chloride shift?

[yjj8817]

So I have been listening to EK osmosis to learn about chloride shift and it said that because bicarbonate ion comes into the RBCs as CO2 is used up, the chloride ions leave when the RBCs are at the lungs.


It also said that arterial blood has less chloride than veins. Can anyone please explain this part? Why does arterial blood have less chloride?

Thank you!

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[NextStepTutor_2]

This is actually a mistake on their part. There is a list of errors for this series that you should definitely google if you use Audio Osmosis. To explain, when intracellular bicarbonate increases, bicarbonate leaves the cell in exchange for chloride. Therefore, since CO2 levels are higher in venous blood than in arterial blood, the opposite would be true for chloride levels in the blood; arterial blood has a higher chloride concentration than venous blood.

 

[yjj8817]

This is actually a mistake on their part. There is a list of errors for this series that you should definitely google if you use Audio Osmosis. To explain, when intracellular bicarbonate increases, bicarbonate leaves the cell in exchange for chloride. Therefore, since CO2 levels are higher in venous blood than in arterial blood, the opposite would be true for chloride levels in the blood; arterial blood has a higher chloride concentration than venous blood.

your explanation isn't making sense to me....at veins, since the CO2 moves in, intracellular bicarbonate increases. Therefore, the bicarbonate leaves the cell in exchange for chloride. Doesn't this mean than vein should have a high concentration of Cl-?

 

[NextStepTutor_2]

I was unclear earlier... let's clarify by separating the blood into its components and considering each. The arterial blood cells would have a higher chloride concentration than venous blood cells. You could then say that arterial plasma has a lower chloride concentration than venous plasma.

 

[Czarcasm]

This is actually a mistake on their part. There is a list of errors for this series that you should definitely google if you use Audio Osmosis. To explain, when intracellular bicarbonate increases, bicarbonate leaves the cell in exchange for chloride. Therefore, since CO2 levels are higher in venous blood than in arterial blood, the opposite would be true for chloride levels in the blood; arterial blood has a higher chloride concentration than venous blood.

I'm sorry but I don't think this is true. Arteriole blood is O2 rich. In the capillaries, that O2 will diffuse through the interstitium while CO2 from tissues will diffuse into blood plasma and then into RBC's. A lot of this CO2 is converted to bicarbonate and protons via carbonic anhydrase in RBC's (although this can occur to a very small degree in blood plasma also). From there, bicarbonate is transported OUT of the RBC (nto blood plasma) in exchange for chloride ions INTO the RBC (out of plasma). For the veins, this must mean it's poor in chloride ions (most are in RBC). In the lungs, the opposite is true. Bicarbonate readily diffuses back into RBC's to be converted to CO2 so that it could be readily exhaled. At the same time, while bicarbonate enters the RBC, chloride is tranported out. So the plasma in the pulmonary veins is very rich in chloride ions.

 

[Czarcasm]

So I have been listening to EK osmosis to learn about chloride shift and it said that because bicarbonate ion comes into the RBCs as CO2 is used up, the chloride ions leave when the RBCs are at the lungs.


It also said that arterial blood has less chloride than veins. Can anyone please explain this part? Why does arterial blood have less chloride?

Thank you!

Edit: nvm, misread that. The wording was confusing, but you should realize they're referring to blood plasma, not chloride concentration in RBC's. Their reasoning is in line with my explanation above.