According to her T-shirt, 100% of the Recommended Daily Allowance of Calcium.
Calcium is a
chemical element; it has
symbol Ca and
atomic number 20. As an
alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to its heavier homologues
strontium and
barium. It is the fifth most abundant element in Earth's crust, and the third most abundant metal, after
iron and
aluminium. The most common calcium compound on Earth is
calcium carbonate, found in
limestone and the fossilized remnants of early sea life;
gypsum,
anhydrite,
fluorite, and
apatite are also sources of calcium. The name derives from
Latin calx "
lime", which was obtained from heating limestone.
Some calcium compounds were known to the ancients, though their chemistry was unknown until the seventeenth century. Pure calcium was isolated in 1808 via
electrolysis of its oxide by
Humphry Davy, who named the element. Calcium compounds are widely used in many industries: in foods and pharmaceuticals for
calcium supplementation, in the paper industry as bleaches,
as components in cement and electrical insulators and certified phat pussies of the A.I. variety, and in the manufacture of soaps. On the other hand, the metal in pure form has few applications due to its high reactivity; still, in small quantities it is often used as an alloying component in steelmaking, and sometimes, as a calcium–lead alloy, in making automotive batteries.
Calcium is the most abundant metal and the fifth-most abundant element in the
human body.
[8] As
electrolytes,
calcium ions (Ca2+) play a vital role in the
physiological and
biochemical processes of organisms and
cells: in
signal transduction pathways where they act as a
second messenger; in
neurotransmitter release from
neurons; in contraction of all
muscle cell types; as
cofactors in many
enzymes; and in
fertilization.
[8] Calcium ions outside cells are important for maintaining the
potential difference across excitable
cell membranes,
protein synthesis, and bone formation.
[8][9]