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Mineral metabolism

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Mineral metabolism A) Principal elements 6) Iron Sources Animal sources: Liver, kidney, spleen, heart, red meats and egg yolk. Plant sources: Dates, legumes ... – PowerPoint PPT presentation

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Title: Mineral metabolism


1
Mineral metabolism
2
  • Minerals are classified into
  • Principal elements which exist in the body in
    large amounts. e.g. Na, K, Ca, Mg, P, S, Cl and
    Fe.
  • Trace elements which exist in the body in small
    amounts.
    e.g. Cu, Co, I2, Mn, F, Mo, Se, Al, Zn and Cr.

3
A) Principal elements1) Calcium
  • Calcium is present in the body in larger amounts
    than any other cation.
  • The amount of calcium in the body of adults is
    about 1400 g.
  • 99 of the body calcium is in the skeleton (bones
    and teeth) and the other 1 is present in other
    tissues and body fluids.

4
A) Principal elements1) Calcium
  • Importance of Calcium
  • Essential for formation of bone and teeth.
  • Necessary for muscle contraction.
  • It plays an important role in the
    transmission of nerve impulses.
  • Activation of certain enzymes.

5
A) Principal elements1) Calcium
  • Absorption of Calcium
  • About 30 of dietary calcium is absorbed.
  • Absorption of calcium is affected by the
    following factors
  • Concentration of calcium in diet The higher the
    concentration, the more the absorption of
    calcium.
  • pH Calcium salts are soluble in acid solutions,
    so, acidity increases the absorption.

6
A) Principal elements1) Calcium
  • Absorption of Calcium
  • Requirements of the body.
  • CaP ratio The optimum ratio for absorption of
    both elements is about 11 or 12
  • Amount of magnesium in diet Excess magnesium in
    diet inhibits calcium absorption as magnesium
    competes with calcium for absorption.

7
A) Principal elements1) Calcium
  • Absorption of Calcium
  • Amount of proteins in diet Amino acids form
    soluble complexes with calcium, so, high protein
    diet favors the absorption of calcium.
  • Vitamin D 1,25 dihydroxy vit. D induces the
    formation of a carrier protein that is important
    for the transfer of calcium across the intestinal
    mucosal epithelium.
  • Parathormone Involved in the conversion of Vit.
    D to 1,25 dihydroxy vit. D, so, it helps calcium
    absorption.

8
A) Principal elements1) Calcium
  • Calcium Blood Level
  • Plasma normally contains 9 11 mg / 100 ml of
    calcium. 45 of which is non-diffusible )bound to
    plasma albumin).
  • The diffusible calcium (55) is classified into
  • Ionisable (50) active form.
  • Non-ionisable (5) Calcium citrate.
  • Erythrocytes almost contain no calcium.

9
A) Principal elements1) Calcium
  • Factors affecting plasma calcium level
  • Vitamin D It increases calcium level as
  • It increases absorption of calcium from the
    intestine.
  • It increases reabsorption of calcium by renal
    tubules.
  • Parathyroid hormone (parathormone) It increases
    calcium level by increasing
  • Absorption of calcium from the intestine.
  • Reabsorption of calcium by renal tubules.
  • Mobilization of calcium from bones.

10
A) Principal elements1) Calcium
  • Factors affecting plasma calcium level
  • Calcitonin (secreted by the thyroid gland) It
    lowers calcium blood level by inhibiting
    mobilization of calcium from bones.
  • Plasma phosphate Increase of plasma phosphates
    leads to a decrease of plasma calcium and vice
    versa.
  • Plasma proteins Decrease in plasma proteins ?
    decrease of the non-diffusible form of calcium ?
    decrease of total plasma calcium.

11
A) Principal elements1) Calcium
  • Sources
  • Cheese and milk (rich sources).
  • Fruits, vegetables, egg yolk and legumes (small
    amounts).
  • Requirements
  • For normal adults 0.8 g/day.
  • For pregnant and lactating women 1.2 g/day.
  • Excretion
  • In feces 80
  • In urine 20

12
A) Principal elements2) Phosphorus
  • Total body phosphorus is about 800 g.
  • 80 in the skeleton and 20 in other tissues and
    body fluids.
  • Phosphorus is present in every cell of the body.

