Pacemaker - an electronic device that is surgically implanted into the patient's chest to regulate heartbeat.
Pain - an unpleasant sensory or emotional experience primarily associated with tissue damage, or described in terms of tissue damage, or both.
Pain threshold - the least experience of pain that a person can recognize.
Pain tolerance level - the greatest level of pain that a person is prepared to tolerate.
Palliative treatment - therapy that relieves symptoms, such as pain, but does not alter the course of the disease. Its primary purpose is to improve the quality of life.
Pallidotomy - a surgical procedure in which a small amount of tissue in a part of the brain, called the globus pallidus, is destroyed in order to improve symptoms of tremor, rigidity, and bradykinesia associated with Parkinson's disease.
Palming - an imaging technique to promote relaxation involving the visualization of color.
Palpation - examination by feeling part of the body.
Palpitation - sensation of rapid heartbeats.
Palsy - paralysis of a muscle or group of muscles.
Pancreas - a long gland that lies behind the stomach, which manufactures insulin and digestive enzymes.
Pancreatitis - inflammation of the pancreas.
Panic disorder - a type of anxiety disorder characterized by chronic, repeated, and unexpected panic attacks - bouts of overwhelming fear of being in danger when there is no specific cause for the fear. In between panic attacks, persons with panic disorder worry excessively about when and where the next attack may occur.
Pap test (also called Pap smear) - a screening test that involves microscopic examination of cells collected from the cervix; used to detect changes that may be cancer or may lead to cancer, and to show noncancerous conditions, such as infection or inflammation.
Papillary stenosis - condition in which the openings of the bile ducts and pancreatic ducts narrow.
Paranoid personality disorder - a psychiatric condition in which an affected person is often cold, distant, and unable to form close, interpersonal relationships. Often overly, yet unjustifiably, suspicious of their surroundings, people with paranoid personality disorder generally cannot see their role in conflict situations and often project their feelings of paranoia as anger onto others.
Paraplegia - loss of movement and sensation in both legs.
Parenteral nutrition (also called hyperalimentation or total parenteral nutrition) - a liquid food mixture that is given directly into the veins through a special type of IV in the chest or arm called a central line. Parenteral nutrition is given in situations in which a person is unable to take in any or enough nutrition by mouth because of illness or injury.
Parietal cells - cells in the stomach wall that make hydrochloric acid.
Parkinsonism - the name given to a group of disorders with similar features, including tremor, rigidity, postural instability, and bradykinesia, resulting from the loss of dopamine-producing brain cells.
Parkinson's disease (PD) - a slowly progressing, degenerative disease that is usually associated with the following symptoms, all of which result from the loss of dopamine-producing brain cells: tremor or trembling of the arms, jaw, legs, and face; stiffness or rigidity of the limbs and trunk; bradykinesia (slowness of movement); postural instability, and/or impaired balance and coordination.
Paronychia - a skin infection around a finger or toenail.
Parosmia - any disease or perversion of the sense of smell, especially the subjective perception of odors that do not exist.
Partial (segmental) mastectomy - surgery to remove a cancerous breast tumor and a larger portion of the normal breast tissue around the tumor. The surgeon may also remove the lining over the chest muscles below the tumor and some of the lymph nodes under the arm.
Partial abdominoplasty - a "mini tummy tuck." This procedure is ideal for individuals who have fat deposits limited to the area below the navel.
Partial colectomy - the removal of part of the large intestine.
Partial nephrectomy - a surgical procedure in which only part of the kidney is removed, preserving as much of the kidney as possible.
Patch - a flat, discolored spot.
Patella - kneecap.
Patellar tendonitis - inflammatory condition of the patellar ligament, usually due to overuse.
Pathologist - physician who identifies diseases by studying cells and tissues under a microscope.
Pathology - the study of diseases.
Pauciarticular - a form of juvenile rheumatoid arthritis that affects four or fewer joints.
