Calcium

Calcium

Soft, silvery-white metal. Density: 1.55 g/cm³. The name derives from the Latin calx, meaning limestone. It was discovered by Humphry Davy in 1808. It reacts violently with water.

Since ancient times gypsum (calcium sulfate) and slaked lime (calcium carbonate) were known. The Colosseum and a major part of ancient Rome were built using calcium carbonate. In water, the carbonate forms a milky-white mixture used for painting walls. It is the main component of the shells of mussels and snails, which become ground down by the water and contribute to the formation of coasts.

The information carried by hormones, which the blood transports to the cell membranes, is subsequently transported to the nucleus by differently modulated calcium waves. The DNA in the nucleus then executes the “commands” of the hormones [1]. Whan a sperm reaches the egg in human fertilization, calcium waves on the surface of the egg spread out from the sperm, organizing the first cell division.

Birds with calcium deficiency tear out their feathers. Biologically, this is useful because the feathers contain calcium-filled vacuoles [2]. In atherosclerosis, calcium carbonate accumulates in the arteries. In the bones, calcium is essential. There is an average of two kilograms calcium phosphate in the skeleton of an adult.

[1] H. Rasmussen, Scientific American 1989, 261 (4), 66–73. DOI: 10.1038/scientificamerican1089-66

[2] P. Wolf, G. Bayer, C. Wendler, J. Kamphues, J. Anim. Physiol. Anim. Nutr. 1998, 80, 140–146. DOI: 10.1111/j.1439-0396.1998.tb00516.x

Calcium,
chant of cells,
spokesman of blood:
Bring me your key!
In the Calcium circus
the grieving raven
plucks out
its feathers.

Outside the door
the blunted
old woman:
her veins, her bones
become one
with the milk
of the wall.
Behind the door
a girl
– waves cross her womb –
sailor’s delight.

The sea answers
jealously.
Shells of its dwellers
within the water’s teeth
have built
their own
wall.