Minerals
• Sodium :
• Potassium :
• Calcium :
• Sodium :
• Sodium (NA+) is the major extracellular cation
• Normal serum sodium level is 135-145 mEq/L
• Na+ is a freely filtered glomeruli. The filtered sodium is reabsorbed by :
• Proximal tubules – 70%
• Loop of Henle – 15%
• Distal convolumed tubule – 5%
• Collecting duct – 10%
• Functions of sodium:
• Fluid and electrolyte balance.
• Plays a major role in the maintenance of osmotic pressure of body fluids
• Regulation of acid base balance
• Maintenance of neuromuscular irritability and excitability (never transmission).
• Maintenance of blood viscosity
• Helps in absorption of monosaccharide and amino acids.
• Daily requirement (as sodium chloride) is 5-15 g
• Sources : Main source is common salt. Meat, seafood, milk and cheese are also good sources of sodium.
• Potassium :
• Potassium (K+) is the chief intracellular cation
• Maintenance of the normal level of K+ is essential for life.
• Normal serum potassium level is 3.5 – 5.2mEq/L
• Functions :
• Water and electrolyte balance
• Maintenance of neuromuscular irritability and excitability
• Storage of glycogen and cell protein requires K+
• Regulation of pH body fluids
• Recommended Daily Requirement of Potassium for an adult is 4g.
• Source: Most of the vegetables (e.g, potato tomato), daily products, coffee, cocoa, dried, beans, wheat bran, eggs, meat, and b fruits ( bnana, peach, orange).
• Calcium :
• Calcium (Ca) is found in the highest concentration in the body
• An adult man contains nearly 1.0-1.2 kg of calcium ( 99% of it is present in skeletal tissue)
• Normal serum calcium level is 9-11 mg/dl
• Calcium absorption
• Calcium is absorbed by all parts of the small intestine. Most rapid absorption occurs in the acidic medium (duodenum) compared to alkaline medium (remaining part of small intestines).
• Calcium absorption is impaired in vitamin D deficiency
• Excess of phosphate reduces calcium absorption.
• Regulation of serum calcium
• Vitamin D increases serum Calcium by promoting intestinal absorption
• Parathyroid (PTH) hormone plays a vital role in regulation of Ca2+. Low serum calcium leads to increase in the PTH secretion. PTH acts on osteoclasts and promotes transfer of calcium from bone tissues of the blood (known as bone resorption)
• Calcitonin lowers serum calcium by promoting deposition of calcium by osteoblasts (opposite to PPH action)
• PTH increases reabsorption of calcium by the kidneys
• Functions
• Calcification of growing bones are teeth
• Maintenance of Mature bone
• Calcium is essential for blood clotting
• Role in the citric acid cycle and glycogen break down.
• Activator several enzymes
• Required for contraction of muscles
• Decrease in blood calcium level may result in tetany (abnormal muscle spasm)
• Deficiency of calcium results in rickets in children and osteomalacia in adults
• Recommended daily requirements is 800 mg for an adult; 1.2/day during pregnancy.
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Writer: Vandita Singh, Lucknow