minerals and mining 3

75 5 0
  • Loading ...
1/75 trang

Thông tin tài liệu

Ngày đăng: 30/11/2016, 13:59

Minerals Minerals • minerals are elements of the periodic table • more than 25 have been isolated • 21 elements have been shown to be essential (excluding C,H, and O) • minerals make up about to 5% of body weight (for a 70 kg individual: 2.8 kg) • many minerals are found in ionic form (others as ligands or covalent compounds) Minerals • Two categories: • macrominerals > 0.005% • microminerals < 0.005% • macrominerals are essential at levels of 100mg or more per day for human adults • microminerals are often referred to as trace elements Macrominerals Ca P S K Cl Na Mg calcium phosphorus sulfur potassium chloride sodium magnesium 1200 grams 860 grams 300 grams 180 grams 74 grams 64 grams 25 grams Microminerals F Zn Cu I Cr Co Si fluorine zinc copper iodine chromium cobalt silicon 2.6 V 2.0 Sn 0.1 Se 0.025 Mn 0.006 Ni 0.0015Mo 0.024 vanadium 0.018 tin 0.017 selenium 0.013 manganese 0.012 nickel 0.010 molybdenum 0.009 Other microminerals found in humans Sr (strontium) Br (bromine) Au (gold) Ag (silver) Al (aluminum) Bi (bismuth) As (arsenic) B (boron) the function of these minerals has not been established as of to date Scientific development which have contributed to trace element knowledge • design of highly purified and specially constituted diets • advances in analytical measurements • • • • • • colorimetruy fluorimetry flame photometry neutron activation analysis atomic absoption spectroscopy microwave excitation emission spectroscopy • isolation and study of metalloenzymes Functions of minerals • provide a suitable medium for cellular activity – permeability of membranes – irritability of muscles and nerve cells • play a primary role in osmotic phenomenon • involved in acid base-balance • confer rigidity and hardness to certain tissues (bones and teeth) • become part of specialized compounds Metalloenzymes • • • • • metal is firmly bound metal to protein ratio is constant metal to enzyme activity ratio is constant metal is unique no enzyme activity without metal Metalloenzymes Examples of metalloenzymes: – – – – – superoxide dismutase (Zn and Cu) carboxypeptidase A (Zn) carbonic anhydrase (Zn) cytochrome oxidase (Fe and Cu) xanthine oxidase (Co and Fe) Copper (Cu) • Deficiency – – – – decreased iron absorption neutropenia and leukopenia bone demineralization failure of erythropoiesis • sources • liver, shellfish, whole grains, cherries, legumes, nuts Fluorine • Considered essential because of its beneficial effect on tooth enamel • Benefits include: less dental caries, stronger bones, reduction in osteoporosis and calcification of the aorta • In large quantities it is deleterious to teeth; dental fluorosis: pitting, chalky, dull white patches and mottling of teeth • to parts per million is adequate for drinking water Iodine • iodine is necessary for the formation of thyroid hormones (T-4 and T-3) • deficiency of iodine is manifested by a goiter (enlargement of the thyroid gland) • salt water fish and seaweeds are a good source of iodine • to prevent the development of endemic goiter, tablet salt has been spiked with sodium iodide Fluorine • Main sources include drinking water and plants (spinach, lettuce, onions) • Average daily intake: 1.5 – 4.0 mg/day • Fluoride supplementation is available in both oral and topical forms: • Oral: mainly sodium fluoride (Pediaflor Drops) • Topical: either sodium or stannous fluoride (Fluorigard, Karigel, Fluoral) Silicon • essentiality has been established in chicks and rats, but not humans • appears to play an important role in the development and maintenance of cartilage (chondroitin sulfate, hyaluronic acid, keratin sulfate) • may have a protective role in cardiovascular diseases (atherosclerosis) • found in unrefined grains and beer Manganese • Maganese is an activator of several different enzymes: • • • • • • Phosphoglucomutase Isocitric dehydrogenase Cholinesterase Intestinal peptidase Carboxylases ATPases • However, magnesium and cobalt can replace Mn in several enzymes Manganese • Essential for sulfomucopolysaccharide biosynthesis • Deficiency leads to: • • • • Weight loss Transient dermatitis Nausea and vomiting Changes in hair color • Sources: blueberries, wheat bran, beet greens, lettuce, legumes, fruit • RDA: 2.5 – 5.0 mg Chromium • Cr III may act as a cofactor for insulin, enhancing glucose utilization • deficiency leads to impaired glucose tolerance (glucose tolerance factor) • sources: corn oil, whole-grain cereals, clams, drinking water (variable) • forms a coordination complex with micotinic acid and the amino acids glycine, glutamate and cysteine • chromium may have a role in type diabetes • RDA: 0.05 – 0.2 mg • frequently available in pharmacies as chromium picolinate Selenium • prevents: • • • • muscular dystrophy in lambs, calves and chicks liver necrosis in rats and pigs exudative diathesis in chicks and turkeys multiple necrotic degeneration of heart, liver, muscle and kidneys in mice • appears to function in the metalloenzyme glutathione peroxidase, which destroys peroxides in the cytosol • no deficiencies have been seen in humans • has antioxidant activity (may have relationship with vitamin E - sparing action) Tin • produces accelerated growth in deficient rats • tin is similar to carbon in its tendency to form covalent bonds • may have a role with heme-containing