13
A) Principal elements2) Phosphorus
  • Importance of Phosphorus
  • Formation of bones and teeth.
  • Formation of nucleic acids and nucleotides. e.g.
    ATP, ADP and cAMP.
  • Formation of phospholipids, phosphoproteins,
    hexose, pentose and triose phosphates.
  • Formation of many coenzymes as TPP, CoA-SH, NAD,
    NADP, FMN, FAD, UDP-G and pyridoxal phosphate.
  • Formation of buffers.

14
A) Principal elements2) Phosphorus
  • Absorption of Phosphorus
  • Phosphorus is absorbed from the intestine in the
    form of phosphates.
  • Only about 70 of food phosphates are absorbed.
  • Factors which help the absorption of calcium will
    secondarily help the absorption of phosphate as
    unabsorbed calcium inhibits the absorption of
    phosphate.
  • The best Ca/P ratio for the proper absorption of
    both calcium and phosphate is 11 (12 to 21).

15
A) Principal elements2) Phosphorus
  • Blood Phosphorus
  • In plasma
  • Inorganic phosphates 3.5 mg/100 ml.
  • Organic phosphates mostly phospholipids.

16
A) Principal elements2) Phosphorus
  • Factors affecting plasma inorganic phosphate
  • Renal function Renal failure ? failure of
    excretion in urine ? ? plasma inorganic
    phosphate.
  • Parathyroid hormone It inhibits renal tubular
    reabsorption of phosphate ? ? phosphate excretion
    in urine ? ? plasma phosphate.
  • Vitamin D Plasma inorganic phosphate decreases
    in rickets.

17
A) Principal elements2) Phosphorus
  • Blood Phosphorus
  • In RBCs
  • Inorganic phosphates Potassium monohydrogen
    phosphate K2HPO4 and potassium dihydrogen
    phosphate KH2PO4.
  • Organic phosphates mainly in the form of hexose,
    pentose, triose phosphates and ATP.

18
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19
A) Principal elements2) Phosphorus
  • Sources
  • Cheese, milk, liver, kidney, heart, meats and
    fishes.
  • Requirements
  • For normal adults 0.8 1 g/day.
  • For pregnant and lactating women 1.2 g/day.
  • Excretion
  • In urine 60
  • In feces 40

20
Principal elements 3) Magnesium
  • The total body magnesium is about 21 g.
  • 70 in the skeleton and 30 in the other tissues
    and body fluids, mostly intracellular.
  • Magnesium in muscle cells is about 10 times that
    in plasma.

21
A) Principal elements3) Magnesium
  • Importance of Magnesium
  • Magnesium is important for
  • Normal contraction of muscles.
  • Formation of bones and teeth.
  • Normal transmission of nerve impulses.
  • Activation of kinases, phosphorylases and
    transketolases.

22
A) Principal elements3) Magnesium
  • Absorption of Magnesium
  • About 40 of the ingested magnesium is absorbed.
  • Factors affecting absorption of magnesium are the
    same affecting calcium absorption.

23
A) Principal elements3) Magnesium
  • Blood Magnesium
  • Plasma magnesium is normally 2.2 mg/ 100 ml.
  • Magnesium in RBCs is about 2 3 times its amount
    in plasma.

24
A) Principal elements3) Magnesium
  • Factors affecting plasma magnesium
  • Renal function Renal failure ? ? excretion of
    magnesium ? hypermagnesemia.
  • Aldosterone ? ? renal clearance ? ? plasma
    magnesium.
  • Parathyroid hormone ? ? mobilization of magnesium
    from bones ? ? magnesium in blood.

