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2 Organs and tissues 3 Cell biology |
Some invertebrates use Ca for building their outer (radiolaria) or inner skeleton.
There are also some plants which accumulate Ca in their tissues, thus making them more firm.
The same Ca2+ ions can, however, bring damage to cells if there are too many of them (for example in a case of overexcitation in neural circuits). This may even cause cell apoptosis.
See also: Ca-binding proteinsBiochemistry
Calcium plays a vital role in the biochemistry of the cell, particularly in signal transduction pathways. The skeleton acts as a major storage site for the element and releases Ca2+ into the bloodstream under controlled conditions. Circulating calcium is either in the free, ionized form or bound to blood proteins such as albumin. The hormone secreted by the parathyroid gland, parathyroid hormone, regulates the resorption of Ca2+ from bone. Organs and tissues
Different tissues contain Ca in diffent concentrations. In vertebrates Ca (in a form of CaSO4) is the most important (and specific) element of bones.Cell biology
In cell biology Ca2+ ions are one of the most widespread messengers, their entrance into cytoplasm (either from outside the cell through cell membrane or from some internal Ca storages) represent the most important sign for the whole cell machinery. Ca2+ entering the cell causes the specific action of this cell, whatever this action is: secretory cells release vesicles with their secretion, muscle cells contract, synapses go into processes of synaptic plasticity etc.