PHYS20008 Lecture Notes - Lecture 22: Carbonic Anhydrase, Extracellular Fluid, Excess Post-Exercise Oxygen Consumption
10 May 2018
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Lecture 22
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- Oxygen dissolved in plasma is very little, oxygen has low solubility in fluid
- Haemoglobin attached to red blood cells have high affinity for oxygen → can bind
100x more oxygen than amount we had solubilised
- Haemoglobin purpose is to transport oxygen to wherever it needs to go
- Despite high affinity of oxygen, need haemoglobin to let go of oxygen to tissues that
need that oxygen
- Haemoglobin depending on partial pressure of oxygen in current environment → will
be willing to let go of oxygen if that partial pressure of oxygen in surrounding
environment drops → the lower that partial pressure is (further left curve gets), the
less affinity haemoglobin has for oxygen → more generous to give that oxygen to the
tissue
- Back in lungs when we have high partial pressure of oxygen (100mmHg),
haemoglobin has very affinity, will bind as much as it can, nearly 100% saturation of
haemoglobin
- Curve shows prediction of how much oxygen haemoglobin will let go of depending on
oxygen content in surrounding environment
- Normally resting cells around 40mmHg → haemoglobin saturated at lungs will end up
dropping off 25% of its oxygen to normal resting tissue → travel around, has buffer
zone, if need more oxygen for particular tissue → has capacity to let go of even more
oxygen
- Setpoint in middle of curve
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- The more acidic something gets → curve shifts to right → haemoglobin is more
generous with giving out oxygen in that particular condition
- As things get hotter → curve shifts to right → haemoglobin gives out more oxygen to
that particular tissue
- The more carbon dioxide in particular environment → the more generous
haemoglobin is in giving out its oxygen
- where/when would curve tend to shift to the right: exercising muscles, increased
metabolism, hot acidic higher partial pressure of carbon dioxide condition
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- Get back to lungs → return to 37 degrees, neutral pH, appropriate level of carbon
dioxide, neutral → curve back to pick up 98% saturation of haemoglobin at lungs
- All effects are local to environment
- Woolly mammoths: specialised form of haemoglobin, much lower body temperature,
low capacity for haemoglobin to give up oxygen to various tissues
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Document Summary
Oxygen dissolved in plasma is very little, oxygen has low solubility in fluid. Haemoglobin attached to red blood cells have high affinity for oxygen can bind. 100x more oxygen than amount we had solubilised. Haemoglobin purpose is to transport oxygen to wherever it needs to go. Despite high affinity of oxygen, need haemoglobin to let go of oxygen to tissues that need that oxygen. Back in lungs when we have high partial pressure of oxygen (100mmhg), haemoglobin has very affinity, will bind as much as it can, nearly 100% saturation of haemoglobin. Curve shows prediction of how much oxygen haemoglobin will let go of depending on oxygen content in surrounding environment. The more acidic something gets curve shifts to right haemoglobin is more generous with giving out oxygen in that particular condition. As things get hotter curve shifts to right haemoglobin gives out more oxygen to that particular tissue.