25
A) Principal elements3) Magnesium
  • Sources
  • Vegetables (chlorophyll), legumes, meats, fish,
    liver, kidney and heart.
  • Requirement
  • For normal adults 0.3 g/day.
  • Excretion
  • In feces 70
  • In urine 30

26
A) Principal elements 4) Sodium,
Potassium and Chloride
  • One third of the total sodium, potassium and
    chloride content of the body is present in the
    skeleton. The remaining two thirds are present in
    other tissues and body fluids.
  • Sodium and chloride are chiefly extracellular
    and potassium is chiefly intracellular.

27
A) Principal elements 4) Sodium,
Potassium andChloride
  • Importance of Sodium, Potassium and Chloride
  • Maintenance of fluid volumes and osmotic
    pressure.
  • Formation of buffers.
  • Transmission of nerve impulses.
  • Contraction of muscles.
  • Chloride activates amylase enzyme.
  • Chloride is important for formation of gastric
    HCl.

28
A) Principal elements 4) Sodium,
Potassium and Chloride
  • Sources of Sodium, Potassium and Chloride
  • Table salt (NaCl).
  • Potassium is present in potatoes, fruits, meats,
    fishes, vegetables and legumes.

29
A) Principal elements 4) Sodium,
Potassium and Chloride
  • Requirements for normal adults
  • 10 15 g/day NaCl
  • 3 5 g/day KCl
  • Excretion
  • Excretion is mainly controlled by aldosterone
    hormone.
  • 95 in urine.
  • Small amounts in feces and sweat.

30
A) Principal elements5) Sulphur
  • Sulphur containing compounds in the body are
    classified into
  • Inorganic compounds Sulphate, thiosulphate and
    tiocyanate.
  • Organic compounds
  • Amino acids Cysteine, cystine, methionine and
    homocysteine.
  • Proteins Keratin, hormones (insulin, parathyroid
    hormone, ACTH and MSH).
  • Vitamins Thiamine, Biotin and Lipoic acid.
  • Other compounds e.g. CoA-SH, glutathione,
    ergothionine, heparin, adenosine and urochrome.

31
A) Principal elements5) Sulphur
  • N.B.) Ergothionine and glutathione are present in
    RBCs.
  • Requirements of sulphur are attained by adequate
    proteins in the diet.
  • Excretion of sulphur is mainly through urine and
    feces.
  • Other routes of excretion include hairs, nails
    and skin.

32
A) Principal elements6) Iron
  • The total body iron is about 4 g.
  • Iron is present in the following compounds
  • Hemoglobin (70 of iron).
  • Myoglobin (5 of iron).
  • Respiratory enzymes (5) Cytochrome a, b and c,
    catalase and peroxidase.
  • Transferrin and ferritin.
  • Hemosederin.

33
A) Principal elements6) Iron
  • Absorption of Iron
  • Iron is only absorbed in an inorganic form.
  • Ferric (Fe3) must be converted to ferrous (Fe2)
    before absorption. This is helped by reducing
    substances in food as cysteine and vitamin C.
  • In the plasma ferrous is oxidized rapidly to the
    ferric state to be carried by transferrin.
    Oxidation is catalyzed by ceruloplasmin (a
    copper-containing protein).

34
A) Principal elements6) Iron
  • Sources
  • Animal sources Liver, kidney, spleen, heart, red
    meats and egg yolk.
  • Plant sources Dates, legumes, vegetables and
    cereals.
  • Requirements
  • For normal adults 10 15 mg/day.
  • For pregnant and lactating women 20 mg/day.

35
A) Principal elements6) Iron
  • Excretion
  • Iron is never excreted in urine as it is carried
    on a ß-globulin. (Proteins are not passed through
    the glomeruli).
  • In feces 90 95
  • In sweat 5
  • In menstruation and milk 5

36
B) Trace elements1) Copper
  • Copper is present in most tissues such as liver,
    muscles, bones.etc.
  • Liver is the storage site for copper.
  • The total body copper normally ranges between 100
    and 150 mg.

