Human body calcium

Beryllium is found in emeralds, which are a variety of the mineral beryl. Perhaps the best-known alkaline-earth metal is calcium, an important mineral nutrient found in the human body. Calcium is essential for muscle contraction. Bones are made up of calcium phosphate. Calcium compounds, such as limestone and marble, are common in the Earth s crust. Marble is made almost entirely of pure calcium carbonate. Because marble is hard and durable, it is used in sculptures. 

Calcium is essential to all living things. Calcium compounds are a vital component of the skeletons and bones of mammals, amphibians, reptiles, birds, fish, and other land and marine animals. The most abundant metal in the human body, calcium makes up the bones and serves other functions in the body s metabolic system. These functions include keeping cells joined together, aiding in muscle contraction and conduction of nerve impulses, helping blood clot, and controlling cell division. 

A pilot study on the use of natural calcium isotope ( Ca/ Ca) fractionation in urine as a proxy for the human body calcium balance. Bone, 46, 889-896. 

Calcium. Calcium, the most abundant mineral element in mammals, comprises 1.5- -2.0 wt % of the adult human body, over 99 wt % of which... 

Phosphorus. Eighty-five percent of the phosphoms, the second most abundant element in the human body, is located in bones and teeth (24,35). Whereas there is constant exchange of calcium and phosphoms between bones and blood, there is very Httle turnover in teeth (25). The Ca P ratio in bones is constant at about 2 1. Every tissue and cell contains phosphoms, generally as a salt or ester of mono-, di-, or tribasic phosphoric acid, as phosphoHpids, or as phosphorylated sugars (24). Phosphoms is involved in a large number and wide variety of metaboHc functions. Examples are carbohydrate metaboHsm (36,37), adenosine triphosphate (ATP) from fatty acid metaboHsm (38), and oxidative phosphorylation (36,39). Common food sources rich in phosphoms are Hsted in Table 5 (see also Phosphorus compounds). 

Sodium or calcium EDTA binds to metals, such as nickel, copper, and iron, making them unavailable to react with other ingredients in a product, or with compounds in the human body. 

Another important function of albumin is its ability to bind various ligands. These include free fatty acids (FFA), calcium, certain steroid hormones, bilirubin, and some of the plasma tryptophan. In addition, albumin appears to play an important role in transport of copper in the human body (see below). A vatiety of drugs, including sulfonamides, penicilhn G, dicumarol, and aspirin, are bound to albumin this finding has important pharmacologic implications. 

Calcium exists in the human body as Ca(II) protein-bound and free Ca (II) ions (Dilana et al. 1994). For total extracellular Ca in plasma, serum and urine a definitive isotope dilution-mass spectrometry (ID-MS) method exist. Free Ca(II) in plasma/serum can be determined with PISE, but no definitive and reference methods exist. For Ca in faeces, tissue and blood flame atomic absorption (FAAS) is used widely. 

Human body fluid and SBF contain calcium and phosphate ions that are already supersaturated with respect to hydroxyapatite [20]. However, these fluids do not spontaneously deposit hydroxyapatite under normal conditions. This is because the activation energy barrier for hydroxyapatite nudeation is very high. Therefore, the ability of substrates to induce heterogeneous nudeation of hydroxyapatite and the degree of supersaturation of SBF with respect to hydroxyapatite are important factors for hydroxyapatite formation on materials in the body fluid and SBF. 

Nitrogen and phosphorus are the last on our list of the main elements making up the human body. Hydrogen, oxygen, and carbon compose 93 pounds of a 100-pound person. Calcium adds another two pounds. Nitrogen is three percent of the human body, and phosphorus is one percent, so that means they total four of those 100 pounds, and these six elements total 99 pounds. Only one pound is left for all the other elements found in the body. 

Calcitonin is a polypeptide hormone that (along with PTH and the vitamin D derivative, 1,25-dihydroxycholecalciferol) plays a central role in regulating serum ionized calcium (Ca2+) and inorganic phosphate (Pi) levels. The adult human body contains up to 2 kg of calcium, of which 98 per cent is present in the skeleton (i.e. bone). Up to 85 per cent of the 1 kg of phosphorus present in the body is also found in the skeleton (the so-called mineral fraction of bone is largely composed of Ca3(P04)2, which acts as a body reservoir for both calcium and phosphorus). Calcium concentrations in human serum approximate to 0.1 mg ml-1 and are regulated very tightly (serum phosphate levels are more variable). 

Bone is the main source of calcium in the human body. Osteoporosis, decreased calcium salt reserves in the body, has become the most prevalent bone disease in the U.S., being especially prevalent among post-menopausal women (1). Typical signs of this debilitating condition include backache with spasms, wedge fractures of the dorsal and lumbar vertebrae, and hip fractures (2). 

Since this increased calcium loss, the quality of dietary protein may be important in conserving body calcium in the bone reservoir via the kidney. Human renal studies have corroborated animal data in-so-far as calcium excretion as influenced by urinary acidity is concerned. This was emphasized by Marone et al. (15) who reported increased excretion of calcium in the acidotic dog and by Zemel, et al. (27) who studied calcium filtration by the kidney. They fed subjects low or high-protein (50 or 150 g/d) diets, then compared... 

