Central Glossary

Acute­phase proteins: Proteins found in the blood shortly after the onset of an infection that participate in the early phases of the host defense against the infection. Adaptive immunity: Response of antigen­specific immune cells when they encounter the antigen, including the develop­ ment of immunological memory; also known as acquired immunity; adaptive immune responses are distinct from innate immune responses. Affect: Emotion or subjectively experienced feeling. Acetaldehyde: A toxic product that results from the breakdown of alcohol by the enzyme alcohol dehydrogenase (ADH). Adenosine triphosphate (ATP): A molecule, generated largely in the mitochondria, that provides the energy needed for many key metabolic functions. Alcohol dehydrogenase (ADH): An enzyme that breaks down alcohol by oxidation, converting it to acetaldehyde. Allele: One of two or more variants of a gene or other deoxy­ ribonucleic acid (DNA) sequence. Different alleles of a gene generally serve the same function (e.g., code for a protein that affects eye color) but may produce different phenotypes (e.g., blue eyes or brown eyes). Some alleles may produce a product that has no function or an abnormal function. Anisotropy: Having a different value when measured in differ­ ent directions. Anisotropy is the property of being direction­ ally dependent, as opposed to isotropy, which implies homogeneity in all directions. Anterior: Towards the front of an organism; opposite of posterior. Antibodies: Immune molecules naturally produced by the body that recognize foreign or harmful molecules which have entered the body, bind to these molecules, and mark them for destruction by the body's immune system. Apoptosis: Cell death in which the affected cell participates by activating a cascade of biochemical reactions that leads to death. Atrophy: The complete or partial wasting away of parts of the body; a physiological process of tissue breakdown involving cell death. Antigen: Any molecule that can bind specifically to an antibody and generate an immune response. Antioxidant: A substance (e.g., glutathione and vitamins A and E) that inhibits oxidation, serving as a defense against harm­ ful reactive oxygen species (ROS). Arrhythmia: Any condition in which there is abnormal electri­ cal activity in the heart (i.e., the heart beat is too fast, too slow, or irregular). Atherosclerosis: Condition in which the walls of the arteries thicken because of the buildup of fatty materials, such as cholesterol; may lead to complete blockage of the artery. Atherosclerotic plaque: The buildup of cells, lipids (e.g., cholesterol), calcium, and connective tissue that forms …