Chemical Buffer Systems – Acid-base Balance (Nursing)

by Jasmine Clark

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    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.

    About the Lecture

    The lecture Chemical Buffer Systems – Acid-base Balance (Nursing) by Jasmine Clark is from the course Fluid, Electrolyte, and Acid-base Balance – Physiology (Nursing).

    Included Quiz Questions

    1. Hydrogen ions specifically
    2. Potassium levels specifically
    3. CO2 in circulation
    4. Bicarbonate only
    1. Hydrochloric acid
    2. Carbonic acid
    3. Dihydrogen phosphate
    4. Phosphoric acid
    1. Carbonic acid
    2. Hydrochloric acid
    3. Nitric acid
    4. Chloric acid
    1. Urine and intracellular fluid (ICF)
    2. Urine and plasma
    3. Plasma and intracellular fluid (ICF)
    4. Urine and extracellular fluid (ECF)

    Author of lecture Chemical Buffer Systems – Acid-base Balance (Nursing)

     Jasmine Clark

    Jasmine Clark

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