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pH

  • Potentiality of Hydrogen ion concentration or power of Hydrogen ion.
  • pH is defined as –log of Hydrogen ion concentration.
  • Defined by Sorenson
  • pH=-log[H+]
  • Significance of pH
  • Digestion of food
  • Activity of enzymes
  • Maintaining the blood pH for homeostasis

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Henderson Hasselbalch equation

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Types of buffer

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  • Buffer action
  • The capacity(magnitude) of buffer solution that tends to resist the changes in pH by one unit when small amount of acid or base is added.

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Protein buffer

  • In acidic medium protein acts as base and accept the proton from the medium. Proteins get positive charge.
  • In basic medium protein acts as acid and donate the proton to the medium. Proteins get negative charge.

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Hb buffer

  • Buffering capacity of Hb is due to imidazole ring of Histidine. Each Hb contains 38 Histidine molecule.
  • Hb contains Fe++ containing group(where oxygen) binds and imidazole nitrogen group(which can donate or accept the proton).
    • Oxygenation: acts as acid and donate the proton.(lungs)
    • Deoxygenation: acts as base and accept the proton from medium.(tissues)

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