haemoglobin

• haemoglobin is a quaternary protein made up of 4 polypeptide chains with a haem group
• haemoglobin has a high affinity for oxygen
• the process which haemoglobin binds with oxygen is called oxygen loading or oxygen associating
• the process which haemoglobin releases oxygen is called unloading or dissociation-this takes place in respiring tissues
• larger mammals (like elephant) have a higher affinity for oxygen as they have a low SA:VOL ratio and low metabolic rate per G, so doesn’t need to release as much oxygen
• The Bohr effect is when an increase in co2 levels pushes the line on the oxygen dissociation graph further right meaning more oxygen is release to respiring tissues
• in low partial pressure of oxygen haemoglobin has a low affinity for oxygen meaning that oxygen is more readily unloaded (to respiring body cells)
• in high partial pressure of oxygen, haemoglobin has a high affinity for oxygen meaning oxygen binds with it
• • When haemoglobin binds with one oxygen, it changes shape so it becomes easier to bind another oxygen.
  • When haemoglobin is mostly saturated with oxygen, it is harder for more oxygen to bind.
• fetal haemoglobin has a higher affinity to oxygen than adult haemoglobin because the fetus needs to obtain oxygen from mother's blood