Growth and maintenance of bone

Like their neighbors sodium and potassium, magnesium and calcium are relatively abundant on Earth and in seawater and are essential for living organisms as cations in ionic compounds. Calcium is particularly important for growth and maintenance of bones and teeth. 

Silicon (Si) 3000 mg Needed for growth and maintenance of bone and teeth, tendons and ligaments, hair and skin... 

Vitamin A, as retinal, has a clearly established role in vision (Chapter 23) and apparently has a specialized function in reproduction. In vitamin A deficiency no sperm cells are formed in males, and fetal resorption occurs in females. Rats deprived of vitamin Abut fed retinoic acid become blind and sterile but otherwise appear healthy.e bb Evidently either the alcohol or the aldehyde has an essential function in reproduction, whereas bone growth and maintenance of mucous secretions requires only retinoic acid. Indeed, retinoic acid is 100 to 1000 times more active than other forms of vitamin A in these differentiation functions.1 ... 

The principal cell in cartilage is the chondrocyte. Responsible for matrix production during growth and maintenance of the matrix in mature tissue, chondrocytes occupy only about 10 percent of the overall tissue volume (Mankin et al., 1994). Due to the avascular nattire of articular cartilage, the provision of metabolites to the cells is assumed to occur via diffusion from the synovial fluid or, to a lesser extent, the underlying bone (Mankin et al., 1994). However, the lack of blood supply severely diminishes the ability of cartilage to heal once it has been damaged. 

Because of the possibility of its biosynthesis in the body and its biological function (it is an antirachitic vitamin connected with the metabolism of calcium and phosphorus, which are necessary for growth, development and maintenance of bone structure), some reports state that vitamin Dj is more a hormone than a vitamin. 

Many cytokines play a regulatory role in processes other that immunity and inflammation. Neurotrophic factors, such as NGF and BDNF, regulate growth, development and maintenance of various neural populations in the central and peripheral nervous system. EPO stimulates the production of red blood cells from erythroid precursors in the bone marrow. 

Certain human populations depend on dietary sources of vitamin D because of insufficient biosynthesis of the vitamin due to inadequate skin exposure to sunlight. The classic symptoms of vitamin D deficiency are rickets in children and osteomalacia in adults. 25-Hydroxyvitamin D3 is the major circulating metabolite in the blood, but the hormonally active form of the vitamin is 1,25-dihydroxyvitamin D3. The latter metabolite stimulates the intestine to absorb calcium and phosphate by two independent mechanisms and acts with parathyroid hormone to mobilize calcium, accompanied by phosphate, from the bone fluid compartment into the bloodstream. 1,25-dihydroxyvitamin D 3 is also involved in the formation of osteoclasts—giant cells that are solely responsible for the resorption of bone matrix (33). Resorption is an essential process for the development, growth, maintenance, and repair of bone. 

Vitamin A has essential roles in vision, bone and muscle growth, reproduction and maintenance of healthy epithelial tissue. Naturally occurring precursors of vitamin A are found in some seeds, leafy green vegetables and forages such as lucerne. The common form of the precursor is p-carotene, which can be converted into vitamin A in the intestinal wall. Carotene is present in considerable quantities in pasture, lucerne hay or meal, and yellow maize. Carotene and vitamin A are rapidly destroyed by exposure to air, light and rancidity, especially at high temperature. Since it is difficult to assess the amount of vitamin A present in the feed, diets should be supplemented with this vitamin. 

To assess the impact of exercise on the needs for specific nutrients, nutrient functions must be evaluated. At a generalized level, the functions of nutrients are (a) growth or maintenance of the structures of the body (one can consider either macro-structures like muscles and bones, or micro-structures like cell membranes and enzymes), (b) fuels for the energy to run the body processes, (c) fluids and regulation of body fluids, and (d) protection from toxic substances including toxic chemicals, carcinogens, and antigens. 

A needed for normal vision, reproduction, and maintenance of healthy skin, mucous membranes, bones, red blood cells, cell differentiation, and im-mune fimction night blindness, xerophthalmia, loss of appetite, increased susceptibiHty to infections, skin disorders, poor growth, defective reproduction regression of precancerous lesions, reduces measle-associated morbidity in children... 

Foods may contain precursors of vitamin D as well as vitamin D. The precursors are converted to the vitamin following their absorption from the diet. T c body is a source of one of the precursors, 7-dehydnocholesteroL Conversion of the precursor to the vitamin form occurs in the skin. The major function of vitamin D is to maintain the concentration of calcium ions in the plasma. Maintenance of these concentrations is vital for normal functioning of the nervous system and for the growth of bones and the maintenance of bone mass. Although vitamin D is closely associated with bone growth, it is thought that the relationship is only indirect. T he vitamin stimulates the absorption of dietary calcium by the gut, but it seems not to stimulate the subsequent deposit of calcium in the bone. 

Other related effects These include the development of libido at puberty maintenance of the. sex drive in the adult male controlling the secretion of LH by the anterior pituitary via feedback mechanisms the development and maintenance of male secondary sexual characteristics and general protein anabolic effects, including bone growth and induction of aggressive behavior. Low levels of testosterone and decreased libido lead to ED. 

Although not produced by the human body, these Essential Fatty Acids (EFAs) are required for normal brain function, growth, development, bone health, stimulation of skin and hair growth, regulation of metabolism, and maintenance of reproductive processes (University of Maryland Medical Centre, 2008). The health benefit provided by PUFAs is dependent on the precise PUFA being taken. The health benefits of the fish derived PUFAs eicosapentanoic acid and docosahexanoic acid are well described (Sanderson et al., 2002). There is interest in... 

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