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Acid-Base Homeostasis In The Body

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The maintenance of a stable H+ concentration in all body fluids is essential for life. The H+ concentration, or pH is always maintained such that enzymatic activity and protein structure are at maximum efficiency

{pH is the negative log of H+ concentration, pH = -log10[H+]}

  • The disruption of this balance could cause severe complications.
  • For example, acidaemia is a condition where the arterial blood pH drops below 7.36 while alkalaemia means the arterial blood pH has increased than 7.45

{survival range is 6.8 to 8.0 pH}

  • If no secondary changes occur to bring the pH back to normal, this will result in acidosis or alkalosis
  • Effects of low pH in arterial blood
    • Hyperkalaemia where excess K+ ions are released in the renal flow
    • Drop in arterial BP due to loss in smooth muscle tone
    • Osteoporosis as a result of mineral loss from bones
  • Effects of high pH in arterial blood
    • Tetany, numbness of extremities
    • Drop of Ca2+ in ECF
    • Nerve fibers easily getting excited
  • H+ balance in the body is maintained by numerous systems
Input (nm/day) Output (nm/day)
Metabolic CO2 13000 Lungs 13000
Lactate 1500 Liver, Kidney 21500
Protein, SO4, PO4 45 Titratable acids 30
Phospholipid metabolism 13 NH4+ 40
Other 12


Acid base balance in the body is controlled in three main ways

1) Buffering – Happens in minutes
2) Respiratory regulation – Happens over hours
3) Renal regulation – Happens over days

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Categorised in: Biochemistry, Medicine, Physiology

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