Glossary of Terms & Definitions
Listed Alphabetically - "P"

Palliative: Serving to relieve or alleviate without curing.

Palpate: To examine by touch or feel.

Palpitaion:  The fluttering of the heart or abnormal rate of rhythm of the heart.

Pancreas: A small organ located behind the stomach. The head of the pancreas is connected to the duodenum (the first section of the small intestine). The pancreas makes enzymes that help digest food in the small intestine and hormones, including insulin, that control the amount of glucose in the blood.

Parathyroid glands: Glands located behind the thyroid gland in the neck. The parathyroid glands secrete a hormone called parathormone (PTH) that is critical to calcium and phosphorus metabolism. 

Parkinson's disease: A  disease of the nervous system caused by degeneration of a part of the brain called the basal ganglia, and by low production of the neurotransmitter dopamine. Symptoms include muscle rigidity, tremors, and slow voluntary movement. 

Pathogen: Disease causing agent, such as a virus or a bacteria.

Peptic ulcer disease: A disease characterized by ulcers or breaks in the inner lining (mucosa) of the stomach or duodenum (region of the small intestine closest to the stomach). The three major causes of peptic ulcer disease are non-steroidal anti-inflammatory drugs (NSAIDS), chronic Heliobacter pylori infection, and states of acid hypersecretion, like Zollinger-Ellison syndrome.

Peptide: A chain of amino acids. A protein is made up of one or more peptides.

Peptide hormones: Hormones that are proteins, as opposed to steroid hormones, which are made from cholesterol. Insulin is an example of a peptide hormone.

Peripheral vascular diseases: Diseases of the vessels of the extremities such as atherosclerosis, resulting in diminished circulation, pain (claudication), or a blood clot, for example.

Pernicious anemia: The end stage of an autoimmune inflammation of the stomach, resulting in destruction of stomach cells by one's own antibodies.  Progressive destruction of the cells that line the stomach cause decreased secretion of acid and enzymes required to release food bound vitamin B-12.  Antibodies to intrinsic factor (IF) bind to IF preventing formation of the IF-B-12 complex, further inhibiting vitamin B-12 absorption.

PET scan:  Positron emission tomography. A diagnostic imaging technique that uses a sophisticated camera and computer to produce images of how a person's body is functioning. A PET scans shows the difference between healthy and abnormally functioning tissues.

pH:  A measure of acidity or alkalinity.

Pharmacologic dose:  The dose or intake level of a nutrient many times the level associated with the prevention of deficiency or the maintenance of health.  A pharmacologic dose is generally associated with the treatment of a disease state and considered to be a dose at least 10 times greater than that needed to prevent deficiency.

Phenylketonuria (PKU):  An inherited disorder resulting in the inability to process the amino acid, phenylananine. If not treated, the disorder may result in mental retardation. Treatment is a diet low in phenylalanine. Newborns are screened for PKU, in order to determine the need for treatment before brain damage occurs.

Phlebotomy: The removal of blood from a vein. Phlebotomy may be used to obtain blood for diagnostic tests or to treat certain conditions, for example, iron overload in hemochromatosis.

Phospholipids Lipids (fat molecules) in which phosphoric acid as well as fatty acids are attached to a glycerol backbone. Phospholipids are found in all living cells and in the bilayers of cell membranes.

Phosphorylation:  The creation of a phosphate derivative of an organic molecule. This is usually achieved by transferring a phosphate group (-PO4) from ATP to another molecule.

Physiologic dose:  The dose or intake level of a nutrient associated with the prevention of deficiency or the maintenance of health.  A physiologic dose of a nutrient is not generally greater than that which could be achieved through a conscientious diet, as opposed to the use of supplements.

Pituitary gland:  A small oval gland located at the base of the brain that secretes hormones regulating growth and metabolism. The pituitary gland is divided into two separate glands, the anterior and posterior pituitary glands, which each secrete different hormones.

