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Pacemaker
An electronic device that is surgically implanted into the patient's heart and chest to regulate heartbeat.
Pain threshold
The point at which a stimulus causes a feeling of pain.
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 part of the brain, called the globus pallidus, is lesioned in order to improve symptoms of tremor, rigidity, and bradykinesia.
Palming
An imaging technique involving the visualization of color.
Palpitation
Sensation of rapid heartbeats.
Palsy
Paralysis of a muscle or group of muscles.
Pancreas
Long gland that lies behind the stomach; manufactures insulin and digestive enzymes.
Pap test
Microscopic examination of cells collected from the cervix. It is used to detect changes that may be cancer or may lead to cancer, and it can show noncancerous conditions, such as infection or inflammation. Also called Pap smear.
Papillary stenosis
Condition in which the openings of the bile ducts and pancreatic ducts narrow.
Parietal cells
Cells in the stomach wall that make hydrochloric acid.
Parkinsonism
The name given to a group of disorders with similar features including four primary symptoms: tremor, rigidity, postural instability, and bradykinesia, that are the result of the loss of dopamine-producing brain cells.
Parosmia
Any disease or perversion of the sense of smell, especially the subjective perception of odors that do not exist.
Parthenogenesis
The development of an individual from an egg without fertilization.
Partial colectomy
The removal of part of the large intestine.
Partial mastectomy
Surgery to remove a portion of the breast.
Passive accessory intervertebral movements (PAIVMS)
Investigation of accessory gliding movements occurring in a joint.
Passive physiological intervertebral movements (PPIVMS)
Investigation of passive physiological movements, passively, to confirm restrictions seen on active movement testing.
Patellar tendonitis
Inflammatory condition of the patellar ligament, usually due to overuse.
Pathognomonic
Characteristic or indicative of a disease, denoting especially one or more typical symptoms.
Pathologist
A doctor who identifies diseases by studying cells and tissues under a microscope.
Pathologist
Physician who identifies diseases by studying cells and tissues under a microscope.
Pathology
The study of diseases.
Pathophysiologic
Characteristic derangement of function seen in disease.
PCR
Polymerase chain reaction; a technique for copying the complementary strands of a target DNA molecule simultaneously for a series of cycles until the desired amount is obtained.
Peak flow meter
A portable, inexpensive, hand-held device used to measure how air flows from lungs in one 'fast blast' to measure the ability to push air out of the lungs.
Peak torque
Measure of isokinetic performance.
Pediatric dentist
A specialist in the field of dentristy - dealing particularly with the oral health care of children, from infancy through the teenage years.
Pedigree
A diagram of the heredity of a particular trait through many generations of a family.
Pelvic
Having to do with the pelvis, the lower part of the abdomen, located between the hip bones.
Pelvic exam
A physician examination of the uterus, vagina, ovaries, fallopian tubes, bladder, and rectum.
Pelvic lymph node dissection
Removal of some lymph nodes from the pelvis.
Penetrance
A term indicating the likelihood that a given gene will actually result in disease.
Pepsin
Enzyme made in the stomach that breaks down proteins.
Peptic
Related to the stomach and the duodenum, where pepsin is present.
Peptic ulcer
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
Process of knowing or being aware of information through the ear.
Perfusion
Flow.
Perianal
Area around the anus.
Pericardium
The membrane that surrounds the heart.
Perilymph fistula
Leakage of inner ear fluid to the middle ear that occurs without apparent cause or is associated with head trauma, physical exertion, or barotrauma.
Perineal
Related to the perineum.
Perineum
Area between the anus and the sex organs.
Period Prevalence
The number of existing cases of an illness during a period or interval, divided by the average population.
Periodontal diseases (GUM DISEASES)
Serious bacterial infections that destroy the gums and the surrounding tissues of the mouth.
Periodontist
A specialist in the field of dentristy responsible for the care and prevention of gum-related diseases, guided bone regeneration, and dental implants.
Periostitis (SHIN SPLINTS)
Inflammatory condition of the covering of the bones.
Peripheral stem cell support
A method of replacing blood-forming cells destroyed by cancer treatment. Certain cells (stem cells) in the blood that are similar to those in bone marrow are removed from the patient's blood before treatment. The cells are given back to the patient after treatment.
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.