Calcium is present in a number of products used in our everyday lives. It is found in classroom chalk, teeth, and bones. About 2% of the human body consists of various forms of calcium compounds. Calcium is an essential inorganic element (usually in compound form) for plant and animal life. 

Calcium is an important ingredient in the diets of all plants and animals. It is found in the soft tissues and fluids of animals (e.g., blood) as well as in bones and teeth. Calcium makes up about 2% of human body weight. 

As the human body is able to store many minerals, deviations from the daily ration are balanced out over a given period of time. Minerals stored in the body include water, which is distributed throughout the whole body calcium, stored in the form of apatite in the bones (see p. 340) iodine, stored as thyroglobulin in the thyroid and iron, stored in the form of ferritin and hemosiderin in the bone marrow, spleen, and liver (see p. 286). The storage site for many trace elements is the liver. In many cases, the metabolism of minerals is regulated by hormones—for example, the uptake and excretion of H2O, Na, ... 

Cholecalciferol (D3) and its active form 1,25-di-hydroxycholecalciferol are only to a certain extend vitamins because they can be synthesized by the human body. However deficiencies resulting in rickets in children and osteomalacia in adults do exist. Cholecalciferol can be synthesized by humans in the skin upon exposure to ultraviolet-B (UVB) radiation from sunlight, or it can be obtained from the diet. Plants synthesize ergosterol, which is converted to vitamin D2 (ergocalciferol) by ultraviolet light. Vitamin D2 may be less active in humans. Vitamin D promotes uptake of calcium and phosphate in the intestine and it stimulates osteoclasts to break down hydroxyapatite and release calcium into blood. Vitamin D is discussed in more detail in Chapter 24, Section V.a. 

Calcium in Plant and Animal Nutrition. Calcium is essential to plant and animal life and is present in adequate amounts in many soils (78). The outer green leaves of cabbages and certain other leafy vegetables contain much more calicum than the inner white ones (79, 80, 81). Large amounts of it are present in the human body. The composition of bone suggests that it must be closely related to the apatite series of minerals, which have the formula nCa3(PO.t )2-CaC03, in which n has a value... 

Another example of an undesirable precipitation reaction involves the formation of kidney stones in the human body. The major type of kidney stones consists of calcium in combination with oxalate ). The... 

The insoluble Ca(II) salts of weak acids, such as calcium phosphate, carbonate, and oxalate, serve as the hard structural material in bone, dentine, enamel, shells, etc. About 99% of the calcium found in the human body appears in mineral form in the bones and teeth. Calcium accounts for approximately 2% of body weight (18,19). The mineral in bones and teeth is mosdy hydroxyapatite [1306-06-5] having unit cell composition Ca10(PO4)6(OH)2. The mineralization process in bone follows prior protein matrix formation. A calcium pumping mechanism raises the concentrations of Ca(II) and phosphate within bone cells to the level of supersaturation. Granules of amorphous calcium phosphate precipitate and are released to the outside of the bone cell. There the amorphous calcium phosphate, which may make up as much as 30—40% of the mineral in adult bone, is recrystallized to crystallites of hydroxyapatite preferentially at bone collagen sites. These small crystallites do not exceed 10 nm in diameter (20). 

Like Na+, the calcium ion is actively excluded from cells. Indeed, 99% of the calcium in the human body is present in the bones/ 3 The blood serum concentration of Ca2+ is -3 mM, of which 1.5 mM is free. The rest is chelated by proteins, carbohydrates, and other materials. Within cells the concentration of free Ca2+ is < 1 pM and typically -0.05-0.2 pM for unexcited cells. d -f However, the total intracellular Ca2+ is considerably higher and may be in excess of 1 mM. Approximate total concentrations are red blood cells, 20 pM liver, 1.6 mM and heart, 4 mM. 

In most animals. Including the human body, this occurs mainly in the upper portion of the. small intestine. The amount and, therefore, the fraction of calcium absorbed from the gut are a function of intake, age, nutritional status, and health. Generally, the fraction absorbed decreases with age and inlake and as the nutritional status improves. The absolute amount absorbed increases wilh inlake and may or may noi decrease with age. The mechanisms by which calcium is absorbed are not well understood. Active transport of the ion against an electrochemical gradient seems to he involved, but not all of the calcium appears to he absorbed by ways of this process, because... 

Calcium. Calcium, ihe most abundant mineral element in mammals, comprises 1.5-2.0 w1 G of Ihe adult human body, over 99 wt (i of which is present in bones nnd teeth. About 48 of scrum calcium is ionic, ca 46G is bound nr hlood proteins, the rest is present as diffusible complexes, e.g.. of citrate. The calcium ion level must he maintained within definite limits... 

Calcium is also found in the rigid structural components of living things, either as the calcium carbonate of the shells of shellfish or the calcium phosphate of bone. About a kilogram of calcium is present in an adult human body, mostly in the form of insoluble calcium phosphate, but also as Ca2T ions in other fluids inside our cells. The calcium in newly formed bone is in dynamic equilibrium with the calcium ions in the body fluids, so calcium must be part of our daily diet to maintain bone strength. 

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