3.2 Transport In Animals - CO2 Flashcards
(12 cards)
How many ways is carbon dioxide transported in?
Three ways
What are the three ways carbon dioxide is transported?
- about 5% is carried dissolved in plasma
-10-20% is combined with the amino groups of haemoglobin in RBCs to form carbaminohaemoglobin
-75-80% is converted to hydrogen carbonate ions in the cytoplasm of RBCs which then diffuse into the plasma
What is carbaminohaemoglobin?
-Some of the carbon dioxide diffuses into the red blood cells and directly binds with the haemoglobin
-This forms carbaminohaemoglobin
-10-20% of carbon dioxide is carried this way
What happens when carbon dioxide slowly reacts with water?
It forms carbonic acid
Why is the formation of carbonic acid sped up in the erythrocytes?
Because of the high levels of carbonic anhydrase in the cytoplasm of red blood cells
What does carbonic anhydrase partially dissociate to form?
Hydrogen carbonate ions
Hydrogen ions
How is haemoglobinic acid formed?
-When carbonic anhydrase partially dissociates into H+ ions.
-Those are harmful if left in the cell
-So Hb buffers the effect by binding to it
-This forms haemoglobinic acid
Whats haemoglobinic acid’s affinity for oxygen like?
The presence of H+ one slightly changes the structure
This REDUCES the affinity for O2
What happens in the chloride shift to the hydrogen carbonate ions?
When carbonic anhydrase partially dissociates, the negatively charged hydrogen carbonate ions diffuse out of the cell
Causing the red blood cell to become more positive
Chloride ions move in to main the electrical balance of the cell
What’s the effect on the cell when
What is the chloride shift?
-When negatively charged hydrogen carbonate ions leave the cell by diffusion
- this makes the red blood cell more positive
-chloride ions will diffuse in to maintain the electrical balance of the cell
At the lungs, what reaction does carbonic Anhydrase catalyse?
Breaks down carbonic acid into carbon dioxide and water
Catalyses the reverse reaction