enzymes:heme oxygenase and cytochrome P-450 • largest quantities are found in kidneys and skin • human intake: ~ 1.5 - 3.5mg/day Cobalt • essentiality exists in some animals for ionic cobalt (sheep and cattle) • in rats administration of cobalt produces a polycythemia • cobalt in necessary in humans in the form of vitamin B12 • animals and plants cannot synthesize B12 • daily intake: 0.3 mg Vanadium • essentiality established in rats and chicks • human daily intake has been estimated at mg • plays a role in lipid metabolism (deficient chicks have a high plasma cholesterol and triglyceride levels) • may also function as an oxidationreduction catalyst Molybdenum • Widely found in commonly used foods (cereals, vegetables • Mo is part of flavoproteins, xanthine oxidase, aldehyde oxidase Sulfur • Most sulfur in the diet comes in from protein sources containing sulfur amino acids such as cysteine, cystine and methionine • Some enters as inorganic sulfur (sulfate, sulfide, chondroitin sulfate and certain other sulfate esters) • Sulfur is also present in thiamine, biotin, sulfolipids, conjugated bile acids and coenzyme A [...]... milk • absorption and metabolism: – readily absorbed – excreted in the urine and sweat – aldosterone increases reabsorption in remal tubules Sodium (Na) • RDA for adults: 1.1 to 3. 3 gm/day • sodium deficiency: – dehydration – acidosis – tissue atrophy • sodium excess: – edema (hypertonic expansion ) – hypertension Sodium (Na) • Sodium supplements: – usually used to replace sodium and chloride lost... aldosteronism severe vomiting and diarrhea cutaneous losses via perspiration – symptoms: • profound weakness of skeletal muscles (paralysis and impaired respiration • weakness of smooth muscles • cardiac anomalies: AV block, cardiac arrest Potassium • excess (hyperkalemia) – causes: • sudden increased intake • severe tissue trauma and burns • acute and chronic acidosis – symptoms: • weakness and paralysis • cardiac... pregnacy and lactation: 1200 mg/day Calcium supplements • • • • • • • calcium gluconate: calcium lactate calcium carbonate dibasic calcium phosphate calcium glucobionate calcium chloride calcium levulinate 9% 13% 40% 30 % 6% 27.2% 13% Phosphorus • required in many phases of metabolism • food sources: – – – – – phosphoproteins nucleoproteins nucleolipids glycerophosphates inorganic phosphates (Na and Ca)... phosphorylase kinase, salivary and pancreatic amylase) Calcium (Ca) • Calcium absorption: – variable due to insoluble salts: • phosphate • carbonate • oxalate • phytate • sulfate – also forms calcium soaps with fatty acids • absorption is enhanced by: • acid pH • vitamin D • lactose • lysine and glycine Calcium (Ca) • Excretion: – urine and feces – enhanced by lack of vitamin D and ingestion of large quantities... potassium, magnesium, carbonate and fluoride Calcium (Ca) • controlled by parathyroid hormone (PTH), calcitonin and vitamin D • maintained at a concentration of 5 mEq/L in plasma • about 1/2 is in the ionized form in serum • the other 1/2 is bound to protein (calcium citrate complex) Calcium (Ca) • function of calcium: – structural unit of bones and teeth – contraction and relaxation of muscles – stabilizes... sodium • excreted mainly in the kidneys (~ 2% in feces and ~ 4-5% in perspiration ) • important for osmotic balance, acid-base balance and in the formation of gastric HCl Chloride (Cl) • Deficiency of chloride: – – – – hypochloremic alkalosis hypovolemia pernicious vomiting psychomotor disturbances Calcium (Ca) • • • • the most abundant of the minerals the 5th most abundant element in the body needed... infusion (KCl and K acetate) Treatment of hyperkalemia • reverse cardiotoxic effects: – calcium gluconate IV • increase potassium uptake by cells: – dextrose (IV) – insulin (IV) – sodium bicarbonate (IV) • remove excess potassium from the body: – sodium polystyrene sulfonate (Kayexalate) Chloride (Cl) • an essential anion • closely connected with sodium in foods, body tissues and fluids and excretions... may exit without metal Metal-activated ezymes • Examples of metal-activated enzymes – creatine kinase (Mg, Mn, Ca or Co) – glycogen phosphorylase kinase (Ca) – salivary and pancreatic alpha-amylases (Ca) The electrolytes • There are 3 major electrolytes: – sodium – potassium – chloride Sodium (Na) • Sodium is the principal cation in extracellular fluids • functions include: • • • • • osmotic equilibrium... Heatrol Lytren solution Pedialyte solution Gatorade and other sports drinks Potassium (K) • Potassium is the principal cation in intracellular fluid • functions: – – – – – buffer constituent acid-base balance water balance membrane transport neuromuscular irritability Potassium • Food sources: vegetables, fruit (bananas), whole grains, meat, milk • absorption and metabolism: – readily absorbed (more so than... mineral content; 80% is structural – insoluble apatite in bone and teeth) • 20% is very active metabolically: • • • • • High energy phosphate compounds Nucleic acids Phospholipids Phosphoproteins Coenzymes (vitamins) Phosphorus • RDA for phosphorus is established on the basis of a 1:1 relationship with calcium – Adults: 800 mg/day – Pregnancy and lactation: 1200 mg/day • Phosphorus deficiency (hypophosphatemia)
- Xem thêm -

Xem thêm: minerals and mining 3 , minerals and mining 3 , minerals and mining 3

Gợi ý tài liệu liên quan cho bạn

Nạp tiền Tải lên
Đăng ký
Đăng nhập