Gas transport - carbon dioxide Flashcards
Which 3 ways is CO2 transported in the blood? Provide percentages.
As dissolved CO2 – 10%
As bicarbonate (HCO3-) – 69%
As carbamino compounds – 21%
Carbon dioxide reacts with water to form what?
Carbonic acid – H2CO3
Carbonic acid dissociates to form what?
H+ and HCO3-
What is the definition of an acid?
Any chemical that can donate H+ (proton)
What is the definition of a base?
Any chemical that can accept H+
Describe the nature of dissociation of weak acids in solution
Weak acids, such as carbonic acid, only partially dissociate in solution
A weak acid with its conjugate base forms what?
A buffer pair
What is the normal pH range of blood?
7.35 – 7.45
What are the 2 categories of acids in regards to H+ production?
Volatile and non-volatile acids
What are volatile acids?
Acids that can easily be converted to gases
What are volatile acids excreted by?
Lungs
What are non-volatile acids excreted by?
Kidneys
The Henderson-Hasselbalch equation allows us to calculate what?
The pH based on measurements of HCO3- and CO2
Describe how pH would be restored if too much H+ was produced.
H+ reacts with bicarbonate ions to form CO2. CO2 is breathed out, restoring pH
Describe how pH would be restored if concentration of CO2 was too high.
Kidneys excrete less HCO3-, raising HCO3- plasma and restoring pH
The reaction between CO2 and H2O is catalysed by which enzyme?
Carbonic anhydrase
Where is the carbonic anhydrase enzyme found and not found?
Found in erythrocytes but not in plasma
When CO2 reacts with H2O in red blood cells, the reaction is promoted by the removal of the products (H+ and HCO3-). How are they ‘removed’?
H+ is buffered by haemoglobin and HCO3- is transferred to plasma
The buffering ability of haemoglobin with H+ ions is enhanced by what?
Deoxygenation
What is the Haldane effect?
The ability of deoxygenated haemoglobin to carry more carbon dioxide than in the oxygenated state
Describe how the Haldane effect works.
H+ is buffered by haemoglobin. This ability is enhanced when the haemoglobin is deoxygenated, and reduced when haemoglobin is oxygenated. So, deoxygenated haemoglobin can more effectively buffer H+ ions.
