Saturday, October 13, 2012

Oxygenation and Ventilation Are Not Opposites

Breathing has two parts: bringing oxygen into the body, and expelling carbon dioxide from the body. Both are incredibly important.

Why is oxygen important?
With oxygen cut off for a few minutes, the body can't effectively make energy (ATP) and will start shutting down.

Why is getting rid of CO2 important?
If CO2 builds up in the body high enough and for long enough, it can actually put you into a coma. A good way to think about it is that there are actually 3 waste-disposal organs in the body.
1. Intestines - stool
2. Kidneys - urine
3. Lungs - CO2

CO2 is a waste byproduct of the mitochondria doing their work and is just as important to get rid of as what is in urine and what is in stool.

What is Ventilation?
You will often hear people talk about breathing in terms of oxygenation and ventilation. Oxygenation is the breathing in of oxygen, but ventilation is not technically the equivalent word for blowing out carbon dioxide. We actually don't have a good word to specifically mean that. It's a small point, but a conceptually important point:

Ventilation = Air Movement (not the act of blowing off CO2)

Ventilation simply means moving air in and out of the lungs. If this does not happen then yes, you will not be able to get rid of CO2 because air is not moving out of the lungs. But you will also not be able to bring O2 into the lungs if there is no air movement/ventilation so you will not be oxygenating either. 

So ventilation is air movement which is necessary for both oxygenation and blowing off CO2 (we really need a noun specifically for blowing off CO2 . . . expulsion?). Put in another way:

Oxygenation           CO2 Expulsion

Ventilation is the heading under which both oxygenation and blowing off CO2 fall. Again, it may be a small point, but explicitly defining these terms and how they relate to each other makes understanding mechanical ventilation much more conceptually easy when you first start learning about it.

1 comment:

  1. I like to think of the concept of oxygentaion and ventilation like a central air heating system. If you think of the body like the rooms of a house, the duct system as the lungs, and the heat or AC like the oxygen it's easier to imagine.

    If you have a really great AC system (oxygen), but the fan (ventilation) isn't working or is working at minimum capacity, the fact that you have all that great AC (oxygen), doesn't really matter. If you have a really great fan (ventilation), but not a good AC(oxygen), you are also stuck.

    You can kind of think of blowing off CO2 the same way. CO2 is the bi-product of energy being created in the body, you can think of Co2 like the smoke from a fire, probably the easiest analogy. Imagine you are in a room that is smokey, the easiest way to get rid of the smoke is to use a fan and blow it out. In the case of your body, the best 'blower' is the lungs.