-ray.

ayurveda

An ancient system of Indian medicine.

bacteria

A group of organisms too small to be seen with the naked eye, which are usually made up of just a single cell.