Transport of oxygen in the blood Flashcards
What does oxygen do in the pulmonary capillaries?
Most of it binds to haemaglobin, until haemaglobin is fully saturated
Then it dissolves in the blood, until the pO2 of the blood is equal to the pO2 of the alveoli
What is the equation for the total amount of oxygen in the blood?
Total oxygen = haemaglobin-bound oxygen + dissolved oxygen
Why does most of the oxygen bind to haemaglobin?
Because oxygen has a low solubility coefficient
so it is not very soluble
What does oxygen in the tissue capillaries do?
Oxygen diffuses from the tissue capillaries into the tissue
until the pO2 in the tissue is equal to the pO2 in the tissue capillaries
What is the pO2 in the tissues? Why?
5kPa
Because oxygen diffuses from the tissue into the cells
What is the pO2 in the cells? Why?
3kPa
Because oxygen in the cells is used up in aerobic respiration
What is the minimum pO2 in the tissues? Why?
Higher than 3kPa
Because it needs to be higher than the pO2 in the cells
in order to maintain the partial pressure gradient for diffusion
How many molecules of oxygen can bind to haemaglobin?
Four
one per haem group
What are the different states of haemaglobin?
T state, tense state
R state, relaxed state
What is the tense state of haemaglobin?
Has low affinity for oxygen
What is the relaxed state of haemaglobin?
Has high affinity for oxygen
What promotes the tense state of haemaglobin?
Low pO2
2,3-BPG
CO2, H+
Temperature
How does low pO2 promote the tense state of haemaglobin?
Less oxygen binds to haemaglobin
no conformational change of haemaglobin
remains tense
Where is 2,3-BPG located?
In red blood cells
What promotes the relaxed state of haemaglobin?
High pO2