Calcium is an abundant and important element
“GFP”? No, it does not mean ‘Guns for Peace’ or ‘Golden Flower Pot’. It stands for Green Fluorescent Protein, a substance for the discovery of which the three scientists O. Shimomura, R.Tsien and M. Chalfie were awarded the Nobel Prize in Chemistry in 2008. The GFP is inextricably connected with indicating the presence of calcium ions and calcium is one of the most important elements with multiple functions in our body ad that of animals.
Calcium is the 5 th most abundant element on Earth and in combination with carbon and oxygen forms a hard and durable construction material termed limestone, widely used by animals. Bound to sulphate it is known as Plaster-of-Paris or “gypsum” and as a phosphate salt it is incorporated into bones and teeth. Prof. Simkiss of Reading University had suggested that condense water from the respiration of the chick embryo at the blunt pole of the egg dissolves shell calcium on the inside, allowing it to be used by the growing embryo. But of course not only a chick but a human embryo also needs calcium for growing bone and it gets it from its mother’s bones during pregnancy and later through breast milk. So called osteoclast cells nibble away her bone material and make the calcium locked in it available to the blood from where it would then be accessible to the embryo or become part of the milk. So important is the calcium that even a hormone (the calcitonin) is named after it. This hormone, which stems from the thyroid gland can stop the osteoclasts, if they remove too much bone material. However, calcitonin’s actions are balanced by the parathyroid hormone.
There are many more roles than just adding strength to bones that calcium has. It is, for example, of fundamental importance in the process of blood clotting and activates numerous enzymes, including amylase, a saliva substance involved in the breakdown of starch. Without calcium ions transmissions of neuronal signals from nerve cell to nerve cell would be impaired and muscular contraction as well as relaxation would be impossible. Calcium ions are involved in the hearing process, the ability of cells to adhere to one another, the control of flagellar beating and cell movements. The intracellular machinery of microtubules depends on calcium and in one of my courses I used to ask students to record what happens when a tiny piece of fish skin is exposed to elevated calcium salt levels: it darkens, because of an abnormal dispersion of pigment grains along intracellular microtubular routes.
Within cells, calcium ions act as messengers, but to get there, calcium needs to be taken up by the blood from the gut. This process is oxygen- and energy-dependent and can occur against a concentration gradient, but it is, apparently, modifiable by vitamin D. The enormous importance that calcium plays in biological systems can be gauged from the fact that in the last 20 years alone at least 25,000 research papers were published and entire journals dedicated to calcium like, e.g., “Cell Calcium” exist. I suppose with all this stress on the need of calcium, I ought to mention the best sources of calcium (apart from calcium tablets): obviously there’s milk, but there are oil sardines too; in fact all small fish that one eats whole, bones and all. Let me culminate this calcium essay by pointing to the denning mother brown bear in her winter hibernation of many months: she does not eat, she does not drink, she gives birth and suckles her newborns and…..? She does not suffer osteoporosis (brittlebones). How she manages that researchers are only too keen to find out.
© Dr V.B. Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com, 2018.
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