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 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 that are 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, 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, it can be really harmful. These buffers are beneficial for cells to ensure that the pH resists changes and stays in the 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. If we look at our image on the left-hand side, we see a pH scale, which we know ranges from 0 up to 14. Values of 0 are acidic, and values of 14 are basic, while a value of 7 is neutral. Most living organisms require a pH of about 7 to survive. If the pH were to tip to either side, too much acid or base could be really harmful. It's in the cell's best interest to ensure that the pH is maintained and able to resist changes, staying about the same.
Here, we're showing an example of the bicarbonate buffer system, which is found in our blood and helps to maintain the pH of our blood. On the right-hand side, we focus on the bicarbonate buffer system, which includes these two molecules that we see here, HCO3− and HHCO3. Notice that on the left-hand side, we are showing hydrogen ions, and remember that the pH reflects the number of hydrogen ions. If there are many hydrogen ions, then we would have an acidic solution. However, if there are not many free hydrogen ions, as shown here where there's no H+ anywhere, that means the pH is high and it's going to be a basic solution.
Here, it is noted that HCO3− is part of a buffer system because it is capable of accepting hydrogen ions if the hydrogen ion concentration gets too high. In such a scenario, bicarbonate can act to lower the hydrogen ion concentration by accepting hydrogen ions. This action causes the reaction to move towards the right, which will increase the pH. The pH is increased when HCO3− accepts hydrogen ions. However, if the hydrogen ion concentration were to get too low, HHCO3 is capable of donating hydrogen ions. Depending on the situation, buffers, which include HCO3− here and HHCO3, are capable of either decreasing or increasing the hydrogen ions in the solution. This helps maintain homeostasis in regards to the pH. This concludes our introduction to buffers and we will be able to get some practice applying these concepts moving forward in our course. I'll see you all in our next video.