Buffering system of blood pH

Buffer systems in the body function to maintain the blood at a steady and optimal pH of 7.40.

Our system maintains the blood’s pH balance using three regulatory mechanisms: bio-chemical buffering, respiratory regulation (removing carbon dioxide) and kidney regulation (excretion via urine): (1)

  1. Bio-chemical buffering – (the reaction to pH changes in the blood is immediate). Chemical buffers consist of extracellular and intracellular buffers (solutions located inside and outside cells) which prevent changes to the blood pH. These buffers react immediately to any acid-base changes in the blood. Bicarbonate is the most significant buffer which combines with the hydrogen ion (and reduces acidity). Bone also stores buffers and plays an important role by releasing calcium in case the blood becomes too acidic. It is not clear, however, at what pH level of the blood, bones release minerals for a buffering effect. Studies show that mineral bone release as a buffering mechanism is not due to any dietary factors, but rather more drastic blood pH changes associated with underlying medical conditions or medication/drug use. Nevertheless, more studies are needed. (read more..)
  2. Pulmonary regulation – buffering through breathing occurs over minutes to hours and is 50-75% effective in normalizing pH. Hydrogen ions (H+) in the body from acid food are neutralized by increasing the production of water and carbon dioxide which is the excreted through breathing. (2)
    The chemical formula for this is the following:
    H+ + HCO3- <-> H2CO3 <-> H2O + CO2
    The rate of breathing regulates the oxygen and carbon-dioxide ratio in our body and controls the blood’s pH. If, for instance, the blood pH drops (blood becomes more acidic), our brain will stimulate us to breath faster and deeper. This way more carbon dioxide is exhaled and the blood pH goes back to normal.
  3. Kidney regulation – (this action kicks in hours to days after changes in blood pH). The kidneys’ tubular system maintains acid-base balance by reabsorbing bicarbonate and secreting protons. This system allows the excess of acidic hydrogen ions in the body to be removed through urine. (2)
    The excess of acids in urine is often confused with body acidity. Urine becoming more acidic simply means that the kidneys buffering system works efficiently maintaining blood/body pH at a constant rate or within the very narrow safe range. (read more..)

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