Vitamin D Council Glossary

Pandemic

An epidemic of infectious disease that spreads through populations across a large region, such as a continent or globally.

Paracrine

A cell's signaling of nearby cells by secreting a chemical that interacts with the receptors on those cells.

Parathyroid glands (Parathyroid gland)

Small endocrine glands in the neck whose sole function is to regulate the body's calcium level for proper functioning of the nervous system and muscular system.

Parathyroid Hormone (PTH,parathormone)

Hormone secreted by the parathyroid glands and the most important endocrine regulator of calcium and phosphorus concentration in extracellular fluid.

Paricalcitol ("19-nor-1,25-dihydroxyvitamin D2","19-Nor-1,25-(OH)2D2")

A noncalcemic vitamin D analog that is used in the treatment of secondary hyperparathyroidism.

Parkinson's disease (Parkinson disease)

Motor system disorder which results from the loss of dopamine-producing brain cells.

Pathogenesis

The origin of a disease and the chain of events leading to that disease.

Pathologic

Altered or caused by disease.

Pathology

The study of the nature of diseases and of the structural and functional changes produced by them.

Peptide (Peptides)

One of a family of short molecules formed from the linking of various α-amino acids.

Peptide hormone

Hormone belonging to a class of peptides that are secreted into the blood stream and have endocrine functions in living animals.

Pericarditis

Inflammation of the pericardium, the most common symptom of which is chest pain.

Pericardium

Thin layer of tissue covering the outer surfaces of the heart, protecting it from tumors, infections, and possibly enlargement.

Peripheral Nervous System (PNS)

The part of the nervous system that contains only nerves and connects the central nervous system to the rest of the body. It is composed of two major subdivisions: the somatic nervous system and the autonomic nervous system.

Pharmacodynamics

Study of what drugs and substances do to the body.

Pharmacokinetics

Study of what the body does to a drug or substance.

Pharmacological dose (Pharmacological doses)

The minimum dose needed to make a drug medically effective in treating an illness.

Pharmacology

The scientific study of drugs and their effects, especially in the treatment of disease.

Phenotype

The class to which an organism belongs as determined by the physical and behavioral characteristics of that organism.

Phosphorus (Phosphate)

Mineral macronutrient essential to all lifeforms. Phosphorus has a role in many bodily functions such as intracellular energy transfer, regulation of many biochemical processes, catalytic activity of enzymes, and oxygen dissociation from hemoglobin. The backbones of DNA and RNA are composed of phosphorus bound to sugars.

Physiological dose (Physiological doses)

The minimum dose needed to produce a physiological effect in the body.

Physiology

The normal mechanical, physical, and biochemical processes of living things.

Pineal gland

Tiny endocrine gland situated at the center of the brain that secretes melatonin.

Pituitary gland

An endocrine gland that is composed of two distinct parts: the anterior and posterior pituitary. Together, these two parts secrete several different hormones that influence all cells and affect all physiologic processes within the body.

Placebo

An inactive substance used comparatively in studies for the purpose of determining the effectiveness of a medicinal drug.

Pleomorphic

Occurring in various distinct forms, multi-functional.

Polychlorinated biphenyls (PCBs)

Organic compounds that have been shown to be carcinogenic, adversely impacting the environment and human health. Although a ban was placed on their production in the 1970s, PCBs are still present in the environment.

Polymorphism

Small genetic change or variation that can occur within a person's DNA sequence.

Polypeptide (Polypeptides)

Peptide consisting of 2 or more amino acids that is a component of protein formation.

Potassium

Essential dietary mineral and electrolyte. Normal body function depends on tight regulation of potassium concentrations both inside and outside of cells.

Prehormone

Glandular secretory product that is a precursor of a hormone but has little, or no, inherent biological potency itself.

Primary hyperparathyroidism (Hyperparathyroidism)

Disorder of the parathyroid glands in which one or more become enlarged and secrete too much parathyroid hormone (PTH), causing excessive calcium in the blood (hypercalcemia).

Prodifferentiation

The process of cell maturation and self-definition through the acquisition of additional individual characteristics.

Prohormone (Prohormones)

Any substance that can be converted to a hormone.

Prolactin (PRL)

Peptide hormone primarily associated with lactation.

Prophylactic

A medication or treatment designed and used to prevent a disease from occurring.

Prospective cohort study

Study design that follows over time groups of individuals who are similar in some respects, but different in others, and compares them for a particular outcome, such as disease. The study begins with a sample whose members are free of the disease under study.

Prospective Epidemiological Study of Myocardial Infarction (PRIME)

Multicentre prospective study of 10593 men investigating novel risk factors for coronary heart disease.

Prostate gland

Exocrine gland of the male mammalian reproductive system.

Prostate-specific antigen (PSA)

A protein produced by normal prostate cells that plays an important role in fertility.

Protein (Proteins)

One of an important class of biochemical molecules that are the major structural components of animal and human tissue and are essential for life.

Proteolysis

Digestion of proteins by cellular enzymes (called proteases) or by intramolecular digestion.

PubMed

Service of the US National Library of Medicine that includes over 16 million citations from Medline and other life science journals dating back to the 1950s.