MRCP revision battle 40.1: Oxygen dissociation curve
MRCP revision battle 40.2: Carbon monoxide poisoning
MRCP revision battle 40.3: Acetylator status
MRCP revision battle 40.4: Generalised lymphadenopathy
MRCP revision battle 40.5: Acute mountain sickness
MRCP revision battle 40.6: Trisomies - Down's, Edward's and Patau's
MRCP revision battle 40.7: Hereditary angioedema
MRCP revision battle 40.1: Oxygen dissociation curve
The oxygen dissociation curve illustrates now easily haemoglobin gives up oxygen at a certain partial pressure of oxygen.
A shift in the curve to the left means lower oxygen delivery (L for left L for lower delivery). This means the haemoglobin has a higher affinity for the oxygen.
Causes of a shift to the left include:
- less acidity
- lower temperature
- less 2,3 DPG
- HbF
- carboxy/methyl haemoglobin
A shift in the curve to the right means higher oxygen delivery, and hence the haemoglobin has a lower affinity for the oxygen.
Causes of a shift to the right include:
- higher acidity
- higher temperature
- higher levels of 2,3 DPG
The Bohr effect states that the curve will move to the right when there is a higher concentration of CO2 (and hence higher acidity). This explains how the body releases oxygen to the tissues that need it the most.
The Haldane effect states that in the presence of raised oxygen carbon dioxide will bind less well to haemoglobin.
After that chunk of physiology lets go for a bit of poisoning...
