a small electronic device that is surgically implanted to stimulate the heart muscle to provide a normal heartbeat

Paget's disease

a disorder occurring in the middle-aged and elderly in which bone does not form properly, causing bone weakening, thickening, and deformity


the roof of the mouth

Palliative treatment

treatment that relieves the symptoms of a disorder without curing it


abnormally pale skin; usually refers to the skin of the face


the use of the hands to feel parts of the body to check for any abnormalities


an abnormally rapid and strong heartbeat


loss of sensation or ability to move


a long gland located behind the stomach that produces enzymes that help to break down food and hormones (insulin and glucagon) that help to regulate glucose levels in the blood


inflammation of the pancreas, which is often caused by alcohol abuse


a widespread epidemic

Panic disorder

an emotional disorder characterised by attacks of anxiety that have no normal causes; usually made worse by stress

Pap smear

a test in which cells are scraped off the cervix and examined for abnormalities; used to detect changes that might precede cervical cancer and to diagnose viral infections such as herpes simplex


a tumour occurring on the skin or mucous membranes; usually not cancerous


the insertion of a needle into a body cavity to relieve pressure, inject a drug, or remove a sample for analysis


the inability to use a muscle because of injury to or disease of the nerves leading to the muscle


a person trained to give first aid and other emergency medical care


a disorder in which a person becomes overly suspicious and emotionally sensitive


strangulation of the head of the penis by a tight or inflamed foreskin that has been pulled back


complete or partial loss of sensation and movement of the legs


an organisms that lives on or in other organisms, from which it obtains nutrients

Parasympathetic nervous system

the part of the autonomic nervous system that is stimulated during times of relaxation

Parathyroid glands

small glands located in the neck that produce a hormone that regulates the levels of calcium in the blood

Parathyroid hormone

a hormone released by the parathyroid glands that plays a role in controlling calcium levels in the blood


the surgical removal of one or more of the parathyroid glands


the introduction of a substance into the body by any route other than the digestive tract, such as through a vein or muscle


partial paralysis


numbness or tingling in the skin; commonly referred to as "pins and needles"

Parkinson's disease

a brain disorder in which there is a lack of the chemical messenger dopamine, which helps control muscle movement; leads to muscle stiffness, weakness, and trembling


a bacterial or yeast infection of the skin around the nail

Parotid glands

salivary glands located in the mouth near the ears


a sudden attack or worsening of a disease's symptoms

Partial mastectomy

a treatment for breast cancer in which a tumour is removed, along with the skin covering it and some of the surrounding tissues and muscles

Partial seizure

an abnormal electrical discharge in a certain area of the brain, affecting only certain functions

Passive exercise

exercise of an injured part of the body involving no effort from that injured part

Passive smoking

a non-smoker inhaling the cigar, cigarette, or pipe smoke of others (called second-hand smoke) in the same area, which increases the non-smoker's risk of cancer and respiratory disorders


the medical term for the kneecap


not obstructed; open

Patent ductus arteriosus

a genetic disorder of the heart in which a channel connecting the pulmonary artery and the aorta fails to close and the heart must work harder to supply the body with blood

Paternity testing

use of blood tests to match up DNA or specific blood proteins to determine whether a man is the father of a child


any substance capable of causing a disease; usually refers to a disease-causing micro-organism


the production and development of a disease or disorder


the study of disease

Patient-controlled analgesia

a system for administering pain-killing drugs in which the amount of drug delivered is controlled by the patient

Peak flow measurement

the maximum speed that air is exhaled from the lungs; used to diagnose asthma or to determine the effectiveness of asthma medications

Pectoral muscles

the muscles of the upper part of the chest that move the arm across the body, raise some of the ribs, and move the shoulders


a deficiency of the vitamin niacin; causes dermatitis, diarrhoea, and mental disorders

Pelvic examination

an examination of a woman's reproductive organs

Pelvic inflammatory disease

inflammation of a woman's internal reproductive organs, usually as a result of a bacterial infection; one of the most common causes of pelvic pain and infertility in women


the group of bones in the lower part of the trunk that support the upper body and protect the abdominal organs

Penile function tests

tests used to determine the cause of impotence, including blood tests and nerve function tests

