4.3.3 - Transporting carbon dioxide and oxygen Flashcards
Describe the structure of haemoglobin.
Made up of 4 polypeptide chains each with a haem group.
2 Alpha glucose chains. 2 Beta glucose chains.
What is haemoglobin known as when it’s oxygenated?
Oxyhaemoglobin
Role of haemoglobin.
Readily associates with oxygen in the lungs.
Readily dissociates with oxygen at respiring tissues.
Why is it easier for oxygen molecules to associate with haemoglobin after the first one is loaded?
The haemoglobin changes shape.
Why does it become more difficult for the 4th oxygen molecule to load?
Less chance - only one more oxygen molecule can load onto that haemoglobin molecule.
Where does the loading and unloading of oxygen occur?
Loading - The lungs
Unloading - Respiring tissues
What is the affinity of haemoglobin?
The chemical attraction of haemoglobin towards oxygen.
What does a high affinity of haemoglobin mean?
Takes up oxygen easily, releases less easily.
What is partial pressure?
The pressure exerted by a gas (the concentration)
In the graph showing the relationship between saturation of haemoglobin with oxygen and pp, why is the graph shallow at first?
The shape of haemoglobin makes it difficult for oxygen to load.
In the graph showing the relationship between saturation of haemoglobin with oxygen and pp, why does the graph get steeper in the middle?
The haemoglobin molecule changes shape after the first oxygen molecule binds making it easier for other oxygen molecules to bind.
In the graph showing the relationship between saturation of haemoglobin with oxygen and pp, why does the graph plateau?
Most binding sites are occupied so more unlikely for an oxygen molecule to find an empty binding site.
Describe how oxygen is transported, loaded and unloaded in the blood.
Haemoglobin carries oxygen
In red blood cells
Loading of O2 takes place in lungs
At a high PO2
Unloads at respiring tissues
At a low PO2
Unload at a higher C02 concentration.
What does a further left curve mean?
A greater affinity of haemoglobin for oxygen.
What happens to the affinity of haemoglobin for oxygen at high PCO2?
It is reduced, enables more oxygen to be unloaded at respiring tissues.
Which way will the graph shift if carbon dioxide concentration is increased?
Shift right.
What is the Bohr effect?
The greater the concentration of carbon dioxide, the more readily haemoglobin unloads oxygen.
Features of fetal haemoglobin.
Higher affinity for oxygen at the same PO2 as adult Hb.
Loads at a PO2 which adult Hb deloads.
Features of myglobin
Higher affinity for O2 than fetal Hb
Stores O2 in muscle
Only unloads when oxygen concentration is very low.
Found in human muscles.
Is the fetal Hb curve to the left or right of the adult Hb curve?
Left - greater affinity
Is the myoglobin curve to the left or right of the adult Hb curve?
Left
