ODC Flashcards
what is another name for the oxygen dissociation curve?
explain what it’s position means
- S shaped curve/ sigmoidal curve
-the further to the left the curve is the higher the affinity of haemoglobin for oxygen
-the further right the curve is the lower the affinity of the Hb for oxygen
explain what 4kPa (pO2) is on the oxygen dissociation curve
-25% saturation of haemoglobin with oxygen
- low pO2 high pCO2 so O2 is released
-at actively respiring tissue ~ 75% of O2 have dissociated from the Hb
explain what 6.5kPa (pO2) is on the oxygen dissociation curve
-75% saturation of haemoglobin with oxygen
-at resting tissue
-unloads ~ 25% O2
explain what 13kPa (pO2) is on the oxygen dissociation curve
-98% saturation haemoglobin with oxygen
-gas exchange site (alveoli)
-high pO2 low pCO2
- Hb had high affinity for O2
what happens to haemoglobin as partial pressure of oxygen increases
as pO2 increases diffusing gradient into Hb increases = first O2 molecule binds = changes shape (conformational change) =easier for O2 to bind
explain the 3 stages of the oxygen dissociation curve
1) haem groups are in the centre of the molecule = difficult to bind O2
2) the shape change after first O2 binds = allows O2 to associate more easily with second and third haem group
3)Difficult for O2 to combine with final haem group = difficult to achieve 100% saturation
why is oxygen dissociation curve of a fétus to the left of the adult haemoglobin curve?
-feral haemoglobin has a higher affinity for oxygen than adult haemoglobin
-placenta has low pO2
-fétus haemoglobin is still able to take up oxygen in placenta at lower pO2
