The Bohr effect

The Bohr effect

1. It describes the effect that an increasing concentration of carbon dioxide has on the haemoglobin. (in respiring tissues)

   • ~carbon dioxide enters the RBC forming carbonic acid, which dissociates to release hydrogen ions.
     • ~these hydrogen ions affect the pH of the cytoplasm, making it more acidic
       • ~changes in pH can affect the tertiary structure of the Hb =increase acidity reduces the affinity of Hb for O2.
         • =Hb unable to hold as much O2, & O2 is released from the oxyhaemoglobin to tissues

2. CO2 lowers the affinity of Hb for O2. O2 will dissociate more easily.

   • With a higher pCO2 the oxygen association/dissociation curve moves to the right. This is because CO2 increases the dissociation of oxyhaemoglobin to O2 + Hb

3. So in tissues where respiration is taking place (muscles), CO2 is produced. =CO2 transport to occur & H+ to bind to Hb to make haemoglobonic acid.

   • This process results in O2 being released, & less O2 being able to associate
     • So, when more CO2 is present, Hb becomes less saturated with O2 = change in curve (RIGHT & DOWNWARDS) =Bohr shift.
       • This Bohr effect = more O2 release where more CO2 is produced in respiration ~just what the muscles need for aerobic respiration to continue.