Mineral metabolism

• Mineral


  A naturally occurring inorganic element or compound having an orderly internal structure and characteristic chemical composition, crystal form, and physical properties
• Minerals classified into


  • Principal elements
  • Trace elements
• Principal elements


  • Na
  • K
  • Ca
  • Mg
  • P
  • S
  • Cl
  • Fe
• Trace elements


  • Cu
  • Co
  • I
  • Mn
  • F
  • Mo
  • Se
  • Al
  • Zn
  • Cr
• Calcium


  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
• Importance of Calcium


  • Essential for formation of bone and teeth
  • Necessary for muscle contraction
  • Plays an important role in the transmission of nerve impulses
  • Activation of certain enzymes
• About 30% of dietary calcium is absorbed
• Factors affecting absorption of Calcium

  • Concentration of calcium in diet
  • pH
  • Amount of magnesium in diet
  • Amount of proteins in diet
  • Vitamin D
  • Parathormone
• Calcium Blood Level


  Plasma normally contains 9 – 11 mg / 100 ml of calcium
• Classification of diffusible calcium

  • Ionisable
  • Non-ionisable
• Factors affecting plasma calcium level

  • Vitamin D
  • Parathyroid hormone
  • Calcitonin
  • Plasma phosphate
  • Plasma proteins
• Sources of Calcium


  • Cheese and milk
  • Fruits
  • Vegetables
  • Egg yolk
  • Legumes
• Requirements for Calcium


  • For normal adults: 0.8 g/day
  • For pregnant and lactating women: 1.2 g/day
• Excretion of Calcium


  • In feces: 80%
  • In urine: 20%
• Phosphorus


  Total body phosphorus is about 800 g
• 80% of phosphorus is in the skeleton and 20% in other tissues and body fluids
• Importance of Phosphorus


  • Formation of bones and teeth
  • Formation of nucleic acids and nucleotides
  • Formation of phospholipids
  • Formation of many coenzymes
  • Formation of buffers
• Only about 70% of food phosphates are absorbed
• Factors affecting plasma inorganic phosphate

  • Renal function
  • Parathyroid hormone
  • Vitamin D
• Sources of Phosphorus


  • Cheese
  • Milk
  • Liver
  • Kidney
  • Heart
  • Meats
  • Fishes
• Requirements for Phosphorus


  • For normal adults: 0.8 – 1 g/day
  • For pregnant and lactating women: 1.2 g/day
• Excretion of Phosphorus


  • In urine: 60%
  • In feces: 40%
• Magnesium


  Total body magnesium is about 21 g
• 70% of magnesium is in the skeleton and 30% in other tissues and body fluids, mostly intracellular
• Importance of Magnesium


  • Normal contraction of muscles
  • Formation of bones and teeth
  • Normal transmission of nerve impulses
  • Activation of kinases, phosphorylases and transketolases
• About 40% of the ingested magnesium is absorbed
• Sources of Magnesium


  • Vegetables
  • Legumes
  • Meats
  • Fish
  • Liver
  • Kidney
  • Heart
• Requirements for Magnesium


  • For normal adults: 0.3 g/day
• Excretion of Magnesium


  • In feces: 70%
  • In urine: 30%
• 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
• 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
• Sources of Sodium, Potassium and Chloride


  • Table salt
  • Potatoes
  • Fruits
  • Meats
  • Fishes
  • Vegetables
  • Legumes
• Requirements for Sodium, Potassium and Chloride

  • For normal adults: 10 – 15 g/day NaCl
  • 3 – 5 g/day KCl
• Excretion of Sodium, Potassium and Chloride

  • Excretion is mainly controlled by aldosterone hormone
  • 95% in urine
  • Small amounts in feces and sweat
• Sulphur


  Sulphur containing compounds in the body are classified into inorganic and organic compounds
• Sources of Sulphur


  • Attained by adequate proteins in the diet
• Excretion of Sulphur


  • Mainly through urine and feces
  • Other routes include hairs, nails and skin
• Iron


  Total body iron is about 4 g