E&T: Haemoglobin Flashcards
Haemoglobin
Large protein with quaternary structure, with 4 chains each containing a haem group with an iron ion.
Describe haemoglobins affinity for O2
High affinity - each molecule can carry 4 x oxygen
Describe the reaction between oxygen and haemoglobin in the lungs:
Haemoglobin + oxygen oxyhaemoglobin
Partial pressure of oxygen (pO2)
Measure of oxygen concentration
Greater concentration of dissolved oxygen = higher partial pressure
When does oxygen load onto haemoglobin?
Where there’s a high pO2
What happens when there is a high pO2?
Oxygen loads onto haemoglobin
What happens when there is a low pO2?
Oxyhaemoglobin unloads oxygen
What is the pO2 at the alveoli?
High - oxygen loads onto haemoglobin
What happens when cells respire?
Use up oxygen - lowers pO2
Allows red blood cells to deliver oxyhaemoglobin to respiring tissues
Where pO2 is high…
… haemoglobin has a high afinity for oxygen.
Where pO2 is low…
… haemoglobin has a low affinity for oxygen.
Why is the dissociation curve ‘S-shaped’?
- When first O2 molecule combines, shape of Hb changes.
- Makes it easier for more O2 molecules to join = steep curve in middle.
Affinity
Tendency to bind with oxygen
How does a higher partial pressure of CO2 affect haemoglobin?
Makes it give up oxygen more readily.
Explain the Bohr effect:
- High concentration of CO2 causes oxyhaemoglobin curve to shift to the right
- Affinity for oxygen decreases because acidic CO2 changes shape of haemoglobin