bohr effect Flashcards
Why does oxygen load onto haemoglobin?
Because haemoglobin has a high affinity for oxygen due to the high concentration of oxygen/partial pressure of oxygen
Why does oxygen unload from haemoglobin at the tissues?
By the time it reaches the tissues where oxygen gets used for respiration, haemoglobin is going to have a lower affinity for oxygen because of the low concentration of oxygen.
This means that oxygen readily unloads from haemoglobin for use in respiration.
What does partial pressure of oxygen also stand for?
Concentration of oxygen
What are on the x and y axis of the oxyhemoglobin dissociation curve?
y = % saturation of haemoglobin
x= partial pressure of oxygen
What is the difference between tissues and lungs in terms of partial pressure of oxygen?
lungs have high partial pressure of 02
(haemoglobin is saturated with oxygen due to high affinity to oxygen in the lungs hence 02 loads)
tissue have low partial pressure of 02
(haemoglobin is less saturated with oxygen, haemoglobin has low affinity with oxygen so 02 unloads)
Why is the oxyhemoglobin dissociation curve s shaped?
- as we increase the partial pressure of oxygen, the % saturation of haemoglobin doesn’t increase that much
- but once we get a little higher, the % saturation of haemoglobin increases really quickly for a small increase in oxygen due to the cooperative nature of oxygen binding
- after the first oxygen molecule binds, the shape of haemoglobin changes in a way that makes It easier for the second and 3rd 02 molecule to bind too
- meaning haemoglobin has a higher affinity for oxygen so on the graph the gradient gets steeper (the rate of increase in % saturation increases as the 02 further increases)
- but after the haemoglobin starts to become more saturated, it gets harder for further molecules to bind too and this is why it plateaus
What causes the oxyhaemoglobin dissociation curve to shift to the right and why?
Carbon dioxide. (Bohr effect)
-because when we increase the co2 in our blood (e.g during exercise),
-This lowers the pH of our blood which also lowers the affinity of haemoglobin for oxygen due to haemoglobin changing shape, making it harder for molecules to bind
Why is the Bohr effect helpful?
Beneficial as it increases the amount of oxygen thats being unloaded from haemoglobin at the tissues and this oxygen is to be used in respiration
Why can organisms have different structures of haemoglobin?
They can be adapted depending on the environment the organism is in. Haemoglobin is a protein made of amino acids and when these amino acids get changed, haemoglobin can have a different structure as primary structure changes resulting in it folding in a slightly different way.
Its changed shape can affect its affinity for oxygen which may cause the oxygen dissociation curve to shift to left or right.
Organisms can be adapted to their environment by having different types of haemoglobin with different oxygen transport properties (increases survival)
What does it mean when the oxygen dissociation curve shifts to the left?
Haemoglobin has a higher affinity for oxygen meaning that it loads more readily in the lungs at a lower oxygen concentration.
Main adv is that we don’t need to worry about the effect on the tissues.
This is particularly useful of organisms in low 02 environments because they can load more 02 in the lung e.g fatal haemoglobin compared to adult haemoglobin
What does It mean when the oxygen dissociation curve shifts to the right?
Haemoglobin has a lower affinity for 02 (don’t need to worry about the effect of this in the lungs, its going to be beneficial for our tissues)
At the same partial pressure of 02 as tissue our haemoglobin again has a lower saturation of oxygen meaning more has been unloaded to the tissues (similar to Bohr effect)
This is important to organisms that need more 02 in their tissues
