2. Haemoglobin Flashcards
What is haemoglobin role?
Transport o2 around body.
Structure
Large protein - quaternary
4 polypeptide chains
Each chain has haem group which contains iron ion - gives red colour.
Each haemoglobin molecule can carry 4 o2 molecules
Where is oxyhaemoglibin formed ?
Oxygen.
Oxygen loads onto haemoglobin.
Where there is a high partial pressure of oxygen
Eg at alveoli
When does oxyhaoglobin turned back to haemoglobin ?
Near body cells, oxygen unloads from haemoglobin
Where there is a low partial pressure of o2
When cells respire as they use up o2 lowering partial pressure
What does affinity for oxygen mean ?
The tendency a molecule of haemoglobin has to bind with oxygen
This depends upon partial pressure of oxygen and partial pressure of carbon dioxide
What is the partial pressure of oxygen ?
Measure of oxygen concentration
So if there’s more dissolved o2 in cells there’s a high partial pressure
What happens as partial pressure of oxygen increases
Haemoglobin affinity for oxygen also increases
Summary of what is occurring in the alveoli in lungs ?
High o2 conc
High partial pressure of o2
High affinity for o2
Oxygen loads
High saturation of o2
What is occurring at respiring tissue ?
Low o2 conc
Low partial pressure of o2
Low affinity for o2
Oxygen unloads
Low saturation of o2
What do dissociation curves show ?
How saturated haemoglobin is with oxygen at any given partial pressure .
The affinity of haemoglobin for o2 affects how saturated haemoglobin is
What does 100% saturated of oxygen mean ?
Each haemoglobin molecule is carrying 4 molecules of o2
What does 0% saturated of oxygen mean ?
No haemoglobin carrying any o2
What does S shaped graph me ?
When haemoglobin combines with first o2 molecule it’s shape alters in a way that makes it easier for other o2 molecules to join too.
But as haemoglobin starts to become even more saturated it gets harder for more o2 molecules to join.
Causes steep bit in middle where it’s really easy for o2 to joint and shallow bits at the end where it’s harder.
When it’s steep a small change in partial pressure of oxygen causes big change in oxygen carried by haemoglobin
kPa
Kilo pascal
Unit used to measure pressure
How does partial pressure of co2 impact oxygen unloading ?
Haemoglobin will give up o2 at higher partial pressure of carbon more readily
During activity you’ll get more o2 to cells