Peritoneal adhesions
The peritoneum is a two-layered membrane that lines the wall of the abdominal cavity and covers abdominal organs. Sometimes organs begin to adhere to the peritoneum, requiring surgery to free the organs again.
Peritoneum
Lining of the abdominal cavity.
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.
Phage
A virus for which the natural host is a bacterial cell.
Phalen's test
Test for carpal tunnel syndrome in which the wrists are flexed for one minute.
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.
Phenotype
Observable characteristics of an organism produced by the organism's genotype interacting with the environment.
Phonology
Study of speech sounds.
Photophobia
Sensitivity to light.
Photorefractive keratectomy (PRK)
Surgical procedure using an excimer laser to change the shape of the cornea.
Physiatrist
The physician who specializes in physical medicine and rehabilitation.
Physical map
Map where the distance between markers is the actual distance, such as the number of base pairs.
Pituitary
Also known as the hypophysis, a gland at the base of the brain with two functionally distinct lobes involved in regulating growth, metabolism, and maturation.
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.
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.
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 warts
Warts that occur on the sole of the foot and look like calluses; often a result of an infection or a specific virus.
Plaque, dental
Film of mucus that traps bacteria on the surface of the teeth.
Plasma
The fluid portion of the blood, rich in soluble proteins with a wide range of functions.
Plasma
The watery, straw-colored fluid which carries the cellular elements of the blood through circulation.
Plasmid
Autonomously replicating, extrachromosomal circular DNA molecules, distinct from the normal bacterial genome and nonessential for cell survival under nonselective conditions. Some plasmids are capable of integrating into the host genome. A number of artificially constructed plasmids are used as cloning vectors.
Platelets
Cells found in the blood.
Pleiotropy
The phenomenon of variable phenotypes for a number of distinct and seemingly unrelated phenotypic effects.
Pneumonectomy
Removal of an entire lung, for cancer, lung abscesses, bronchiectasis, or extensive tuberculosis.
Polygenic disorders
Genetic disorders resulting from the combined action of alleles of more than one gene (e.g., heart disease, diabetes, and some cancers). Although such disorders are inherited, they depend on the simultaneous presence of several alleles; thus the hereditary patterns are usually more complex than those of single- gene disorders. Compare single-gene disorders.
Polymerase
Any enzyme that catalyzes the formation of DNA or RNA from deoxyribonucleotides or ribonucleotides.
Polymerase chain reaction (PCR)
A method for amplifying a DNA base sequence using a heat- stable polymerase and two 20- base primers, one complementary to the (+)- strand at one end of the sequence to be amplified and the other complementary to the (- )- strand at the other end. Because the newly synthesized DNA strands can subsequently serve as additional templates for the same primer sequences, successive rounds of primer annealing, strand elongation, and dissociation produce rapid and highly specific amplification of the desired sequence. PCR also can be used to detect the existence of the defined sequence in a DNA sample.
Polymerase, DNA or RNA
Enzymes that catalyze the synthesis of nucleic acids on preexisting nucleic acid templates, assembling RNA from ribonucleotides or DNA from deoxyribonucleotides.
Polymorphism
Difference in DNA sequence among individuals. Genetic variations occurring in more than 1% of a population would be considered useful polymorphisms for genetic linkage analysis. Compare mutation.
Polyp
A growth that projects from the lining of mucous membrane, such as the intestine.
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
A ceramic material that is bonded to the front of teeth to change the tooth's color, size, and/or shape.
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.
Positron Emission Tomography (PET SCAN)
Imaging technique that relies on the detection of gamma rays emitted from tissues after administration of a natural biochemical substance into which positron-emitting isotopes have been incorporated.
Positron emission tomography (PET)
A nuclear scanning procedure that gives a three-dimensional picture of the heart to provide information about the flow of blood through the coronary arteries to the heart muscle.
Post-anesthesia care unit (RECOVERY ROOM)
The area a patient is brought to after surgery to recover.
Postcholecystectomy syndrome (BILIARY DYSKINESIA)
Condition that occurs after a gallbladder removal in which the muscle between the gallbladder and the small intestine does not work properly, causing pain, nausea, and indigestion.
Posterior chamber of the eye
The back section of the eye's interior.
Posterior optical segment
Portion of the eye located behind the crystalline lens; includes the vitreous, choroid retina, and optic nerve.
