Glossary

A1c
Glycosylated hemoglobin that is usually elevated (6.5%–7.0% or higher) in people with diabetes mellitus. Normal range is 4%–5.9%.
Activated vitamin D
see calcitriol.
Adequate Intake (AI)
Amount of a nutrient that appears to support good health. Used when the RDA cannot be set due to lack of information about that particular nutrient.
Agonist
A drug that binds to a specific receptor on a cell and triggers a response in the cell by imitating the action of the natural hormone or neurotransmitter that binds to that same receptor.
Alfacalcidol
1α‑hydroxyvitamin D3. Synthetic analogue of calcitriol. Used in the treatment of hypocalcemia, hypophosphatemia, rickets, and osteodystrophy associated with various medical conditions.
American Medical Association (AMA)
Largest association of medical doctors and medical students in the United States and publisher of the Journal of the American Medical Association (JAMA).
Anabolic process
The metabolic process that builds larger molecules from smaller ones and thus uses up energy (endergonic).
Anterior pituitary
The anterior lobe of the pituitary gland and part of the endocrine system. Regulates several physiological processes including stress, growth, and reproduction through the production and secretion of peptide hormones.
Anthracosis
Noncollagenous and less‑inflammatory pneumoconiosis caused from inhaling carbon or coal dust.
Antiangiogenic
Anything which blocks the formation of new blood vessels.
Antioxidant
Compound synthesized in the body (or obtained from diet) which helps prevent the formation of, and removes, reactive oxygen species.
Apoptosis
One of the main types of programmed cell death.
Autocrine
A cell signaling itself through a chemical that it first synthesizes and then responds to. Autocrine signaling occurs either within the cell's cytoplasm or by the cell's secretion of the chemical, which then interacts with receptors on the cell's surface.
Autonomic Nervous System (ANS)
The part of the Peripheral Nervous System consisting of motor neurons that control internal organs such as muscles in the heart and smooth muscle in the intestine, bladder, and uterus. The Autonomic Nervous System has two subsystems, both of which innervate the same organs yet operate in the reverse of the other (antagonism) to maintain homeostasis: the Sympathetic Nervous System (involved in "fight or flight" response) and Parasympathetic Nervous System (involved in relaxation).