transporting carbon dioxide

Question 1

how is carbon dioxide transported in blood

Answer 1

5% dissolved in plasma
10-20% form carbaminohaemoglobin
75-80% converted to hydrogen carbonate ions, diffuses into plasma

Question 2

how are hydrogen carbonate ions converted

Answer 2

dissolved carbon dioxide reacts slowly with water to form carbonic acid, sped up by high levels of carbon anhydrase in cytoplasm
carbonic acid partially dissociates to form hydrogen carbonate ions and hydrogen ions

Question 3

how is haemoglobinic acid formed

Answer 3

H ions reduce pH, could be harmful to the cell if left free in cytoplasm
haemoglobin resolve by buffering up H ion
H ion bind to haemoglobin, changes structure
reduces Hb’s oxygen affinity
oxygen unloaded from Hb, Hb only bound with H ion, forming haemoglobinic acid

Question 4

what is the chloride shift

Answer 4

negatively charged hydrogen carbonate diffuse out of cell, cause rbc to become more +
chloride ions move into rbc, maintain electrical balance

Question 5

how can carbon dioxide be released

Answer 5

hydrogen carbonate ions transported back into rbc, chloride ions diffuse down electrochemical gradient back out of rbc into plasma

H ion dissociate from Hb, bind to hydrogen carbonate, form carbonic acid

carbon dioxide dissociate from carbaminohaemoglobin
concentration of co2 within alveoli is low, carbon dioxide diffuse from blood to alveoli, exhaled