mass transport

• higher partial pressure of oxygen - haemoglobin has a high affinity for oxygen and binds with it.
• lower partial pressure of oxygen - haemoglobin has a low affinity for oxygen and releases it.
• the cooperative nature of oxygen binding -

  1. when haemoglobin binds with one oxygen, it changes shape so it becomes easier to bind to another oxygen.
  2. when haemoglobin is mostly saturated with oxygen, it is harder for more oxygen to bind.
• fetal haemoglobin -

  1. the foetus needs to obtain oxygen from the mother's blood.
  2. the fetal haemoglobin therefore has a higher oxygen affinity than the adult haemoglobin found in the mother's blood.
  3. this allows the oxygen to dissociate from the mother's haemoglobin, and bind with the haemoglobin in the fetal blood.
  4. this ensures that the fetus gets enough oxygen to survive while it develops.
• the Bohr effect - haemoglobin has a lower affinity for oxygen at higher partial pressures of carbon dioxide.
• the Bohr effect shifts the oxygen dissociation curve to the right.