Abdominal cavity

the part of the body between the bottom of the ribs and the top of the thighs, containing most of the digestive and urinary systems along with some reproductive organs

ABO blood groups

The system by which human blood is classified, based on proteins occurring on red blood cells; the four classification groups are A, AB, B, and O


termination of a pregnancy; can occur because of natural causes (called a miscarriage) or be a medical intervention


an accumulation of pus in a body tissue, usually caused by a bacterial infection

ACE inhibitor

a drug typically used to treat high blood pressure (Angiotensin-Converting Enzyme inhibitor)

Achilles tendon

the tendon at the back of the lower leg that connects the calf muscle to the heel bone

Acid base balance

the mechanisms that the body uses to keep its fluids close to neutral (neither basic nor acidic) so that the body can function properly

Acid reflux

a disorder in which acid in the stomach comes up into the oesophagus, because the valve separating the stomach and oesophagus does not function properly


a condition marked by abnormally high acid levels in the blood, associated with some forms of diabetes, lung disease, and severe kidney disease. Measuring the pH of blood is a way of finding out how acidic or alkaline the blood is. Acidosis or alkalosis can be an acute condition (develops quickly) or it may be a long-term chronic condition.


a skin condition characterised by inflamed, pus-filled areas that occur on the skin's surface, most commonly occurring during adolescence


a word describing any condition that is not present at birth, but develops some time during life

Acquired immunodeficiency syndrome

infection by the human immunodeficiency virus (HIV), which causes a weakening of the immune system


describes a condition or illness that begins suddenly and is usually short-lasting

Acute respiratory disease

an urgent condition in which oxygen levels in the blood are lower than normal and breathing is difficult


dependence on a substance (such as alcohol or other drugs) or an activity, to the point that stopping is very difficult and causes severe physical and mental reactions


infection and inflammation of a gland, especially a lymph node

Adipose tissue

another term for fatty tissue; it stores energy, insulates, and cushions the body

Adjuvant therapy

the use of drugs or radiation therapy in the treatment of cancer along with surgery

Adrenal failure

a condition in which the adrenal glands do not produce enough of the hormones that control important functions such as blood pressure

Adrenal glands

two small glands located on top of the kidneys that secrete several important hormones into the blood

Adverse reaction

an unintended and unwanted side effect of some sort of treatment, usually drug therapy

Aerobic exercise

physical activity during which the heart and lungs must work harder to meet the body's increased oxygen demand

Affective disorder

a mental disorder involving abnormal moods and emotions; affective disorders include manic-depressive disorder


the placenta and membranes that are eliminated from the woman's uterus following the birth of a child


normal contractions of the uterus after childbirth that usually occur for the first few days after delivery


see Acquired immunodeficiency syndrome

AIDS-related complex

symptoms including weight loss, fever, and enlarged lymph nodes experienced by people who are infected with HIV but do not yet have AIDS

Air embolism

the blockage of an artery by air bubbles, which may have entered during surgery or after an injury

Airway obstruction

blockage of the passage of air through the windpipe to the lungs


the passageways that air moves through while travelling in and out of the lungs during breathing


a condition in which people are born with insufficient amounts of the pigment melanin, which is responsible for hair, skin, and eye colour

Alcoholic cardiomyopathy

heart damage and failure caused by intake of too much alcohol

Alimentary canal

another term for the digestive tract


dangerously decreased acidity of the blood, which can be caused by high altitudes, hyperventilation, and excessive vomiting

Alkylating agents

substances used in cancer treatment that interfere with the division of cells


An allergen is a substance that causes an allergic reaction. There is a wide range of allergens from foods (such as peanuts and shellfish) to dog and cat hair, to plants and pollen.

Allergic rhinitis

irritation of the nasal passages and the whites of the eyes, causing sneezing, runny nose, and sore eyes


An allergy is an exaggerated response produced by the body, often to a common or frequently encountered allergen (or stimulus). It is a normal physiological response but magnified several fold in some people.


baldness or loss of hair, mainly on the head, either in defined patches or completely; the cause is unknown


see Amyotrophic lateral sclerosis

Altitude sickness

headaches, dizziness, and nausea usually experienced at heights above 8,000 ft because of reduced oxygen in the air

Alzheimer disease

a condition that occurs late in life and worsens with time in which brain cells degenerate; it is accompanied by memory loss, physical decline, and confusion


absence of menstrual periods, occurring either after or before menstruation has begun


a procedure in which a small amount of amniotic fluid is removed from the mother's womb in order to detect abnormalities of the foetus

Amniotic fluid

clear fluid that surrounds a foetus during pregnancy and cushions and protects it

Amyotrophic lateral sclerosis

the most common of a group of disorders known as motor neurone diseases, in which the nerves in the brain that control the movement of muscles degenerate and muscle function is gradually lost; commonly called Lou Gehrig's disease

Anabolic steroid

a drug similar to the male hormone testosterone that builds muscles and strengthens bones, but has adverse side effects


a condition in which the blood does not contain enough haemoglobin, the compound that carries oxygen from the lungs to other parts of the body


a loss of sensation in a certain part of the body or throughout the body


a substance that temporarily causes a person to be unable to feel pain, either in a certain area or over the entire body

Anal fissure

a long, open sore on the skin of the anus

Anal fistula

an abnormal tube-like passage connecting the anus to the surface of the surrounding skin

Anal sphincter

a ring of muscle fibres at the opening of the rectum, controlling the opening and closing of the anus


a drug that relieves pain, such as aspirin or acetaminophen

Anaphylactic shock

a life-threatening allergic reaction resulting in difficulty breathing and low blood pressure


the structure of bodies; commonly refers to the study of body structure


a hormone (such as testosterone) that causes development of male characteristics and sex organs


a fatal birth defect in which the brain and spinal cord have failed to develop, resulting in the absence of a portion of the skull and brain


an abnormal swelling of the wall of an artery, caused by a weakening in the vessel wall

