Calcium biological distribution

Similarly, the serum electrolytes (sodium, potassium, and calcium) interact with each other a decrease in one is frequently tied, for instance, to an increase in one of the others. Furthermore, the nature of the data (in the case of some parameters), either because of the biological nature of the parameter or the way in which it is measured, is frequently either not normally distributed (particularly because of being markedly skewed) or not continuous in nature. This can be seen in some of the reference data for experimental animals in Mitruka and Rawnsley (1957) or Weil (1982) in, for example, creatinine, sodium, potassium, chloride, calcium and blood. 

Calcium, in contrast to magnesium, does not have an important function as an enzyme activator, in accord with its different distribution. It is very important, however, in the control and triggering of biological processes such as muscle contraction and the release of various chemicals, including hormones, defence chemicals and neurotransmitters. This occurs when, in response to some stimulus, the normal selectivity of the cell membrane or the membranes of internal organelles breaks down, and calcium ions are allowed to enter the cell. These bind to specific sites and trigger certain reactions. 

The biological significance of these studies is that they demonstrate that the effect of say calcium ions on membrane structures could be significant. Now in biology calcium ions are distributed unevenly being at < 10-7 M inside cell and > 10-3 M outside cells. Thus the binding is much more likely to the outside of the bilayer which could cause two effects... 

The enzymes called ATP phosphohydrolase are widely distributed in the evolutionary chain and in biological systems. In some cases the ATPase is activated either by magnesium (Mg2+ ATPase) or by calcium (Ca2+ ATPase), and in other cases by both calcium and magnesium (Ca2+ Mg2+ ATPase). Another class of ATPase is stimulated by sodium and potassium and is inhibited by ouabain being denominated Na+ K+ ATPase. There are some ATPases that hydrolyze other nucleotides than ATP, however, with a high preference for ATP. 

The main components of marine sediments are inorganic aluminosilicate minerals which are usually accumulated on the sea floor by river and other geological activities, and also skeletons and shells of marine organisms (mainly calcium carbonate and silica) [2]. Of course, some metal salts or particulates which precipitate from seawater form new minerals, e.g. manganese nodules [2]. The chemical compositions of the three principal types of sediments in the ocean are shown in Table 12 [105], Most of the sediments found in the deep-sea floor are mixtures of these three principal minerals. Study of the sediments in the oceans and seashores can provide important data related to geochemical, oceanographical or biological circulation and deposition of elements, formation and distribution of marine sediments, and exploitation of marine resources. 

Approximately fifteen minerals are considered nutrients calcium, chromium, cohalt, copper, iron, magnesium, manganese, molybdenum, nickel, phosphorus, selenium, silicon, tin, vanadium, and zinc) of these minerals, those in italics are essential to mammalian nutrition. Minerals, which are important for good nutrition, are supplied in an organism s diet. However, we have recently realized that the biological availability of the minerals from their food sources is also important in nutrition (J). Internal metabolism, distribution, and retention are less important factors in mineral nutrition. 

Metal ions in biological systems tend to be distributed between four different states in vivo. First, there is the inert form of the metal complex whereby it is laid down into a solid matrix, just like the calcium in the apatite of bones and teeth (Scheme 1). Secondly, there are the three states of metal-protein having reversibly bound metal ions, known as high molar mass species, that are in turn in equilibrium with low molecular mass complexes and, for purely thermodynamic reasons, there must be the occasional aquated metal ion, although this is highly unlikely with a pH of 7.4 because of the threat of hydrolysis. 

A standard preparation of thyrocalcitonin, prepared to the salt-fractionation stage by Method 2 above, is available from the Medical Research Council, Department of Biological Standards, National Institute for Medical Research, Mill Hill, London, and is distributed in ampules containing 0.25 MRC unit. When 0.01 MRC unit is injected intravenously into a 150-g rat, it produces a fall of approximately 10% in the plasma calcium after 50 minutes, i.e., this new unit is approximately 100 times larger than that described by Hirsch et al. (H4) and 1000 times larger than that of Baghdiantz et al. (Bl). From the in-... 

EP4, exert their biologic effect by the coupling of G proteins to cAMP, whereas, EPl receptor action is coupled by increasing intracellular calcium. The existence of EP2 receptor in the kidney remains to be confirmed. Breyer et al. [14] has recently reviewed the distribution of the EP receptors known to exist in the kidney. EP4, IP, and possible EP2 are located in the glom-... 

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