Hi everybody, Dr. Mike here. In this video, I want to talk about buffers within the body. [Music] Now, buffers resist drastic changes in pH. We know that our blood has a pH of between 7.35 and 7.45. That's worth putting up. pH of 7.35 to 7.45. And if the blood pH goes below 7.35, it's becoming too acidic. If it goes above, it's becoming too alkalinic. That means that the concentration of hydrogen ions, which dictates the pH is either going to be too much if it goes in this direction, too many hydrogen ions, or not enough hydrogen ions if it goes in this direction. So what happens in the body is if we don't have enough hydrogen ions, we need to make more. If we do have too many hydrogen ions, we need to reduce it. And this is what buffers do. They resist these drastic changes in pH. All right? So for example, I want to talk about a quick buffer. And a buffer that looks like this H2 CO3. What this is called is carbonic acid. And you should know that the definition of an acid is anything that can donate a hydrogen ion. So that means that this carbonic acid can give us a hydrogen ion. Now if it does give us a hydrogen ion, what are we left with if we take one hydrogen out of this? We're left with one hydrogen, one carbon, and three oxygen, which is H3. And because we stole a positive from this, it's left with a negative. And this is called bicarbonate ion. Bicarbonate ion. And this is our hydrogen ion. Again, it's the concentration of the hydrogen ion that dictates the pH. So what we've got here is this a weak acid which donates a small number of hydrogen ions and leaves us with a weak base. Now the definition of a base is something that can mop up hydrogen ions. It can bind to hydrogen ions which means if that can bind to that this is a reversible equation and so this can also go in this direction. Now what we have here is a very simplistic buffer system where if we don't have enough hydrogen ions the weak acid will split apart and release hydrogen ions. If we've got too many it will bind to bicarbonate and go in that direction. Now our body utilizes this reaction but with the addition of some other parts. For example, carbon dioxide and water. If you bind carbon dioxide and water, have a look, there's one carbon, there's the one carbon. Two + one oxygen is three oxygen. Two hydrogen, two hydrogen. If you bind carbon dioxide with water, you get carbonic acid. So, let's write these down just for completion sake. Carbon dioxide and water. All right? And that can split itself apart to produce these two. So, that's reversible as well. What we've now drawn up here is something called the bicarbonate buffering system. And this is one of the most important biological buffers that we have. Now, let me talk about it in regards to how it actually works. All right, this end of the equation deals with the lungs. This end of the equation deals with predominantly the kidneys. Now, this is important because when we look at imbalances in regards to pH, we can say if something's wrong here, it could be metabolic or kidney caused. If something's wrong here, then it could be respiratory cause. And this is going to be the basis of respiratory versus metabolic acidosis or alkyossis. Right? That's for another lecture. But let's think about like this. Let's just say we do not have enough hydrogen ions in the body. If we don't have enough hydrogen ions, the pH is going up. Right? So remember, it's a reverse logarithmic equation. Have a look at my previous video about calculating pH. Right? We don't have enough hydrogen ions. How do we create more? Let's have a look. Carbon dioxide. This is a byproduct of respiration. Breathe in oxygen. Our mitochondria utilize that oxygen and it produces ATP, water, and carbon dioxide. And we don't like carbon dioxide. We want to breathe it out. But in order to go from the cells to our lungs to breathe out, it has to go in our bloodstream. So when carbon dioxide hops in our bloodstream, most of our bloodstream's water. Inevitably, all our carbon dioxide is going to be binding to that water. and it will be producing carbonic acid. But because carbonic acid is a weak acid, hates itself, splits itself apart and produces hydrogen ions. Which means one way we can increase the concentration of hydrogen in our body is through the accumulation of CO2. How can we accumulate CO2? I'll show you. Hold your breath. If you're holding your breath, you're not breathing out. And this is what happens. Some individuals who do not have a high enough concentration of hydrogen ions in their blood, they may be holding their breath a little bit. Their breathing will be different. Let's think of it flipped. What if we have too many hydrogen ions? Well, if we have too many, the bicarbonate will mop it up and produce carbonic acid, which will then split up and produce water and carbon dioxide. So if we are acidic and our pH is too low because we have too many hydrogen ions, we end up producing more carbon dioxide which means the patient may breathe more. So the respiration can be an indication of the blood pH. And you can also see if we don't have enough hydrogen ions, it goes in this direction. If we have too many, it goes in this. And this is the bicarbonate buffering system.