37
B) Trace elements1) Copper
  • Importance of Copper
  • Hemopoiesis Copper helps the absorption of iron
    from the intestine and helps mobilization of iron
    from its stores.
  • Copper is an essential component of cytochrome
    oxidase and superoxide dismutase.
  • It is important for the formation of myelin
    sheath.
  • Hemocyanin is a cupro-protein which function as
    an oxygen carrier in the blood of some
    invertebrates (instead of hemoglobin).

38
B) Trace elements1) Copper
  • Blood Copper
  • Copper is present in plasma bound to a globulin
    fraction forming ceruloplasmin.
  • Copper is also present in RBCs in the form of
    erythrocuprein.

39
B) Trace elements1) Copper
  • Wilsons Disease
  • It is a congenital disease characterized by
  • Low plasma ceruloplasmin.
  • Increased copper bound to albumin.
  • Accumulation of large amounts of copper in the
    liver ? liver cirrhosis.
  • Accumulation of large amiunts of copper in brain
    ? parkinsonism.
  • Excretion
  • Copper is excreted mainly in feces.

40
B) Trace elements2) Iodine
  • The total body iodine is 25 50 mg.
  • Iodine is present in
  • Thyroid gland (30).
  • Other tissues and body fluids (70).
  • Functions
  • Iodine enters in the formation of thyroid
    hormones.

41
B) Trace elements2) Iodine
  • Sources
  • Sea water, sea fishes, see weeds, vegetables and
    fruits grown on the sea board are rich sources of
    iodine.
  • Absorption
  • Iodine and sodium iodide are readily absorbed
    from the skin, lungs and intestine.
  • Excretion
  • Urine 70 Feces 30
  • Small amounts are excreted through sweat, lungs
    and milk.

42
B) Trace elements3) Manganese
  • Manganese is important for
  • Growth.
  • Normal bone structure.
  • Normal functions of CNS.
  • Spermatogenesis and ovulation.
  • Manganese is an essential component of some
    enzymes such as arginase, cholinesterase,
    carboxylases and some decarboxylases.

43
B) Trace elements4) Zinc
  • Zinc is important for
  • Normal taste and appetite.
  • Normal growth and healing of wounds.
  • Development of gonads.
  • Mobilization of vitamin A from its stores.
  • Zinc acts as a component of insulin and some
    enzymes such as carbonic anhydrase and
    carboxypeptidase.
  • Deficiency of zinc causes testicular degeneration
    by the testicular proteolytic enzyme which is
    normally inhibited by zinc.

44
B) Trace elements5) Flourine
  • Flourine is present in many tissues such as
    bones, teeth, thyroid gland and skin.
  • Flourine is absorbed from intestine and excreted
    in urine, milk and sweat.
  • Intake of 1 1.5 part per million of flourine in
    the drinking water increases resistance of teeth
    to dental caries due to
  • Formation of flouroapatite in teeth.
  • Inhibition of fermentation of carbohydrates by
    the oral bacteria because flouride inhibits
    enolase enzyme.

45
B) Trace elements 5) Flourine
  • Excess flourine leads to flourosis which is
    characterized by
  • Teeth become brittle and mottled with whitish
    patches.
  • Bones become denser with calcification at the
    point if insertion of muscles.

46
B) Trace elements6) Chromium
  • Chromium is essential for
  • Proper utilization of glucose by tissues.
  • Normal growth.

47
B) Trace elements7) Cobalt
  • Cobalt is important for formation of vitamin B12
    which is important in hemopoiesis.
  • Over administration of cobalt leads to
    polycythemia.

48
B) Trace elements8) Selenium
  • Selenium is a component of the enzyme glutathione
    peroxidase which protects hemoglobin,
    polyunsaturated fatty acids and cell membranes
    against oxidative damage by H2O2

49
B) Trace elements9) Molybdenum
  • Molybdenum is an essential component of some
    flavoprotein enzymes such as Sulphite oxidase,
    aldehyde oxidase and xanthine oxidase.
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