Angina pectoris

pain experienced in the chest, arms, or jaw because of a lack of oxygen to the heart muscle


a tumour made of blood vessels or lymph vessels that is not cancerous


the use of surgery to make a damaged blood vessel function properly again; may involve widening or reconstructing the blood vessel

Anorexia nervosa

a dangerous eating disorder mainly affecting young girls in which the sufferer has an intense fear of looking fat, avoids food, and loses weight excessively


a drug that neutralises stomach acids; used to treat indigestion, heartburn, and acid reflux

Antibiotic resistance

the development by bacteria of the ability to live in the presence of a certain antibiotic, making treatment difficult


bacteria-killing substances that are used to fight infection


a protein made by white blood cells that reacts with a specific foreign protein as part of the immune response


drugs used to stop abnormal blood clotting, such as to prevent stroke


drugs used to treat nausea and vomiting


a drug that relieves an allergic reaction by stopping the effects of histamine, the substance responsible for the negative symptoms associated with the reaction


drugs used to relieve the symptoms and prevent the damage that can occur from high blood pressure


substances that protect against cell damage by guarding the cell from oxygen free radicals


drugs used to treat severe mental disorders


chemicals applied to the skin that prevent infection by killing bacteria and other harmful organisms


the opening through which faeces are passed from the body


the main artery in the body, carrying oxygenated blood from the heart to other arteries in the body

Aortic stenosis

narrowing of the opening of the aortic valve in the heart, which increases resistance to blood flow from the left ventricle to the aorta; commonly a birth defect or caused by scarring and calcium accumulation in the valve from rheumatic fever

Apgar score

a system for evaluating the health of a new-born baby; rated on a scale of 0-10


the complete or partial failure of any organ or tissue to grow

Aplastic anaemia

a severely reduced number of red blood cells, white blood cells, and platelets


a possibly life-threatening condition in which breathing stops, for either a short or long period of time


surgical removal of the appendix to treat appendicitis


inflammation of the appendix


a short, tube-like structure that branches off the large intestine; does not have any known function


see AIDS-related complex


a disorder causing thickening and hardening of artery walls


inflammation of the walls of an artery that causes the passageway to become narrower; can lead to tissue damage because oxygen is not properly supplied


a large blood vessel that carries blood from the heart to tissues and organs in the body


a disease of the joints characterised by inflammation, pain, stiffness, and redness


a procedure used to examine the inside of a joint using a viewing tube (an endoscope)

Artificial insemination

injection of semen into the cervix

Artificial respiration/ventilation

the forcing of air (either by mouth-to-mouth or mouth-to-nose means) into the lungs of a person who has stopped breathing


excess fluid in the abdominal cavity, which leads to swelling

Ascorbic acid

the chemical term for vitamin C


the failure either to produce or to ejaculate sperm


the medical term for suffocation; can be caused by choking on an object, by lack of oxygen in the air, or by chemicals such as carbon monoxide, which reduce the amount of oxygen in the blood


a disorder characterised by inflamed airways and difficulty breathing


a disorder in which the front surface of the eye (the cornea) is not correctly spherical, resulting in blurry vision


a procedure performed to remove plaque that is blocking an artery


fatty deposits on the inner walls of blood vessels, which can cause narrowing and decrease blood flow


narrowing of the lining of the arteries due to the accumulation of fat and other materials; leads to coronary heart disease, stroke, and other disorders

Athlete's foot

an infection between the toes caused by a fungus, which leads to sore, cracked, and peeling skin


a birth defect in which a normal body opening or canal is absent; usually requires surgical repair soon after birth


the two upper chambers of the heart; the singular form is atrium

Atrial fibrillation

an irregular heartbeat in which the upper chambers of the heart (the atria) beat inconsistently and rapidly

Atrial flutter

an irregular heartbeat in which the upper chambers of the heart (the atria) beat rapidly but consistently

Atrial septal defect

a hole located in the wall between the two upper chambers of the heart


the shrinkage or near disappearance of a tissue or organ

Attention-deficit disorder

a disorder mainly present in children and adolescents, characterised by learning and behaviour problems, inability to pay attention, and sometimes hyperactivity


a graph showing a person's hearing ability, determined from a set of tests examining hearing acuity of different sound frequencies


a "warning" signal that comes before a migraine headache or an epileptic seizure, which might include emotions or sensations of movement or discomfort


the act of listening to sounds within the body, such as the heartbeat, with a stethoscope


a mental disorder characterised by an inability to relate to other people and extreme withdrawal

Autoimmune disease

Autoimmune disease occurs when an individual's immune system begins attacking their own cells. Autoimmune diseases include rheumatoid arthritis, lupus, psoriasis, pernicious anaemia, multiple sclerosis as well as thyroid disorders Hashimoto's thyroiditis and Graves' disease.

Autonomic nervous system

the part of the nervous system that controls automatic body functions, such as heart rate, sweating, pupil dilation, and digestion; divided into the sympathetic nervous system and the parasympathetic nervous system


the examination of a body following death, possibly to determine the cause of death or for research

Autosomal dominant

a term describing a gene on any chromosome other than the sex chromosomes that produces its effect whenever it is present; can also describe the effect of the gene itself

Autosomal recessive

a term used to describe a gene on any chromosome other than the sex chromosomes that produces its effect only when two copies of it are present; can also describe the effect of the gene itself


medical term for the armpit

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