Haemoglobin and Gas Transport Flashcards
How much oxygen will dissolve in 1l of plasma?
3ml
What does the partial pressure tell us?
- The amount of oxygen in solution- not bound to Haem.
- The force pushing the oxygen out of the alveoli and into the haemoglobin.
What is the partial pressure of oxygen in alveoli?
100mmHg
How much oxygen can we transport with Haemoglobin?
200ml/l
So with each CO = 200 x 5 = 1000ml per minute
How much oxygen do our cells need?
250ml of Oxygen per minute.
Define Co-operative binding
When one molecule of O2 is bound it increases the affinity of the Haemoglobin to other O2 molecules.
Does the Partial pressure change?
No
- the high affinity of Haem pulls O2 out of solution
- this maintains the partial pressure gradient
- meaning o2 keeps entering the blood.
Name the main type of haemoglobin
Adult Haem= HbA
Makes up 92%
What are the other forms of Hb?
HbF = Foetal Haem= higher affinity than HbA
HbA2 (delta instead of beta)
Myoglobin- found in muscle cells.
HbA1 (a/b/c) - show the exposure to glucose
At 40mmHg what is the Haemoglobin saturation?
75%
Below 40mmHg = death zone.
Why is this important?
It means that even in places with a lower partial pressure of O2 the haemoglobin can still supply cells.
What effect does Anaemia have on Partial Pressure?
None- there is lower levels of Haemoglobin
But partial pressure only refers to the plasma.
What is the effect of lowering the affinity of Haemoglobin?
- More O2 is offloaded to tissues
- The curve shifts to the right (need higher PaO2 to achieve same result)
What would lower the affinity of Hb?
- High temperature
- High PaCo2
- Low pH
- Higher 2,3-DPG
Why is Carbon Monoxide a problem?
It has an affinity which is 250x higher than O2
- Symptoms- cherry red skin, hypoxia, anaemia, nausea.
- treat with 100% O2