First 434 words of the document:
1. Haemoglobin is a quaternary protein molecule.
It's made of 4 polypeptide chains and each chain has a haem group which can
bind to a molecule of oxygen.
So a haemoglobin molecule can bind to 4 molecules of oxygen and that means it
has a high affinity for oxygen as it can hold on to more oxygen.
Oxygen is loaded onto the haemoglobin in the lungs (where the pO2 is high), and
unloaded in the body (where the pO2 is low).
2. People living in the Andes South America have a higher concentration of
haemoglobin in their blood so more oxygen can be carried in the same
volume of blood.
Tibetans have doubled their nitric oxide levels. Nitric oxide dilates the blood
vessels, to allow increase blood circulation and therefore more oxygen can get to
the rest of the body.
They also have less haemoglobin in their blood because having too much
haemoglobin might cause the blood to be viscous so it makes it harder to the heart
to pump blood around the body. It hinders oxygen, nutrients and hormones
circulation and might cause illnesses like "hypoxia" (where you have low levels of
oxygen, therefore makes respiration less efficient).
They also take more breaths per minute to increase oxygen intake.
3. The foetus respires, so it has a low pO2, so some oxygen will unload from the
mother's blood onto the foetus' haemoglobin. However, the concentration
gradient is not big enough, so they have different haemoglobins.
The oxygen is transferred across the placenta.
The mother uses up the oxygen, so the oxygen saturation will have
decreased by the time it reaches the foetus.
Foetal haemoglobin has a higher affinity for oxygen than its mother's blood so it
can load oxygen more readily, so it's better at absorbing oxygen.
4. The haemoglobin in llamas have higher affinity for oxygen, so at a low pO2,
its haemoglobins are saturated with oxygen.
The haemoglobin in pigeons have lower affinity for oxygen, so it unloads oxygen
more readily because pigeons are respiring all the time, it needs oxygen more
quickly. The partial pressure of CO2 increases in the pigeon due to respiration, so it
decreases the pO2, and shifts the oxygen dissociation curve to the right.
When carbon dioxide is present, the shape of haemoglobin changes slightly. This
change means that oxygen binds more loosely so the oxygen is released.