3. Oxygen In Blood And Tissues Flashcards
What is cardiac output at rest?
4.5L/min
What are the 2 states of haemoglobin?
T state - low affinity for oxygen, difficult for oxygen to bind
R state - high affinity for oxygen, easier for oxygen to bind
At what pressure is haemoglobin half saturated?
3.5-4kPa
What pressure is haemoglobin saturated above?
9-10kPa
What is the normal Hb concentration?
2.2mmol/L
What is tissue pO2?
5kPa
What happens with a lower tissue pO2?
The more O2 will dissociate from Hb, this will lower saturation of venous blood
How low can tissue pO2 get?
Cannot fall below 3kPa in capillaries supplying most tissues
However the higher the capillary density, then lower the pO2 can fall
What is the Bohr effect?
Acid condition shift dissociation curve to right, low pH promotes T state of Hb - Hb has lower affinity for O2
Where does maximum unloading of oxygen occur?
In tissues where pO2 can fall to low level
Also in conditions where increased metabolic activity results in more acidic environment and higher temperature
In tissues with high capillary density where partial pressure gradient of oxygen can be very small
What is the significance of 2,3-DPG in oxygen dissociation?
Normally consumed rapidly but in hypoxia RBC production of 2,3-DPG increases and facilitates O2 unloading in tissues
Increased with anaemia and high altitude
What happens to carbon monoxide in haemoglobin?
200 times more affinity for Hb as oxygen
Increases affinity for unaffected subunits for oxygen
Leftward shift in ox-haemoglobin dissociation curve, reduced oxygen release in peripheral tissue
What are the symptoms of carbon monoxide poisoning?
Headache Nausea Vomiting Slurred speech Confusion
What is hypoxaemia?
Low partial pressure of O2 in arterial blood
What is hypoxia?
Low O2 levels in body or tissues
