00:01 So our chemical buffer systems are going to rely on the the properties of acids and bases. 00:09 So strong acids dissociate completely when they're in water. 00:13 So therefore, a strong acid will dramatically affect a pH. 00:20 Weak acids, however, only dissociate partially when placed in water. 00:24 And so they are efficient at preventing dramatic pH changes. 00:30 Strong bases are going to dissociate easily in water and they are going to tie up or hold on to H+ ions. 00:41 Weak bases accept these H+ ions more slowly and again prevent dramatic changes in pH. 00:51 So again, a strong acid like hydrochloric acid is going to dissociate completely into H+ and Cl- thus increasing the H+ concentration, or decreasing the pH. 01:07 However, a weak acid such as carbonic acid does not dissociate completely. 01:14 So if you're going to get some H+ ions as well as some bicarbonate ions, but some of the carbonic acid will remain. 01:24 This is going to cause a less dramatic change in the overall pH of your solution. 01:32 So a chemical buffer system is a system where one or more compounds are going to act to resist these pH changes. 01:41 This resisting of a pH change is referred to as a buffer. 01:45 And this is going to do this when a strong acid or a strong base is added to the buffer system. 01:54 There are three major buffering systems found on our bodies. 01:57 We have the bicarbonate buffer system, the phosphate buffer system, and the protein buffer system. 02:05 A chemical buffer will bind to the H+ if our pH drops and becomes too acidic, or it will release H+ if our pH rises and becomes too alkaline. 02:18 So a mixture of carbonic acid which is a weak acid, and salts of our bicarbonate make up are bicarbonate buffer system. 02:29 This includes things like sodium bicarbonate, which is a weak base. 02:34 This is going to buffer both the intracellular fluid and the extracellular fluid, but it's only important in the buffering of our extracellular fluid compartment. 02:46 So what happens in the bicarbonate system, if a strong acid is added? If it is added, then the bicarbonate will tie up the H+ and form carbonic acid. 03:01 The pH will decrease only slightly unless all of the bicarbonate gets used up. 03:07 so if we use up all of our alkaline reserve. 03:11 Their bicarbonate levels in our body, however, are going to be closely regulated by our kidneys. 03:19 In the bicarbonate buffer system if a strong base is added this is going to cause the carbonic acid to dissociate and donate its H+ ions, so that it can decrease the pH. 03:35 The pH will rise only slightly. 03:39 The H+ ions are going to tie up the base for example, it will tie up hydroxide ions. 03:46 And also in this case, the carbonic acid can supply an almost limitless amount of carbonic acid. 03:55 And this can be subject to respiratory controls. 03:59 Another buffer system in our body is the phosphate buffer system. 04:05 The way the phosphate buffer system works is almost identical to how the bicarbonate buffer system works. 04:12 The components are going to be sodium salts of dihydrogen phosphate, which is a weak acid and monohydrogen phosphate, which is a weak base. 04:22 This is actually going to be an unimportant buffering system in our plasma. 04:27 But it's more effective in buffering the urine as well as our intracellular fluid compartments. 04:33 Where we're going to find our highest phosphate concentrations. 04:39 So in the phosphate buffer system, H+ that is released by our strong acids will be tied up with a weak acid. 04:49 Conversely, strong bases are going to be converted to weak bases in this buffer system. 04:58 Intracellular proteins are the most plentiful and powerful of our buffers. 05:04 So this brings us to our third buffer system which is the protein buffer system. 05:10 Protein molecules are amphoteric, which means they can function as both a weak acid or weak base. 05:17 So when the pH rises or becomes too basic, the organic acid or carboxyl groups can release their H+ ion. 05:27 However, when the pH falls or becomes too acidic, the amino group on the protein can bind to the excess amounts of H+. 05:38 Hemoglobin is an also a protein buffer system and can function as an intracellular buffer inside of our red blood cells.
The lecture Chemical Buffer Systems – Acid-base Balance (Nursing) by Jasmine Clark, PhD is from the course Fluid, Electrolyte, and Acid-base Balance – Physiology (Nursing).
Which is an example of a strong acid?
Which is an example of a weak acid?
The phosphate buffer system works effectively in buffering which body fluids?
5 Stars |
|
5 |
4 Stars |
|
0 |
3 Stars |
|
0 |
2 Stars |
|
0 |
1 Star |
|
0 |