Placebo:  A sugar pill or false treatment that is given to a control group while the experimental group is given the experimental treatment. Placebo-controlled studies are conducted to make sure that significant outcomes of a trial are due to the experimental treatment rather than another factor associated with participating in the study.

Placenta:  A temporary organ joining the mother and unborn child (fetus). The placenta transfers oxygen and nutrients from the mother to the fetus, and permits the release of carbon dioxide and waste products from the fetus.

Placental abruption:  Premature separation of the placenta from the wall of the uterus. Abruption is a potentially serious problem both for the mother and baby.

Plasma:  The liquid part of blood (as opposed to blood cells) that makes up about half its volume. Plasma differs from serum in that the blood sample has not clotted. A centrifuge is used to separate plasma from cells in the laboratory.

Platelet:  Irregularly shaped cell fragments that assist in blood clotting. During normal blood clotting platelets aggregate (group together) to prevent hemorrhage.

Pneumonia:  A disease of the lungs, characterized by inflammation and accumulation of fluid in the lungs. Pneumonia may be caused by infectious agents (e.g., viruses or bacteria) or by inhalation of certain irritants.

Polymorphism:  The existence of two (or more) forms of a gene with each form being too common to be due merely to new mutation.

Polyp:  A benign (non-cancerous) mass of tissue that forms on the inside of a hollow organ, such as the colon.

Precursor: A molecule which is an ingredient, reactant, or intermediate in a synthetic pathway for a particular product.

Preeclampsia:  A condition characterized by a sharp rise in blood pressure during the third trimester of pregnancy. High blood pressure may be accompanied by edema (swelling), and kidney problems, as evidenced by protein in the urine. Although preeclampsia is relatively common, occurring in about 5 percent of all pregnancies and more frequently in first pregnancies, it can be a sign of serious problems. In some cases, untreated preeclampsia can progress to eclampsia, a life-threatening situation for both mother and baby.

Prevalence:  The proportion of a population with a specific disease or condition at a given point in time.

Prognosis :  Predicted outcome based on the course of a disease.

Proliferation:  Rapid cell division.

Prooxidant:  An atom or molecule that promotes oxidation of another atom or molecule by accepting electrons. Examples of prooxidants include free radicals, reactive oxygen species (ROS) and reactive nitrogen species (RNS).

Prophylaxis:  Prevention, often refers to a treatment used to prevent a disease. 

Prospective study:  A study in which participants are initially enrolled, examined or tested for risk factors (e.g., nutrient intake), and then followed up at subsequent times to determine their status with respect to the disease or condition of interest.

Prostaglandin:  Any of a class of hormone-like, regulatory molecules constructed from polyunsaturated fatty acids such as arachidonate. These molecules participate in a number of functions in the body, such as smooth muscle contraction and relaxation, vasodilation, and kidney regulation.

Prostate:  A gland situated at the beginning of the urethra (passage through which urine leaves the body) in men. It secretes an alkaline fluid which is the major component of semen (ejaculatory fluid).  Prostate cancer is the second leading cause of death in men in the U.S.

Protein:  A complex organic molecule composed of amino acids in a specific order. The order is determined by the sequence of nucleic acids in a gene coding for the protein. Proteins are required for the structure, function, and regulation of the body's cells, tissues, and organs, and each protein has unique functions.

Proteoglycan:  A large compound comprised of protein and polysaccharide units known as glycosaminoglycans (GAGs). GAGs are polymers of sugars and amino sugars, such as glucosamine or galactosamine. Proteoglycans are integral components of structural tissues such as bone and cartilage.

Psoriasis A chronic skin condition often resulting in a red, scaly rash located over the surfaces of the elbows, knees, scalp, and around or in the ears, navel, genitals or buttocks. Approximately 10-15% of patients with psoriasis develop joint inflammation (psoriatic arthritis). Psoriasis is thought to be an autoimmune condition.

Pyruvate kinase deficiency:  A hereditary deficiency of the enzyme pyruvate kinase. Pyruvate kinase deficiency results in hemolytic anemia.