B cell

a white blood cell that makes antibodies to fight infections caused by foreign proteins

B lymphocyte

a type of white blood cell that makes antibodies and is an important part of the immune response


any bacteria that is rod-shaped; responsible for diphtheria, dysentery, tetanus, and tuberculosis, as well as other diseases


a condition in which bacteria are present in the bloodstream; may occur after minor surgery or infection and may be dangerous for people with a weakened immune system or abnormal heart valves


term used to describe a substance that stops the growth of bacteria (such as an antibiotic)


a tiny, single-celled micro-organism, commonly known as a germ; some bacteria, called pathogens, cause disease


bacteria in the urine; large amounts can indicate bladder, urethra, or kidney infection

Ball-and-socket joint

a joint consisting of a ball-shaped bone that fits into a cup-shaped bone, making the joint free to rotate; examples include the hip and shoulder

Balloon angioplasty

a technique that uses a balloon catheter to open arteries clogged with fatty deposits

Balloon catheter

a hollow tube with a small, inflatable balloon at the tip; used to open a narrowed artery or organ that has become blocked


a group of sedatives that reduce activity in the brain; are habit-forming and are possibly fatal when taken with alcohol

Barium enema

a technique in which barium is placed into the large intestine and rectum and then X-rays are taken to check for possible disorders of these organs

Barrier method of contraception

a birth-control technique using a condom, diaphragm, or another similar device to block the path of sperm to an egg

Bartholin's glands

two pea-sized glands that, when sexually aroused, release a fluid that lubricates the vagina

Basal cell carcinoma

a type of skin cancer that is caused by exposure to large amounts of sunlight; commonly found on the neck, face, and arms

Basal metabolic rate

the lowest rate at which a person can possibly use energy and remain alive; at this rate, only absolutely necessary functions such as breathing are maintained

BCG vaccine

a vaccine used to protect against tuberculosis

Becker's muscular dystrophy

a hereditary disease in which the muscles weaken and waste away; similar to Duchenne muscular dystrophy but starts later in life and advances more slowly

Bell's palsy

another name for facial palsy, the usually one-sided, temporary numbing of the facial muscles, caused by an inflamed nerve


see Decompression sickness

Benign tumour

a tumour that is not cancerous, which means it does not spread through the body, but may grow and become dangerous

Beta blocker

a type of drug used to treat high blood pressure and heart disorders by reducing the strength and rate of the pumping by the heart

Beta carotene

a pigment found in orange vegetables and fruits, which the body converts to vitamin A; possibly protects against cancer


a lens that corrects both near and distant vision by having two parts with different focusing strengths


a term describing a condition that affects both sides of the body or two paired organs, such as bilateral deafness (deafness in both ears)


a yellow-green liquid produced in the liver whose function is to remove waste from the liver and break down fats as food is digested

Bile duct

a tube that carries bile from the liver to the gallbladder and then to the small intestine

Biliary atresia

a birth defect in which the bile ducts are not completely developed; often a liver transplant is necessary

Biliary colic

a severe pain in the upper right section of the abdomen, usually caused by a gallstone passing out of the bladder or through the bile ducts

Biliary tract

the system of organs and ducts through which bile is made and transported from the liver to the small intestine


the orange-yellow pigment in bile, causing jaundice if it builds up in the blood and skin; the levels of bilirubin in the blood are used to diagnose liver disease

Binging and purging

behaviour characteristic of the disorder bulimia in which a person overeats then rids themselves of the food before it can be absorbed by the body, either by forced vomiting or through the use of laxatives


the science that studies the chemistry of living organisms, including humans


a drug that has the same effect on the body as another drug


a technique used to gain control over a function that is normally automatic (such as blood pressure or pulse rate); the function is monitored and relaxation techniques are used to change it to a desired level

Bipolar disorder

an illness in which the patient goes back and forth between opposite extremes; the most notable bipolar disorder is manic-depressive disorder, which is characterised by extreme highs and lows in mood

Birth canal

the passage that includes the uterus and vagina through which the baby passes at birth

Birth control

the regulation of the number of children born, referring either to the prevention of pregnancy (by birth control pill, sterilisation, etc) or the prevention of birth (by abortion, etc)

Birth defect

an abnormality that is present when a baby is born


any area of discoloured skin that is present when a baby is born


sexual interest in members of both sexes


an organ located in the pelvis whose function is to collect and store urine until it is expelled


inflammation of the eyelids

Blind spot

a spot in the field of vision that is not sensitive to light; it is a product of the entrance of the optic nerve into the eyeball, where no light receptors are present on the retina

Blood clot

a semisolid mass of blood that forms to help seal and prevent bleeding from a damaged vessel

Blood poisoning

see Septicaemia

Blood pressure

the tension in the main arteries that is created by the beating of the heart and the resistance to flow and elasticity of the blood vessels

Blood transfusion

the transfer of blood or any of its parts to a person who has lost blood due to an injury, disease, or operation

Blood type

a category used to describe a person's blood according to the kinds of proteins present on the surface of the red blood cells

Blood-brain barrier

a layer of tightly bound cells that prevents certain substances carried in the bloodstream from entering the brain


an inflamed, raised area of skin that is pus-filled; usually an infected hair follicle

Bone marrow

the fatty yellow or red tissue inside bones that is responsible for producing blood cells

Bone marrow transplant

a surgical procedure in which defective or cancerous bone marrow is replaced with healthy marrow, either from the patient or a donor

Bone spur

an abnormal growth of bone out of another bone, often located on the heel and usually painful


an additional dose of a vaccine taken after the first dose to maintain or renew the first one


poisoning from poorly preserved food contaminated with a dangerous bacterial toxin that results in paralysis


see Intestine


a slow heart rate, usually below 60 beats per minute in adults

Brain damage

permanent death or damage of brain cells resulting in decreased mental ability

Brain death

the condition in which the brain stops functioning while the heart continues to beat

Breech birth

childbirth in which the baby is turned around in the uterus and emerges head-last instead of head-first


an infection caused by a virus in the bronchioles (the smallest airways in the lungs), mainly affecting young children


inflammation of the bronchial tubes, which connect the trachea to the lungs


a substance that causes the lung airways to tighten up and become more narrow


a drug that widens the airways in the lungs to improve breathing; works by relieving muscle contraction or build-up of mucus


the temporary narrowing of the airways in the lungs, either as a result of muscle contraction or inflammation; may be caused by asthma, infection, lung disease, or an allergic reaction


see Contusion


an unaware clenching or grinding of the teeth, usually during sleep

Bubonic plague

a form of plague in which lymph nodes in the groin and armpit swell


a disorder in which a person eats large amounts of food then forces vomiting or uses laxatives to prevent weight gain (called binging and purging)


a hard, fluid-filled pad along the inside joint of the big toe; may be caused by wearing high-heeled shoes or a genetically weak joint

Burkitt's lymphoma

a cancer of lymph tissue that most frequently occurs in the abdomen, the ovaries, and the bones of the face; it is associated with malaria


a fluid-filled sac that cushions and reduces friction in certain parts of the body


inflammation of a bursa due to excessive pressure or friction, or from injury

Butterfly bandage

a butterfly-shaped bandage that can help close a minor cut for proper healing


a surgical technique in which the flow of blood or another body fluid is redirected around a blockage

This website uses cookies to ensure you get the best experience. Read more