Peak flow meter (PFM) - a device used to measure the air flowing out of the lungs, called peak expiratory flow rate (PEFR). During an asthma attack or other respiratory flare up, the large airways in the lungs slowly begin to narrow. This will slow the speed of air leaving the lungs and can be measured by a PFM. This measurement is very important in evaluating how well or how poorly the disease is being controlled.
Prick skin test - a test to determine if a patient is allergic to certain substances. A drop of the substance being tested is placed on the patient's forearm or back and the skin is pricked with a needle, allowing a tiny amount to enter the skin. If the patient is allergic to the substance, a wheal (mosquito bite-like bump) will form at the site within about 15 minutes.
Peak flow monitoring - a measure of lung function.
Pediatric dentist - a specialist in the field of dentistry whose primary concern involves the oral healthcare of children, from infancy through the teenage years.
Pediatrics - the branch of medicine that deals with diagnosis, treatment, and prevention of diseases in children.
Pelvic examination - an internal examination of the uterus, vagina, ovaries, fallopian tubes, bladder, and rectum.
Pelvic inflammatory disease (PID) - inflammation of the pelvic organs caused by a type of bacteria.
Pelvic lymph node dissection - removal of some lymph nodes from the pelvis to determine the spread of prostate cancer in men or gynecologic cancers in women.
Pelvis - a basin-shaped structure that supports the spinal column and contains the sacrum, coccyx, and hip bones (ilium, pubis, and ischium).
Penis - the outer reproductive organ of a male.
Pepsin - enzyme made in the stomach that breaks down proteins.
Peptic - related to the stomach and the duodenum, where pepsin is present.
Peptic ulcer - an open sore in the lining of the esophagus, stomach, or duodenum; usually caused by the bacterium Helicobacter pylori. An ulcer in the stomach is a gastric ulcer. An ulcer in the duodenum is a duodenal ulcer.
Perception (hearing) - process of knowing or being aware of information through the ear.
Percutaneous transhepatic cholangiography - X-ray of the gallbladder and bile ducts; a dye is injected through the abdomen to make the organs show up on the X-ray.
Percutaneous transluminal coronary angioplasty (PTCA) - a technique used to treat heart disease and chest pain by inflating a tiny balloon in the coronary arteries to permit more blood flow into the heart.
Perforated ulcer - an ulcer that breaks through the wall of the stomach or duodenum and causes the stomach contents to leak into the abdominal cavity.
Perforation - hole in the wall of an organ.
Perfusion - flow.
Perianal - area around the anus.
Pericardiocentesis - a diagnostic procedure that uses a needle to draw fluid from the pericardium (the membrane that surrounds the heart).
Pericarditis - inflammation of the membrane that surrounds the heart.
Pericardium - the membrane that surrounds the heart.
Perilymph fistula - an abnormal opening between the middle ear and the inner ear because of a tear or defect in the membranes separating the two.
Perimenopause (also called climacteric) - the transition period of time before menopause, marked by a decreased production of estrogen and progesterone, irregular menstrual periods, and transitory psychological changes.
Perineal - related to the perineum.
Perineum - area between the anus and the sex organs.
Periodontal disease (also called gum disease or gingivitis) - serious bacterial infections that destroy the gums and the surrounding tissues of the mouth.
Periodontist - a specialist in the field of dentistry responsible for the care and prevention of gum-related diseases, guided bone regeneration, and dental implants.
Periosteum - fiber-like covering of the bones; beneath the hard outer shell of the periosteum, there are tunnels and canals through which blood and lymphatic vessels run to carry nourishment for the bone.
Peripheral stem cell transplantation - a process in which the stem cells (immature cells from which blood cells develop) are removed, treated with anticancer drugs, and frozen until they are returned to the patient.
Peristalsis - wavelike contractions that move food through the digestive tract.
Peritoneum - lining of the abdominal cavity.
Peritonitis - infection of the peritoneum.
Personal flotation device (PFD) - any type of item, such as a lifejacket or life vest, that keeps a person afloat in water. Only U.S. Coast Guard-approved PFDs should be used on boats.