Penile implant

an inflatable device surgically inserted into the penis that allows a man with impotence to have sexual intercourse


the external male reproductive organ, which passes urine and semen out of the body


the enzyme found in gastric juice that helps digest protein

Peptic ulcer

an erosion in the lining of the oesophagus, stomach, or small intestine, usually caused in part by the corrosive action of gastric acid


a procedure that is performed through the skin, such as an injection


a hole in an organ or body structure caused by disease or injury

Periarteritis nodosa

inflammation and weakening of small and medium arteries

Pericardial effusion

fluid build-up inside of the pericardium, affecting the performance of the heart


inflammation of the membranous sac that covers the heart, causing chest pain and fever


the membranous sac that covers the heart and the base of the blood vessels that are attached to the heart


occurring just before or just after birth


the tissue covering bones, except the surfaces in joints


inflammation of the periosteum

Peripheral nervous system

the nerves that branch out from the brain and spinal cord to the rest of the body

Peripheral vascular disease

the narrowing of blood vessels in the legs or arms, causing pain and possibly tissue death (gangrene) as a result of a reduced flow of blood to areas supplied by the narrowed vessels


wavelike movement of smooth muscle-containing tubes, such as the digestive tract


the membrane that lines the abdominal cavity and covers the abdominal organs


inflammation of the peritoneum

Pernicious anaemia

Pernicious anaemia is an autoimmune disease in which the body's immune system attacks cells in the stomach leaving it unable to absorb vitamin B12. Vitamin B12 is essential for the production of normal red blood cells. Symptoms include excessive tiredness, numbness in the arms and legs, weakness and unsteadiness.

Perthes' disease

inflammation of the growing head of a femur; a type of osteochondritis juvenilis


a bacterial infection of the respiratory tract characterised by short, convulsive coughs that end in a whoop sound when breath is inhaled (commonly called whooping cough); mainly affects children

PET scanning

see Positron emission tomography scanning

Petit mal

a seizure characterised by loss of awareness for brief periods

Peutz-Jeghers syndrome

a genetic disorder in which there are polyps in the small intestine and brown melanin spots on the lips, mouth, fingers, and toes


a measure of the acidic or basic character of a substance


an immune system cell that can surround and digest foreign bodies, unwanted cellular material, and micro-organisms

Phantom limb

the sensation of a limb after it has been amputated


the study of medications, including drug development


inflammation of the throat (the pharynx), causing sore throat, fever, earache, and swollen glands


the throat; the tube connecting the back of the mouth and nose to the oesophagus and windpipe


a group of drugs used as antipsychotics, antihistamines, and antiemetics


a hereditary disorder in which the enzyme that converts the amino acid phenylalanine into another amino acid is defective, meaning phenylalanine must be kept out of the diet


a noncancerous tumour of cells that produce epinephrine and norepinephrine, causing higher levels of these hormones in the blood and an increase in blood pressure


tightness of the foreskin, which prevents it from being moved back over the head of the penis


inflammation of a vein


formation of a blood clot in a vein


mucus and other material produced by the lining of the respiratory tract; also called sputum


a persisting fear of and desire to avoid something


salts containing phosphorus; essential to some body functions such as the bones and teeth


fatty substances that make up the membranes surrounding cells


a mineral that is an important part of structures such as bones, teeth, and membranes in the body; also involved in numerous other chemical reactions


tissue destruction using a focused beam of light


an abnormal sensitivity of the eyes to light


an abnormal reaction to sunlight, which usually occurs as a rash


treatment with some form of light

Physical therapy

the treatment of injuries or disorders using physical methods, such as exercise, massage, or the application of heat


the study of the body's functions


chemicals in plants that might help protect against disorders such as cancer


a desire to eat materials that are not food

Pickwickian syndrome

extreme obesity along with shallow breathing, sleep apnoea, excessive sleepiness, and heart failure


see Pelvic inflammatory disease


the coloration of the skin, hair, and eyes by the pigment melanin


inflammation of the membrane that covers the white of the eyes and lines the eyelids, causing redness, discomfort, and a discharge; can be caused by infection or allergies


a small parasite worm that can live in the intestines; commonly affects children

Pituitary adenoma

a noncancerous tumour of the pituitary gland

Pituitary gland

The pituitary gland is a small, round gland located at the base of the brain that releases hormones that control other glands (such as the thyroid) in the body.