Posterior vitreous detachment (PVD)
The separation of the vitreous from the retina.
Postgastrectomy syndrome
Condition that occurs after an operation to remove the stomach (gastrectomy). (See also dumping syndrome.)
Postlingually deafened
Individual who becomes deaf after having learned language.
Postvagotomy stasis
Delayed stomach emptying; often occurs after surgery on the vagus nerve.
Predictive gene tests
Tests to identify gene abnormalities that may make a person susceptible to certain diseases or disorders.
Predisposition
Tendency to develop a certain disease.
Predisposition
To have a tendency or inclination towards something in advance.
Prednisolone
One type of corticosteroid medication, usually used for inflammation.
Prelingually deafened
Individual who is either born deaf or who has lost hearing early in childhood, before learning language.
Prenatal diagnosis
Examining fetal cells taken from the amniotic fluid, the primitive placenta (chorion), or the umbilical cord for biochemical, chromosomal, or gene alterations.
Presbycusis
Loss of hearing that gradually occurs because of changes in the inner or middle ear in individuals as they grow older.
Presymptomatic diagnosis
Diagnosis of a genetic condition before the appearance of symptoms.
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.
Prick skin test
A test to determine if a person is allergic to certain substances. A physician places a drop of the substance being tested on the persons forearm or back and pricks the skin with a needle, allowing a tiny amount to enter the skin. If the person is allergi
Primary sclerosing cholangitis
Inflammation, scarring, and narrowing of the bile ducts inside and outside the liver.
Primer
Nucleotides used in the polymerase chain reaction to initiate DNA synthesis at a particular location.
Probability
The long term frequency of an event relative to all alternative events, and usually expressed as decimal fraction.
Proband
Individual in a family who brought the family to medical attention.
Probe
Single-stranded DNA labeled with radioactive isotopes or tagged in other ways for ease in identification.
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.
Proctocolectomy (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
Looking into 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. (See also endoscopy.)
Progesterone
A female hormone.
Progestin
Synthetic form of the female sex hormone progesterone.
Prognosis
A prediction of the course of the disease.
Prognosis
The probable outcome or course of a disease; the chance of recovery.
Prokaryote
Cell or organism lacking a membrane- bound, structurally discrete nucleus and other subcellular compartments. Bacteria are prokaryotes. Compare eukaryote. See chromosomes.
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.
Promoter
A site on DNA to which RNA polymerase will bind and initiate transcription.
Proofreader genes
See DNA repair genes.
Prophylactic surgery
Surgery to remove tissue that is in danger of becoming cancerous, before cancer has the chance to develop. Surgery to remove the breasts of women at high risk of developing breast cancer is known as prophylactic mastectomy.
Proprioceptive neuromuscular facilitation (PNF)
Techniques used to improve motor skills through positive motor transfer, using the principles of facilitation/inhibition; irradiation/reinforcement; reciprocal innervation.
Prostatalgia
Pain in the prostate gland.
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.
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
A large, complex molecule composed of amino acids. The sequence of the amino acids, and thus the function of the protein, is determined by the sequence of the base pairs in the gene that encodes it. Proteins are essential to the structure, function, and regulation of the body. Examples are hormones, enzymes, and antibodies.
Protein product
The protein molecule assembled under the direction of a gene.
Proton pump inhibitors
Medications that stop the stomach's acid pump.
Pruritus ani
Itching around the anus.
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; blocks pain in the tissues between the vagina and anus.
Pulmonary
Pertains to lungs and respiratory system.
Pulmonary
Relating to the lungs.
Pulmonary artery
Blood vessel delivering oxygen-poor blood from the right ventricle to the lungs.
Pulmonary hypertension
Abnormally high blood pressure in the arteries of the lungs.
Pulmonary vein
The vessel that carries newly oxygenated blood to the heart from the lungs.
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.
Purine
A nitrogen-containing, single- ring, basic compound that occurs in nucleic acids. The purines in DNA and RNA are adenine and guanine.
Pyloric sphincter
Muscle between the stomach and the small intestine.
Pylorus
Opening from the stomach into the top of the small intestine (duodenum).
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 spin
Pyrimidine
A nitrogen- containing, double- ring, basic compound that occurs in nucleic acids. The pyrimidines in DNA are cytosine and thymine; in RNA, cytosine and uracil.
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