Pertussis (also called whooping cough) - a bacterial infection of the respiratory system that mainly affects infants and young children; caused by a bacterium, pertussis is characterized by paroxysms of coughing that end with the characteristic whoop as air is inhaled. Pertussis caused thousands of deaths in the 1930s and 1940s, but with the advent of a vaccine, the rate of death has declined dramatically.
Pessary - rubber or plastic device that is inserted through the vagina to help hold the uterus in place in women who have prolapse of the uterus.
Petechia - tiny red dots under the skin that are the result of very small bleeds.
Peutz-Jeghers syndrome - an Inherited condition in which many polyps grow in the intestine.
Peyronie's disease (also called curvature of the penis) - a condition in which the penis develops an abnormal bend during erection because of fibrous scar tissue under the skin of the penis.
Pfeiffer syndrome - a genetic condition characterized by abnormalities of the skull, hands, and feet.
Phalen's test - a test for carpal tunnel syndrome in which the wrists are flexed downward for one minute.
Phantom pain - pain that occurs after an amputation, below the level of the amputated limb.
Pharynx - space behind the mouth that serves as a passage for food from the mouth to the esophagus and for air from the nose and mouth to the larynx.
Phlebotomy - a procedure that involves removing blood from the body.
Phobia - an uncontrollable, irrational, and persistent fear of a specific object, situation, or activity.
Phonology - study of speech sounds.
Photodynamic therapy - a type of cancer treatment that uses a certain type of light and a special chemical to kill cancer cells.
Photophobia - sensitivity to light.
Photorefractive keratectomy (PRK) - a surgical procedure using an excimer laser to change the shape of the cornea to correct certain refractive errors such as myopia (nearsightedness) or hyperopia (farsightedness).
Physiatrist - a physician who specializes in physical medicine and rehabilitation.
Physiatry - branch of medicine that deals with restoring function for a person who has been disabled as a result of a disease, disorder, or injury.
Pigmentosa, xerostoma - a rare, inherited, skin disease that causes the skin to become very sensitive to ultraviolet light.
Pinguecula - a condition in which a tiny yellow bump occurs over the white part of the eye, usually on the side of the eye nearer to the nose. The cause is unknown, but it appears to be associated with prolonged exposure to sunlight.
Pituitary gland - gland at the base of the brain that secretes hormones and regulates and controls other hormone-secreting glands and many body processes, including reproduction.
Pityriasis rosea - a common skin condition characterized by scaly, pink, and inflamed skin.
Placenta - organ that develops in the uterus during pregnancy; links the blood supplies of a pregnant woman to the fetus to provide nutrients and remove waste products.
Placenta previa - abnormal location of the placenta in the lower part of the uterus, near or over the cervix.
Placental abruption - premature detachment of the placenta from the wall of the uterus, causing severe bleeding that is life threatening to both a pregnant woman and fetus.
Plantar fascia - a long band of connecting tissue running from the heel to the ball of the foot.
Plantar warts - warts that occur on the sole of the foot and look like calluses; result from an infection or a specific virus.
Plaque - deposits of fat or other substances attached to the artery wall.
Plasma - the watery, liquid part of the blood in which the red blood cells, the white blood cells, and platelets are suspended.
Plastic surgery - the surgical specialty that deals with the reconstruction of facial and body tissue that requires a reshaping or remolding due to disease, a defect, or disorder - in order to approximate a normal appearance or to repair working ability.
Plateletpheresis - a procedure used to remove platelets from the blood.
Platelets - cells found in the blood that are needed to control bleeding; often used in the treatment of leukemia and other forms of cancer.
Pleura - membrane that covers the outside of the lung.
Pleural effusion - a collection of fluid between the lung and chest wall.
Pleurisy - inflamed membranes around the lungs.
Pluripotent stem cell - a type of stem cell that can develop into almost any type of body cell.
Pneumatic otoscope - an instrument that blows a puff of air into the ear to test eardrum movement.
Pneumoconiosis - a lung disease caused by the long-term breathing (ingestion) of dust.
Pneumonectomy - removal of an entire lung.