Pityriasis alba

a common childhood or adolescent disorder in which there are pale, scaly patches on the skin of the face

Pityriasis rosea

a mild skin condition in which flat, scaly spots occur on the trunk and upper arms

Pivot joint

a joint designed for rotational movement


see Phenylketonuria


a chemically inactive substance given in place of a drug to test how much of a drug's effectiveness can be attributed to a patient's expectations that the drug will have a positive effect

Placebo effect

the positive or negative response to a drug that is caused by a person's expectations of a drug rather than the drug itself


an organ formed in the uterus during pregnancy that links the blood of the mother to the blood of the foetus; provides the foetus with nutrients and removes waste

Placenta praevia

a disorder in which the placenta develops at the lower section of the uterus (close to or covering the cervix); varies in severity, from no effect on a pregnancy to vaginal bleeding and danger to the mother and the foetus

Placental abruption

the separation of the placenta from the wall of the uterus before childbirth, which causes severe bleeding that threatens the life of the mother and the foetus

Placental insufficiency

a disorder occurring during pregnancy in which the placenta does not function properly, causing the foetus to be deprived of nutrients


a serious infectious disease transmitted to humans through bites of rodent fleas

Plantar reflex

the normal curling of the toes downward when the sole of the foot is stroked

Plantar wart

a rough-surfaced, hard spot on the sole of the foot that is caused by a virus


an area of build-up of fat deposits in an artery, causing narrowing of the artery and possibly heart disease; dental plaque refers to a coating on the teeth, consisting of saliva, bacteria, and food debris, which causes tooth decay


the liquid part of the blood, containing substances such as nutrients, salts, and proteins

Plasma cell

a white blood cell that makes antibodies


a procedure for removing unwanted substances from the blood in which blood is drawn, its plasma is separated and replaced, and the cleansed blood is returned to the body


the smallest particle found in the blood, which plays a major role in forming blood clots


the double-layered membrane that lines the lungs and chest cavity and allows for lung movement during breathing

Pleural effusion

a build-up of fluid between the membranes that line the lungs and chest cavity (the pleura); causes compression of the lungs, which leads to breathing difficulty

Pleural membranes

the pleura

Pleural rub

a rubbing sound produced by inflamed pleural membranes that can be heard when breathing

Pleural space

the space between the two layers of the pleura


inflammation of the lining of the lungs and chest cavity, usually caused by a lung infection; characterised by sharp chest pain


pain in the chest caused by a virus

Plummer-Vinson syndrome

difficulty swallowing due to an abnormal web of tissue across the upper part of the oesophagus


see Pre-menstrual syndrome


a respiratory disease caused by dust inhalation

Pneumocystis pneumonia

an opportunistic infection of the lungs caused by a single-celled parasite


surgical removal of a lung


inflammation of the lungs due to a bacterial or viral infection, which causes fever, shortness of breath, and the coughing up of phlegm


a condition in which air enters the space between the chest wall and the lungs, causing chest pain and shortness of breath; may occur spontaneously or be the result of a disease or an accident


an infectious disease caused by a virus; usually causes only mild symptoms but in rare cases can attack the brain and spinal cord and cause paralysis or death


arthritis occurring in more than one joint

Polycystic kidney disease

a condition in which there are multiple, slow-growing cysts on both kidneys

Polycystic ovary syndrome

a hereditary disease characterised by multiple cysts on the ovaries, obesity, excessive hairiness, infertility, and irregular menstruation


an increased amount of red blood cells in the blood


the presence of an excessive number of fingers or toes


excessive thirst

Polymyalgia rheumatica

a rare disease of the elderly, characterised by muscle stiffness and pain in the hips, thighs, shoulders, and neck


an autoimmune disease of connective tissue in which muscles weaken and become inflamed


a growth that occurs on mucous membranes such as those in the nose and intestine; bleeds easily and can become cancerous


a complex carbohydrate composed of three or more simple carbohydrate molecules joined together

Polyunsaturated fat

a fat or oil that contains well below the maximum number of hydrogen atoms possible; thought to reduce the risk of coronary heart disease


the excessive production of urine; can be a symptom of various diseases, most notably diabetes mellitus


a group of genetic disorders in which substances called porphyrins build up in the blood, often causing rashes brought on by exposure to sunlight and reactions to certain drugs

