Medical Glossary Index:

P

Pacemaker- 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

Palate- the roof of the mouth

Palliative treatment- treatment that relieves the symptoms of a disorder without curing it

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

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

Palpitation- an abnormally rapid and strong heartbeat

Palsy- loss of sensation or ability to move

Pancreas- 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

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

Pandemic- a widespread epidemic

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

Papilloma- a tumor occurring on the skin or mucous membranes; usually not cancerous

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

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

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

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

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

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

Paraplegia- complete or partial loss of sensation and movement of the legs

Parasite- 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

Parathyroidectomy- the surgical removal of one or more of the parathyroid glands

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

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

Paresis- partial paralysis

Paresthesia- 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

Paronychia- a bacterial or yeast infection of the skin around the nail

Parotid glands- salivary glands located in the mouth near the ears

Paroxysm- a sudden attack or worsening of a disease's symptoms

Partial mastectomy- a treatment for breast cancer in which a tumor 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 nonsmoker inhaling the cigar, cigarette, or pipe smoke of others (called second-hand smoke) in the same area, which increases the nonsmoker's risk of cancer and respiratory disorders

Patella- the medical term for the kneecap

Patent- 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

Pathogen- any substance capable of causing a disease; usually refers to a
disease-causing microorganism

Pathogenesis- the production and development of a disease or disorder

Pathology- 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

Pellagra- a deficiency of the vitamin niacin; causes dermatitis, diarrhea, 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

Pelvis- 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

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

Pepsin- the enzyme found in gastric juice that helps digest protein

Peptic ulcer- an erosion in the lining of the esophagus, stomach, or small
intestine, usually caused in part by the corrosive action of gastric acid

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

Perforation- 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 buildup inside of the pericardium, affecting the performance of the heart

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

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

Perinatal- occurring just before or just after birth

Periosteum- the tissue covering bones, except the surfaces in joints

Periostitis- 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

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

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

Peritonitis- inflammation of the peritoneum

Pernicious anemia- an anemia caused by a failure to absorb vitamin B12; which is essential in the production of normal red blood cells

Perthes' disease- inflammation of the growing head of a femur; a type of osteochondritis juvenilis

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

Petit mal- a seizure characterized by loss of awareness for brief periods

PET scanning- see Positron emission tomography scanning

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

pH- a measure of the acidic or basic character of a substance

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

Phantom limb- the sensation of a limb after it has been amputated

Pharmacology- the study of medications, including drug development

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

Pharynx- the throat; the tube connecting the back of the mouth and nose to the esophagus and windpipe

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

Phenylketonuria- 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

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

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

Phlebitis- inflammation of a vein

Phlebothrombosis- formation of a blood clot in a vein

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

Phobia- a persisting fear of and desire to avoid something

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

Phospholipids- fatty substances that make up the membranes surrounding cells

Phosphorus- 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

Photocoagulation- tissue destruction using a focused beam of light

Photophobia- an abnormal sensitivity of the eyes to light

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

Phototherapy- 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

Physiology- the study of the body’s functions

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

Pica- a desire to eat materials that are not food

Pickwickian syndrome- extreme obesity along with shallow breathing, sleep apnea, excessive sleepiness, and heart failure

PID- see Pelvic inflammatory disease

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

Pinkeye- 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

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

Pituitary adenoma- a noncancerous tumor of the pituitary gland

Pituitary gland- a small, round gland located at the base of the brain that
releases hormones that control other glands and body processes

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

PKU- see Phenylketonuria

Placebo- 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

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

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 fetus

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

Placenta previa- 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 fetus

Plague- 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

Plaque- an area of buildup 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

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

Plasma cell- a white blood cell that makes antibodies

Plasmapheresis- 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

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

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

Pleural effusion- a buildup 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

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

Pleurodynia- 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 esophagus

PMS- see Premenstrual syndrome

Pneumoconiosis- a respiratory disease caused by dust inhalation

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

Pneumonectomy- surgical removal of a lung

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

Pneumothorax- 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

Poliomyelitis- 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

Polyarthritis- 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 characterized by multiple
cysts on the ovaries, obesity, excessive hairiness, infertility, and irregular
menstruation

Polycythemia- an increased amount of red blood cells in the blood

Polydactyly- the presence of an excessive number of fingers or toes

Polydipsia- excessive thirst

Polymyalgia rheumatica- a rare disease of the elderly, characterized by muscle stiffness and pain in the hips, thighs, shoulders, and neck

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

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

Polysaccharide- 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

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

Porphyria- 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

Postcoital contraception- the prevention of pregnancy after sexual intercourse has occurred

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

Postmenopausal bleeding- bleeding from the vagina that occurs after
menopause

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

Postmyocardial infarction syndrome- a condition that occurs following a heart attack or heart surgery; characterized by fever, chest pain, pericarditis, and pleurisy

Postnatal- describes something that occurs after birth, usually to the baby

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

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

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

Potassium- 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

Precancerous- 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

Preeclampsia- 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

Premature labor- labor 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 fetus before the full term of pregnancy (about 37 weeks)

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

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

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

Prenatal care- medical care of a pregnant woman and the fetus

Prenatal diagnosis- techniques used to diagnose abnormalities in a fetus

Prenatal testing- tests performed on a pregnant woman or her fetus to prevent
or diagnose abnormalities

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

Prepuce- the foreskin

Presbycusis- the loss of hearing that occurs naturally with age

Presbyopia- 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

Priapism- 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

Primary- a disease that began in the affected location

Prion- an agent that is believed to cause several degenerative brain diseases

Procidentia- severe prolapse of an organ

Proctalgia- pain in the rectum

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

Proctoscopy- 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

Progeria- an extremely rare condition in which the body ages prematurely

Progesterone- 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 labor

Prognosis- 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

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

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

Prolapsed disk- see Disk prolapse

Prophylactic- anything used to prevent disease

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

Prostatectomy- the partial or complete surgical removal of the prostate gland

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

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

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

Prosthesis- an artificial replacement for a missing part of the body

Proteins- 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

Proton pump inhibitor- a drug used to treat peptic ulcers that reduces the
amount of gastric acid produced

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

Protozoan- a simple, single-celled organism

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

Pruritus- the medical term for itching

Pseudogout- 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

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

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

Psoriasis- a skin disorder characterized 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

Psychogenic- resulting from psychological or emotional disorders

Psychological- relating to the mind and the processes of the mind

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

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

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

Psychotic- relating to psychosis

Psychotropic drug- a drug that has a psychological effect

Ptosis- the drooping of the upper eyelid

Puberty- 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 anesthesia procedure used during childbirth, causing the lower part of the vagina to be insensitive to pain

Pudendum- the external genitals, usually referring to the female

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

Puerperium- 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 edema- the buildup of fluid in lung tissue, which is usually caused by heart failure

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

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

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

Pupil- the opening at the center 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

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

Pustule- a small blister containing pus

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

Pyelolithotomy- surgical removal of a kidney stone

Pyelonephritis- 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

Pyloroplasty- surgical widening of the outlet between the stomach and small intestine

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

Pyrogen- any substance that causes a fever

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