Pneumothorax (also called collapsed lung) - a condition in which air becomes trapped in the pleural space (the area between the lung and the chest wall); causes the lung to collapse.
Poliomyelitis - a highly contagious infectious disease caused by various types of poliovirus. Spread though feces and airborne particles, the poliovirus usually causes no more than a mild illness. However, some of the more serious manifestations of the disease include meningitis, which can lead to extensive paralysis.
Polyarticular - a form of juvenile rheumatoid arthritis that affects five or more joints.
Polycystic kidney disease (PKD) - a genetic disorder characterized by the growth of numerous cysts filled with fluid in the kidneys.
Polycythemia vera - a blood disorder in which there is an increase in all types of blood cells, particularly red blood cells.
Polydactyly - a congenital problem characterized by an increase in the number of fingers or toes.
Polymenorrhea - too frequent menstruation.
Polymyalgia rheumatica - an inflammatory condition of unknown cause that affects the lining of joints, particularly in the shoulders and hips.
Polyp - growth that projects, usually on a stem, from a membrane in the body; can sometimes develop into cancer.
Polyposis - presence of many polyps.
Polyunsaturated fat - a type of fat found in vegetable oils and margarines that does not appear to raise blood cholesterol levels.
Pontic tooth - false tooth.
Porcelain veneers - thin shells of ceramic material that are bonded to the front of teeth to change the tooth's color, size, and/or shape.
Porphyria - group of rare, inherited, blood disorders in which cells fail to change chemicals (porphyrins) to the substance (heme) that gives blood its color.
Portal hypertension - abnormally high blood pressure in the portal vein, which supplies the liver with blood from the intestine.
Portal vein - large vein that carries blood from the intestines and spleen to the liver.
Portosystemic shunt - operation to create an opening between the portal vein and other veins around the liver.
Port-wine stains (also called nevi flammeus) - permanent flat, pink, red, or purple marks on the skin.
Positron emission tomography (PET) scan - a computer-based imaging technique that uses radioactive substances to examine body processes. For example, a PET scan of the heart provides information about the flow of blood through the coronary arteries to the heart.
Post-anesthesia care unit (also called PACU or recovery room) - the area a patient is brought to after surgery to recover.
Postcholecystectomy syndrome (also called biliary dyskinesia) - condition that occurs after gallbladder removal in which the muscle between the gallbladder and the small intestine does not work properly, causing pain, nausea, and indigestion.
Posterior chamber - the back section of the eye's interior.
Posterior cruciate ligament (PCL) - the ligament, located in the center of the knee, that controls backward movement of the tibia (shin bone).
Posterior optical segment - portion of the eye located behind the crystalline lens that includees the vitreous, choroid retina, and optic nerve.
Posterior vitreous detachment (PVD) - the separation of the vitreous from the retina.
Posteromedial shin splint - a type of shin splint that affects the back and inner part of the muscles of the shin and is caused by running and/or by wearing inappropriate footwear.
Postgastrectomy syndrome (also called dumping syndrome) - condition that occurs after removal of a portion or all of the stomach (gastrectomy). Symptoms include abdominal cramping, dizziness, diarrhea, fast heart rate, and low blood sugar.
Postlingually deafened - individual who becomes deaf after having learned language.
Post-Lyme disease syndrome (PLDS) - a condition also known as chronic Lyme disease, characterized by persistent musculoskeletal and peripheral nerve pain, fatigue, and memory impairment.
Postmenopausal bleeding - any bleeding that occurs more than six months after the last normal menstrual period at menopause.
Post-traumatic stress disorder (PTSD) - a debilitating condition that often follows a terrifying physical or emotional event causing the person who survived the event to have persistent, frightening thoughts and memories, or flashbacks, of the ordeal. Persons with PTSD often feel chronically, emotionally numb. Once referred to as "shell shock" or "battle fatigue."
Postvagotomy stasis - delayed stomach emptying; occurs after surgery on the vagus nerve.
Pouch - special bag worn over a stoma to collect stool; sometimes referred to as an ostomy appliance.
Predisposition - tendency to develop a certain disease.
