Blood pH

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•  Chemoreceptors are sensitive to changes in blood pH

Aqueous carbon dioxide may combine with water in blood plasma to form carbonic acid (H2CO3)

  • Carbonic acid may then lose protons (H+) to form bicarbonate (HCO3) or carbonate (CO32–)
  • The released hydrogen ions will function to lower the pH of the solution, making the blood plasma less alkaline

Chemoreceptors are sensitive to changes in blood pH and can trigger body responses in order to maintain a balance

  • The lungs can regulate the amount of carbon dioxide in the bloodstream by changing the rate of ventilation
  • The kidneys can control the reabsorption of bicarbonate ions from the filtrate and clear any excess in the urine

Regulation of Blood pH

blood pH

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•  pH of blood is regulated to stay within the narrow range of 7.35 to 7.45

The pH of blood is required to stay within a very narrow tolerance range (7.35 – 7.45) in order to avoid the onset of disease 

  • This pH range is, in part, maintained by plasma proteins which act as buffers

A buffering solution resists changes to pH by removing excess H+ ions (↑ acidity) or OH ions (↑ alkalinity)

  • Amino acids are zwitterions – they may have both a positive and negative charge and hence can buffer changes in pH
  • The amine group may take on H+ ions while the carboxyl group may release H+ ions (which form water with OH ions)

Plasma Proteins Act as pH Buffers