First here is the actuall link to the thread, lol as you can see I started out with a ******ed question.
http://forums.studentdoctor.net/showthread.php?t=368447
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Now, here is the information that was most relevent to this topic of lecture 7 in the EK version 6 book for BIOLOGY!!!
*******************************(QUESTION)
Yes, there is mad learning going on here... and because I want to do something with the heart one day I am loving it as a premed... I know the stuff is blowing my mind right now but hey I am glad these people are on this level... shows me that being a doctor is the most prestigous thing on earth.
Ok, here is my question slash concern...
This is a cardiovascular question...
When you exercise heavy your RBC increase in CO2 and thus a decrease in PH causing it to become acidic... why, why does CO2 specifically cause lower PH? where exactly is this coming from in a mechanistic way? As well, is that the true reason why we breath harder to expel more CO2 and thus balance out the PH. please give the lamen term answer... The reason why I am having a problem of understanding why CO2 causes a higher PH is because in order to make the CO2 and H2O the bicarbonate ion has to come into the RBC and react with an H+ ION... I would think this reaction right here would cause an increase in PH even if the result is an increase in CO2... Meaning CO2 isn't even acidic is it?
Second, heavy breathing rate expells more CO2 and thus increases PH Again, I am just having a wEird understanding of this mechanism... I think part of the problem might come from the fact that when O2 is entering into the RBC what type of PH change might that cause?
****************************(REPSONSE Wizard of Oz)
As you already know, the equation is CO2 + H2O to H2CO3 to H+ + HCO3-
If your breathing slows or CO2 can't leave for some reason, CO2 will get backed up and drive the equation to the right by mass action. That's where the H+ (low pH) comes from. Yes the H+ was needed to make the CO2 + H2O in the first place, but now the equation is being pushed back the other way because the CO2 isn't leaving like it's supposed to.
Exercise will also increase lactic acid production. You can try to fix this by blowing off CO2 as well.
Acid will shift hemoglobin O2 binding to the right decreasing O2 affinity, but I don't think you want to go into that stuff here.
************************(additional RESPONSE)
Heavy breathing (specifically DEEP breathing) blows off CO2. By blowing off CO2, you're getting rid of an acidic product, which will increase the pH.
Yes. Lactic acid from your muscles will increase body pH. Poorly controlled diabetics will also have excessive acid in their bodies. Certain substances (aspirin, methanol, antifreeze) will contribute to the acid load in your body.
Take home point is: Don't drink antifreeze, kids. Even if it does taste pleasantly peppermint-y. (It supposedly tastes like peppermint schnapps. Don't ask - this is just what I've heard.)
[I'm not even going to ask the inevitable follow-up question. I just wouldn't respect myself if I did.]
***************(ADDITIONAL RESPONSE)
Yes, metabolic acidosis can occur too.
There shouldn't be any limiting reagents in an equilibrium reaction. If you run out of any of the above, you're probably dead. It's probably best to ignore the RBC membrane to understand this material. The ions will move to their required places via transport mechanisms to maintain homeostasis.
BTW CO2 can react with the peptide chain of Hb to also decrease oxygen affinity.
I think that you're making this subject too complicated.
*********************(MY FINAL RESPONSE TO THAT QUESTION)
First thank you so much... the only reason why I called it cardiovascular is because in my examkracker book that is the section the material came up in... Again, I am only dealing with the heart lungs and blood for this section so that is why I was focusing on it so much... LOL that is where the first question came from as well...
Now, I am a Chemistry major so sorry I got a little deep into the subject but Believe me you all helped so much in what you where explaining that I totally get the concepts now... I mean the take home message was that increase of CO2 decreases PH because of the IONS and Carbonic Acid forming.
Lastly, the rate limiting reaction could occur, while yes the reaction is in equalibrium that is only via the reaction mechanism... if more of a substance is available then more amounts of it will be produced to it limiting reagents capacity... Obviously the limiting reagent is CO2 but I was just being a nerd and saying that if you had way too much CO2 and very little water... an actual increase of water would be the main culprit for causing acidosis.... I know I know... LOL I hear the birds chirping but I gotta be able to contribute some braniac knowledge...
Especially for my oh so bad initial question...
Again, thanks this thread was actually productive and I am going to put the important parts in my diary over on the MCAT thread...
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Summary of recent websites that were really awsome finding out extra information
http://www.rxlink.com
http://pathmicro.med.sc.edu/book/video.htm
r!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Happy Learning... how this thread was helpful...
Oh and P>S> my next strat when I am done with bio is to do the Physics and Verbal at the same time... One to just get used to reading passages... but as well the book for verbal for some reason has a little math review... as well, the verbal book is extremly small.