Prednisolone - corticosteroid medication; usually used for inflammation.
Preeclampsia - a condition characterized by pregnancy-induced high blood pressure, protein in the urine, and swelling (edema) due to fluid retention.
Prelingually deafened - individual who is either born deaf or who lost hearing early in childhood, before learning language.
Premature - a baby born before full term or 37 weeks of gestation.
Premature ejaculation (PE) - the inability to maintain an erection long enough for mutual satisfaction.
Premenstrual dysphoric disorder (PMDD) - a much more severe form of the collective symptoms known as premenstrual syndrome (PMS), premenstrual dysphoric disorder (PMDD) is considered a severe and chronic medical condition that requires attention and treatment.
Premenstrual syndrome (PMS) - a group of physical and emotional symptoms that some women experience during their menstrual cycle. Although the symptoms usually cease with onset of the menstrual period, in some women, symptoms may last through and after their menstrual periods.
Presbycusis - loss of hearing that gradually occurs because of changes in the inner or middle ear in individuals as they grow older.
Presbyopia - a form of farsightedness in which it is difficult to focus on close objects or to read.
Preterm labor - labor that begins before the 37th week of pregnancy.
Prevalence - statistic that equals the total number of people in a population with a certain disease at a given time.
Priapism - persistent erection of the penis, usually accompanied by tenderness and pain.
Prickly heat (also called heat rash) - a rash caused by trapped sweat under the skin.
Primary sclerosing cholangitis - irritation, scarring, and narrowing of the bile ducts inside and outside the liver.
Primary site - the location where cancer begins. Primary cancer is named after the organ in which it originates. For example, cancer that starts in the kidney is always kidney cancer, even if it spreads (metastasizes) to other organs such as bones or lungs.
Proctalgia fugax - intense pain in the rectum that occasionally happens at night; caused by muscle spasms around the anus.
Proctectomy - operation to remove the rectum.
Proctitis - inflammation of the rectum.
Proctocolectomy (also called coloproctectomy) - operation to remove the colon and rectum.
Proctocolitis - inflammation of the colon and rectum.
Proctologist - physician who specializes in disorders of the anus and rectum.
Proctoscope - short, rigid metal tube used to look into the rectum and anus.
Proctoscopy - examination of the rectum and anus with a proctoscope.
Proctosigmoiditis - inflammation of the rectum and the sigmoid colon.
Proctosigmoidoscopy - endoscopic examination of the rectum and sigmoid colon.
Progesterone - a hormone secreted by the ovaries which affect many aspects of the female body, including menstrual cycles and pregnancy.
Prolactin - a hormone secreted by the pituitary gland which affects growth of the mammary glands.
Progestin - synthetic form of the female sex hormone progesterone.
Prognosis - a prediction of the likely outcome of a disease based on the condition of the patient and the action of the disease.
Prokinetic drugs - medications that cause the muscles in the gastrointestinal tract to move food.
Prolapse - condition that occurs when a body part slips from its normal position.
Prolapse of the uterus - displacement of the uterus down into the vagina caused by a weakening of supporting tissues in the pelvis.
Prostatalgia - pain in the prostate gland.
Prostate - a sex gland in men. It is about the size of a walnut, and surrounds the neck of the bladder and urethra, the tube that carries urine from the bladder. It is partly muscular and partly glandular, with ducts opening into the prostatic portion of the urethra. It is made up of three lobes: a center lobe with one lobe on each side.
Prostate acid phosphatase (PAP) - an enzyme produced by the prostate that is elevated in some patients when prostate cancer has spread beyond the prostate.
Prostatectomy - surgical procedure for the partial or complete removal of the prostate.
Prostate-specific antigen (PSA) - an antigen made by the prostate gland and found in the blood; may indicate cancer in the prostate gland.
Prostate-specific antigen (PSA) blood test - a blood test used to help detect prostate cancer by measuring a substance called prostate-specific antigen produced by the prostate.
Prostatism - any condition of the prostate that causes interference with the flow of urine from the bladder.
