Haemoglobin Flashcards
Describe the oxygen dissociation curve
- Shape of haemoglobin molecule makes it difficult for first O molecule to bind so at low oxygen conc. little O binds
- first molecule changes quaternary structure of haemg making it easier for the next few molecules to bind to the other subunits
- small increase in partial pressure of O causes a big change in the amount of oxygen that can be carried
- fourth molecule of O is harder to bind because it’s less likely that a single O molecule will find an empty site to bind to because it’s so saturated
- gradient reduces and graph flattens out
Oxygen dissociation curves more to the right means
haemoglobin has a lower affinity for oxygen so more is unloaded easily to respiring tissues
Oxygen dissociation curves more to the left means
Haemoglobin has a greater affinity for oxygen so increases rate of oxygen loading
An active organism will have an oxygen dissociation curve more to the
Right (less saturated at a given p.p which means lower affinity for oxygen = more oxygen supplies to respiring tissues)
When does haemoglobin have a reduced affinity for oxygen?
In the presence of carbon dioxide (where the is a higher partial pressure of CO2)
Describe the behaviour of haemoglobin in the lungs
Partial pressure of CO2 is low
Affinity for O2 is increased
Coupled with high conc of O2 in lungs = increased rate of oxygen loading
(ODC to the left)
Describe the behaviour of haemoglobin in respiring tissues
Partial pressure of CO2 is high
Affinity for O2 is reduced
Coupled with low conc of O2 in muscles = increased rate of oxygen unloading
(ODC to the right)
How does the pH affect oxygen loading at the gas exchange surface
low CO2 higher pH which changes shape of haemoglobin that enables it to load oxygen easily
How does the pH affect oxygen UNloading at respiring tissues
high CO2 lowers pH (more acidic) which changes shape of haemoglobin into one with a lower affinity for O2
