Test question: Respiring cells release CO2 into the bloodstream

In summary, when cells exhaust their supply of oxygen, carbon dioxide is released and absorbed by red blood cells. This causes the pH level of the blood to drop.
  • #1
Lo.Lee.Ta.
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Test question: "Respiring cells release CO2 into the bloodstream..."

1.
testquestionrespiringcells_zps600ae6a9.jpg




2. For this question, I was thinking about the nature of CO2.
It's not an acid or base, so how could it drop or raise the pH level?!
So I put that the pH level won't change (B), but the real answer is C (it will decrease slightly).


How is this? How can a neutral substance make the blood more acidic?
Or is it really NOT neutral...? Hm.:confused:

Would you please explain why the pH value gets lowered?

Thank you so much! :)
 
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  • #3


Okay, I read the article you posted.

I hope I understood correctly.

So is it that once cells use up oxygen, CO2 is released and then absorbed by red blood cells.
But once the CO2 is absorbed, it combines with H2O to form H2CO3, which dissociates into
H+ and HCO2-.

The H+ plus attached to a hemaglobin, and the HCO2- gets pumped out of the red blood cell. The red blood cell takes in Cl- in its place.

So now the HCO2- is in the blood plasma.

Once the blood gets to the lungs, the HCO2- gets back into the red blood cell and the Cl- gets kicked out. The H+ detaches from the hemaglobin, and so H2CO3 is formed again.

Now the H2CO3 gets broken down again into water and CO2.
The CO2 diffuses into the lungs and is breathed out. ...I guess the water stays.



Okay, makes sense. But weren't they asking about the pH right at the moment when the CO2 leaves the cell (before taken up by the red blood cells)?

And they couldn't be talking about when the HCO2- gets kicked out of the red blood cell and into the plasma because then the blood would be more basic, right?
HCO2- wants a H+, so it is a base, right?
...So I still am not sure as to how the blood gets more acidic when CO2 leaves cells! :/
Hm. =_=
 
  • #4


Adding CO2 to the system is equivalent to adding H2CO3 to the system. Further reactions can lower the effect, but they can't change the direction - adding acid always lowers pH.
 
  • #5


Oh, okay! Since the CO2 combines with water to form H2CO3 (carbonic acid), the blood becomes more acidic.

I guess it was required for us to know the carbonic acid step in order to answer this question!
...(The chapters the test was over did not include information about how CO2 and O2 are expelled and taken up by cells!)

Ugh. =_=# Oh well.

Thank you so much, Borek and jedishrfu! Makes sense now! :D
 

1. What is the process of respiration and how is it related to CO2 release?

Respiration is the process by which cells convert glucose into energy. During this process, carbon dioxide (CO2) is produced as a waste product and is released into the bloodstream.

2. How does CO2 move from cells into the bloodstream?

CO2 is transported from cells to the bloodstream through a process called diffusion. It moves from an area of high concentration (cells) to an area of low concentration (bloodstream).

3. Can respiration occur without the release of CO2?

No, CO2 release is an essential part of the respiration process. Without it, cells would not be able to efficiently convert glucose into energy.

4. What happens to the CO2 in the bloodstream?

Once CO2 is released into the bloodstream, it is transported to the lungs where it is exhaled from the body. The lungs act as the primary organ for eliminating CO2 from the body.

5. How does the release of CO2 affect the body?

The release of CO2 into the bloodstream helps regulate the body's pH levels. Too much or too little CO2 can disrupt the body's acid-base balance and lead to health issues.

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