Portal hypertension

increased blood pressure in the portal vein

Portal vein

the vein connecting the stomach, intestines, and spleen to the liver

Positron emission tomography scanning

an imaging method in which substances emitting positrons (positively charged particles) are introduced into the body, and detectors connected to a computer are used to form images of the tissues

Post-mortem examination

examination of a body after death to determine the cause of death; commonly called an autopsy

Post-traumatic stress disorder

feelings of anxiety experienced after a particularly frightening or stressful event, which include recurring dreams, difficulty sleeping, and a feeling of isolation

Postcoital contraception

the prevention of pregnancy after sexual intercourse has occurred


describes something that is located in or relates to the back of the body

Postmenopausal bleeding

bleeding from the vagina that occurs after menopause

Postmyocardial infarction syndrome

a condition that occurs following a heart attack or heart surgery; characterised by fever, chest pain, pericarditis, and pleurisy


describes something that occurs after birth, usually to the baby


a term that describes something that occurs after childbirth, usually to the mother

Postural drainage

drainage of mucus from specific areas of the lungs by placing the body in a specific position

Postural hypotension

unusually low blood pressure that occurs after suddenly standing or sitting up


a mineral that plays an important role in the body, helping to maintain water balance, normal heart rhythm, conduction of nerve impulses, and muscle contraction


a serious disorder that occurs in the second half of pregnancy, in which a woman experiences high blood pressure, fluid retention, nausea, and headaches; if not treated it can lead to eclampsia

Pre-menstrual syndrome

physical and emotional changes that occur in a woman 1 or 2 weeks before menstruation, at or after ovulation; characterised by irritability, tension, depression, and fatigue


describes a condition from which cancer is likely to develop

Precordial movement

movement of the heart that is seen and felt through the chest wall

Premature labour

labour that begins before the full term of pregnancy (about 37 weeks)

Premature rupture of membranes

the rupture of the sac that holds the fluid surrounding the foetus before the full term of pregnancy (about 37 weeks)


drugs, usually painkillers, taken 1 to 2 hours before surgery


a term that describes the period of a few years in a woman's life just before menopause

Prenatal care

medical care of a pregnant woman and the foetus

Prenatal diagnosis

techniques used to diagnose abnormalities in a foetus

Prenatal testing

tests performed on a pregnant woman or her foetus to prevent or diagnose abnormalities

Prepared childbirth

a technique in which a pregnant woman tries to minimise use of pain-relief medications during childbirth by learning relaxation techniques


the foreskin


the loss of hearing that occurs naturally with age


the loss of the ability to focus the eyes on near objects that occurs naturally with age, as a result of loss of elasticity of the lens of the eyes

Pressure point

specific points on the body where external pressure can be applied to prevent excessive arterial bleeding

Pressure sore

an ulcer (erosion) on the skin that is a result of being bedridden; commonly called a bedsore


a painful, persistent erection without sexual arousal, requiring emergency treatment

Prickly heat

a rash involving small, red, itchy spots and a prickly sensation that usually appears where sweat builds up


a disease that began in the affected location


an agent that is believed to cause several degenerative brain diseases


severe prolapse of an organ


pain in the rectum


inflammation of the rectum, which causes soreness and sometimes mucus and/or pus in the stool


examination of the rectum using a viewing instrument

Productive cough

a cough that brings up phlegm, which is the body's natural way of clearing blocked airways


an extremely rare condition in which the body ages prematurely


a female sex hormone that plays many important roles in reproduction, including the thickening of the lining of the uterus during the menstrual cycle; and during pregnancy, the functioning of the placenta, and the initiation of labour


a doctor's probable forecast of the effects and outcome of a disease

Progressive muscular atrophy

gradual degeneration and weakening of muscles due to a degenerative spinal cord


a hormone released by the pituitary gland that is responsible for the development of breasts and milk production in females


the displacement of an organ from its normal position to a new one

Prolapsed disk

see Disk prolapse


anything used to prevent disease


the body's system for determining its position relative to the outside world

Prostate gland

an organ located under the bladder that produces a large part of the semen


the partial or complete surgical removal of the prostate gland


symptoms caused by an enlarged prostate gland, including difficulty with urination


inflammation of the prostate gland, usually due to a bacterial infection spread from the urethra


an artificial replacement for a missing part of the body


large molecules made up of amino acids that play many major roles in the body, including forming the basis of body structures such as skin and hair, and important chemicals such as enzymes and hormones

