Gas transport in the blood 2 Flashcards
Where must oxygen from the lungs be transported?
To the tissues for cellular use
Where must CO2 produced by cellular mechanisms be transported?
To the lungs for removal from the body
What are the 3 means of CO2 transport in blood?
- Solution (10%)
- As bicarbonate (60%)
- As carbamino compounds (30%)
What is the main transport mechanism of CO2 in the blood?
As bicarbonate (60%)
What is Henry’s Law?
The amount of a gas dissolved in a liquid (e.g. blood) at a constant
temperature is:
proportional to the partial pressure of the gas in equilibrium with the liquid
How is sufficient CO2 transported in blood despite having a much lower partial pressure than oxygen?
Carbon dioxide about 20 times more soluble than oxygen
What proportion of CO2 is carried in solution?
10%
How is bicarbonate formed in the blood?
CO2 reacts with H20 in the presence of carbonic anhydrase to form carbonic acid, which then dissociated to form H+ and HCO3-
What can H2CO3 dissociate into?
CO2 and H20
Or
H+ and HCO3-
What is the catalyst in the following reaction:
CO2 + H2O –> H2CO3
Carbonic anhydrase
How does CO2 diffuse from the tissues into blood cells in capillaries?
Via partial pressure gradient
What reaction occurs once CO2 is inside red blood cells?
It will react with water in the presence of carbonic anhydride, leading to formation of bicarbonate
How does bicarbonate enter plasma?
Chloride shift - bicarbonate eneters plasma in exchange for chloride
What reaction occurs once HCO3- is inside the blood plasma?
It will dissociate into H+ and CO2, which will react with haemoglobin
What are carbamino compounds?
Carbamino compounds are formed by combination of CO2 with terminal amine groups in blood proteins
What is the most common terminal amine group CO2 combines with?
Globin of haemoglobin to give carbamino-haemoglobin
Does the reaction of Hb with CO2 require a catalyst?
No, rapid even without enzyme
How is the affinity of Hb for CO2 increased?
If Hb liberates oxygen to become deoxygenated
What is the Haldane Effect?
Removing O2 from Hb increases
the ability of Hb to pick-up CO2 and
CO2 generated H+
What does he Haldane Effect work in synchrony with?
The Bohr Effect
What does the synchrony of the Bohr Effect and Haldane Effect facilitate?
O2 liberation and uptake of CO2 & CO2 generated H+ at tissues
What does the Bohr Effect facilitate?
The Bohr Effect Facilitates the Removal of O2 from haemoglobin at tissue level by shifting the O2-Hb dissociation curve to the right
What shifts the CO2 dissociation curve to the right?
Oxygen
What happens to Hb at the lungs?
It picks up O2
