In this video, we're going to begin our introduction to buffers. First, we need to note that the pH of most living organisms is actually maintained right around a value of 7 or having a neutral pH. Changing the pH even slightly can actually be really harmful to living organisms. It's in the best interest of living organisms to make sure that the pH stays around 7 in its neutral range. In order to ensure that the pH stays around 7, living organisms use what are known as buffers.
Buffers are defined as substances capable of resisting changes in the pH even when acids and bases are added to the solution. Typically, acids and bases would change the pH. However, if buffers are present in the solution, then even when acids and bases are added to the solution, the substance is capable of resisting changes in pH, which means that the pH will not change. This is beneficial for living organisms because if the pH changes too much, then that can be really harmful. Therefore, these buffers are good things that cells use to make sure that the pH is going to resist changes and stay in that neutral range.
Depending on the situation, buffers are capable of either decreasing or increasing the concentration of hydrogen ions in the solution. Living organisms use buffers to help maintain the pH or help maintain homeostasis regarding the pH values. Observe our pH scale, which we know goes from 0 up to 14. We know that values of 0 are acidic and values of 14 are basic. Of course, right in the middle, with the value of 7, that is going to be neutral.
Most living organisms require a pH of about 7 to survive. If the pH were to tip too much to either side, whether too much acid or too much base was added, it could be really harmful. Thus, it's in the cell's best interest to make sure that the pH is maintained and able to resist changes, so that it stays about the same.
Here we're showing you a specific type of buffer called the bicarbonate buffer system, which is found in our blood and helps to maintain the pH of our blood. Notice that on the left-hand side, we're showing you hydrogen ions, and remember that the pH is going to reflect how many hydrogen ions there are. If there are a lot of hydrogen ions, then we would have an acidic solution. Notice that there are not many free hydrogen ions on one side, which means that the pH on that side is going to be higher and it's going to be a basic solution.
Notice here that \( \text{HCO}_3^- \) is part of a buffer system because \( \text{HCO}_3^- \) is capable of accepting hydrogen ions if the hydrogen ion concentration gets too high. In such a scenario when the hydrogen ion concentration gets too high, bicarbonate can act to lower the hydrogen ion concentration by accepting hydrogen ions, and that is going to cause the reaction to go in the direction towards the right, which will increase the pH. So, the pH is increased when \( \text{HCO}_3^- \) accepts hydrogen ions.
However, if the hydrogen ion concentration were to get too low, then this other molecule, which we will refer to from now on as \( \text{HHCO}_3 \) is capable of donating hydrogen ions if it gets too low. You can see that depending on the situation, depending on if the hydrogen ions are too high or too low, buffers, which would include \( \text{HCO}_3^- \) and \( \text{HHCO}_3 \), are capable of either decreasing or increasing the hydrogen ions in the solution. This once again is going to help maintain homeostasis regarding the pH. This year concludes our introduction to buffers and we will be able to get some practice applying these concepts moving forward in our course. So I'll see you all in our next video.