Prothrombin time

the time it takes for a sample of blood to clot after substances that speed clotting time have been added; used to measure the effect of anticoagulants


a gene that is normally inactive but can become a cancer-causing oncogene if made active

Proton pump inhibitor

a drug used to treat peptic ulcers that reduces the amount of gastric acid produced


a simple, single-celled organism


located nearer to a central point of reference on the body, such as the trunk


the medical term for itching


a form of arthritis with symptoms similar to gout that results from the depositing of calcium salts in a joint

Pseudomembranous enterocolitis

severe inflammation of the colon as a result of antibiotic use by an immunocompromised individual


a chlamydial infection resembling influenza that is spread to humans by the droppings of infected birds


drugs that contain chemicals derived from plants; used to treat the skin disorders psoriasis and vitiligo


a skin disorder characterised by patches of thick, red skin often covered by silvery scales

Psoriatic arthritis

a form of arthritis that develops as a complication of the skin disorder psoriasis


resulting from psychological or emotional disorders


relating to the mind and the processes of the mind


a mental disorder in which a serious inability to think, perceive, and judge clearly causes loss of touch with reality


describes a physical condition that is influenced by psychological or emotional factors


the treatment of mental and emotional disorders using psychological methods, such as counselling, instead of physical means


relating to psychosis

Psychotropic drug

a drug that has a psychological effect


the drooping of the upper eyelid


the period of time (usually between the ages of 10 and 15) during which sexual development occurs, allowing reproduction to become possible

Pubic louse

a small insect that lives in pubic hair, feeds on blood, and is usually spread by sexual contact; pubic lice are popularly called "crabs"

Pudendal block

a local anaesthesia procedure used during childbirth, causing the lower part of the vagina to be insensitive to pain


the external genitals, usually referring to the female

Puerperal sepsis

infection of the female genital tract following childbirth, abortion, or miscarriage


the time period after childbirth (about 6 weeks) during which a woman's body returns to its normal physical state

Pulmonary artery

the artery that supplies the lungs with blood from the heart

Pulmonary embolism

blockage of the pulmonary artery by a floating mass in the blood

Pulmonary fibrosis

a condition in which the tissue of the lungs has become thick and scarred, usually because of inflammation caused by lung conditions such as pneumonia or tuberculosis

Pulmonary heart valve

the heart valve that stops blood pumped to the lungs from leaking back into the heart

Pulmonary hypertension

increased blood pressure in the arteries supplying blood to the lungs; caused by increased resistance to blood flow in the lungs, usually a result of a lung disease

Pulmonary insufficiency

a rare defect in the pulmonary heart valve in which it fails to close properly after each muscle contraction, allowing blood to leak back into the heart; weakens the heart's pumping ability

Pulmonary oedema

the build-up of fluid in lung tissue, which is usually caused by heart failure

Pulmonary stenosis

obstruction of the flow of blood from the heart to the lungs


the soft tissue inside of a tooth that contains blood vessels and nerves


the expansion and contraction of a blood vessel due to the blood pumped through it; determined as the number of expansions per minute


the opening at the centre of the iris in the eye that constricts (contracts) and dilates (widens) in response to light

Purpuric rash

areas of purple or reddish-brown spots on the skin, which are caused by bleeding from underlying tissues


a thick, yellowish or greenish fluid that contains dead white blood cells, tissues, and bacteria; occurs at the site of a bacterial infection


a small blister containing pus


a form of phototherapy that combines the use of psoralens and ultraviolet light to treat skin disorders


surgical removal of a kidney stone


inflammation of the kidney, usually due to a bacterial infection

Pyloric sphincter

a circular muscle located at the junction of the stomach and small intestine that controls the passage of food into the small intestine

Pyloric stenosis

narrowing of the outlet located at the junction of the stomach and small intestine


surgical widening of the outlet between the stomach and small intestine


a body temperature of above 98.6°F in the mouth or 99.8°F in the rectum


any substance that causes a fever


the presence of white blood cells in the urine; usually an indication of kidney or urinary tract infection

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