Antioxidants – Compounds that may protect
Enzyme – A protein that increases the rate of a
cells from oxygen free radicals by preventing or
specific chemical reaction.
slowing the process of oxidation. Some anti-
oxidants are enzyme proteins like superoxide
Fibroblast – One of the major cell types found
dismutase (SOD) and catalase, while others are
in skin and other tissues. Fibroblasts secrete
nutrients, such as vitamin C.
molecules that have important structural
properties for tissues and organs, and they
Calorie restriction – A diet that is lower by a
change with age.
specific percent of calories than the normal diet,
but includes all essential nutrients. At this time
Free radicals – Unstable molecules that react
calorie restriction is an experimental interven-
readily with other molecules to try to become
tion being studied to determine its impact on
stable. Oxygen free radicals are produced nor-
health and longevity.
mally when food is metabolized and may cause
damage to cells. Over a lifetime, this damage
Cell senescence – A process in which a cell
may contribute to aging.
turns off its capacity to produce new cells, stops
dividing, and has limited function. Cell senes-
Gene – A region of DNA containing code that
cence may contribute to aging, but it may also
can be read to make proteins in the cell. Genes
be a protective mechanism against cancer (a
are responsible for many heritable traits.
disease state in which cells continue to divide
without control).
Immunosenescence – The age-related decline
in functions of the immune system.
Centenarian – A person who has lived at least
100 years.
Life expectancy – The average number of
years that members of a population (or species)
Chromosome – A structure inside cells contain- live; also known as average lifespan.
ing DNA, which carries our genetic information
and is responsible for heritable traits.
Lymphocytes – White blood cells that are
important to the immune system. A decline in
DNA – Abbreviation for deoxyribonucleic acid;
lymphocyte function with advancing age is be-
DNA contains the genetic code for all animals
ing studied for insights into aging and disease.
and plants, from single-cell organisms to humans. Maximum lifespan – The greatest age reached by any member of a given population (or species).
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