Dr. Andy Galpin

We're going to use carbohydrates or fat as a fuel.

We're going to make ATP.

And then at the end, the final product of all metabolism is going to be water, CO2, and ATP.

So the CO2 concentration increases as metabolic rate increases.

As a result of that, you start then moving CO2 from your tissue into the blood.

Concentrations of CO2 then in blood go up.

You've got chemoreceptors in your brainstem and various other places that are going to be paying extreme attention to the amount of CO2 in your blood.

If CO2 gets really, really high, we call this hypercapnia.

If it gets low, it's called hypocapnia.

Remember those terms.

So hypercapnia, increases in CO2 concentration, actually signal your red blood cells to drop the oxygen on them, making it easier for your muscle to extract and absorb the oxygen.

Effectively, you think about it this way.

If CO2 is high in the blood, your body is under the assumption you're going through a lot of metabolism.

So it's under the assumption that we want to use and need a lot of oxygen.

So it reduces that affinity.

And this is called the Bohr effect.

If you get hypocapnic, again, too low of CO2, it does the opposite.

Now, this is going to be counterintuitive when we talk about things like CO2 tolerance and respiratory rate in future episodes as to why you could potentially have problems with hyperventilation or overbreathing.

So what's happening in this context is those signals are being sent to your brain, and that is interpreting it as saying CO2 is too high.

Let's reduce that.