Transport of Oxygen 2

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Transport of Oxygen 2

• The Bohr effect
• Fetal haemoglobin
• Myoglobin

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Transport of Oxygen 2

• Hb is even more efficient that suggested by the
  dissociation curve
• The amount of O2 carried by Hb depends not only
  on the p O2 but also the partial pressure of
  carbon dioxide.

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Transport of Oxygen 2

• At the tissues there is high carbon dioxide
  this reduces Hb affinity for oxygen so it gives
  it up.
• Conversely at lungs there is low carbon dioxide
  so the Hb has a greater affinity for oxygen so
  picks up more.

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Transport of Oxygen 2

• The result is thus, that under the same blood pO2
  conditions, high levels of CO2 (acidic
  conditions) will unload more O2 from the Hb
• Oxyhaemoglobin releases its oxygen where it is
  most needed to the actively respiring tissues.

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Transport of Oxygen 2

• The further the dissociation curve moves to the
  right, the more readily Hb gives up its oxygen.

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Transport of Oxygen 2

• The further the dissociation curve moves to the
  left, the more readily Hb picks up oxygen.

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Fetal haemoglobin

• The developing fetus obtains oxygen from its mum
• Fetal and maternal blood run close together but
  never mix
• This allows materials to diffuse from the blood
  of mum into the fetus and vice versa..

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Fetal haemoglobin
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Fetal haemoglobin

• The dissociation curve of fetal Hb is to the left
  of adult Hb
• This means fetal Hb combines with oxygen more
  readily than adult Hb
• Fetal Hb has a higher affinity for oxygen.

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Fetal haemoglobin

• At the placenta the fetal haemoglobin can steal
  oxygen form the maternal haemoglobin.

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Myoglobin

• In muscle there is another oxygen binding
  molecule called myoglobin.
• Oxymyoglobin is much more stable than
  oxyhaemoglobin

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Myoglobin

• Myoglobin will only give up its oxygen at very
  low oxygen partial pressures.

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Myoglobin

• The myoglobin dissociation curve is a long way to
  the left of Hb.
• At each partial pressure of oxygen, myoglobin
  holds onto much more oxygen than Hb.

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Myoglobin

• This enables myoglobin to act as an oxygen store.
• Usually respiring muscle will get its oxygen from
  oxyhaemoglobin
• Only if the partial pressure of oxygen falls very
  low will oxymyoglobin release its oxygen