Prostatitis - an inflamed condition of the prostate gland that may be accompanied by discomfort, pain, frequent urination, infrequent urination, and, sometimes, fever.
Prosthesis - an artificial body part replacement.
Prosthodontist - a dental specialist who has undergone additional training and certification in the restoration and replacement of broken teeth with crowns, bridges, or removable prosthetics (dentures).
Protein - one of the three types of nutrients the body uses for energy. Protein is necessary for the formation of cells and body tissues.
Proteinuria - large amounts of protein in the urine.
Proton pump inhibitors - a class of medications that stops the production of acid in the stomach by blocking an enzyme responsible for producing the acid.
Prune belly syndrome (also called Eagle-Barrett syndrome) - condition of newborn males, in which the baby has poorly developed abdominal muscles, so the stomach looks like a shriveled prune. In addition, the testicles are undescended, and there are problems with the urinary tract.
Pruritus ani - itching around the anus.
Pseudomembranous colitis - a severe infection of the colon caused by Clostridium difficile bacteria; occurs after taking oral antibiotics, which kill bacteria that normally live in the colon.
Psoriasis - a chronic skin condition characterized by inflamed, red, raised areas that develop silvery scales.
Psoriatic arthritis - a form of arthritis associated with psoriasis, a skin and nail disease.
Psychiatrist - a medical doctor who specializes in the diagnosis and treatment of mental disorders.
Psychologist - a specialist in the study of the structure and function of the brain and related behaviors or mental processes.
Puberty - a sequence of events by which a child becomes a young adult; characterized by secretions of hormones, development of secondary sexual characteristics, reproductive functions, and growth spurts.
Pubic symphysis - anterior joint of the pelvis.
Pudendal block - pain relieving procedure used during childbirth in which an anesthetic is injected into tissues surrounding the pudendal nerves on either side of the vagina. It blocks pain in the tissues between the vagina and anus.
Pulmonary - pertains to lungs and respiratory system.
Pulmonary artery - blood vessel delivering oxygen-poor blood from the right ventricle to the lungs.
Pulmonary edema - a condition in which there is a fluid accumulation in the lungs caused by an impaired pumping function of the heart.
Pulmonary hypertension - abnormally high blood pressure in the arteries of the lungs.
Pulmonary valve - the heart valve located between the right ventricle and the pulmonary artery that controls blood flow to the lungs.
Pulmonary vein - the vessel that carries newly oxygenated blood to the heart from the lungs.
Pulse oximeter - a device that measures the amount of oxygen in the blood.
Punch grafts - small skin grafts to replace scarred skin. A hole is punched in the skin to remove the scar, which is then replaced with unscarred skin (often from the back of the earlobe). Punch grafts can help treat deep acne scars.
Pupil - the dark center in the middle of the iris through which light passes to the back of the eye.
Pupillary response - the constriction or dilation of the pupil as stimulated by light.
Purging - a process in which people with bulimia nervosa engage in a destructive pattern of ridding their bodies of the excess calories (to control their weight) by: vomiting, abusing laxatives or diuretics, taking enemas, and/or exercising obsessively.
Purines - components of certain foods that metabolize into uric acid in the body.
Pustule (also called pimple) - an inflamed lesion that looks like a pink bump.
Pyelonephritis - an infection of the kidney.
Pyloric sphincter - muscle between the stomach and the small intestine.
Pyloric stenosis - narrowing of the opening between the stomach and the small intestine.
Pyloroplasty - operation to widen the opening between the stomach and the small intestine to allow contents to pass more freely from the stomach.
Pylorus - opening from the stomach into the top of the small intestine (duodenum).
Pyogenic granuloma - red, brown, or bluish-black raised marks caused by excessive growth of capillaries.
Pyramidal pathway - a collection of nerve tracts that travel from the cerebral cortex through the pyramid of the medulla oblongata in the brainstem to the spinal cord. Within the pyramid of the medulla, fibers cross from one side of the brain to the opposite side of the spinal cord; the pyramidal pathway is intact in Parkinson's disease.