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BUFFERS.

BUFFERS. A BUFFER CONSISTS OF A WEAK ACID AND ITS CONYUGATE BASE THAT CAUSE A SOLUTION TO RESIST CHANGES IN pH WHEN AN ACID OR A BASE IS ADDED. IF H IONS ARE ADDED, THEY COMBINE WITH A WEAK BASE. IF H IONS ARE REMOVED (BY ADDING A BASE), THE WEAK ACID DISSOCIATES, REPLACING THEM. .

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BUFFERS.

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  1. BUFFERS. A BUFFER CONSISTS OF A WEAK ACID AND ITS CONYUGATE BASETHAT CAUSE A SOLUTION TO RESIST CHANGES IN pH WHEN ANACID OR A BASE IS ADDED.IF H IONS ARE ADDED, THEY COMBINE WITH A WEAK BASE.IF H IONS ARE REMOVED (BY ADDING A BASE), THE WEAK ACIDDISSOCIATES, REPLACING THEM.

  2. 2. FACTORS DETERMINE THE EFFECTIVENESS OF A BUFFER • pKa OF THE ACID RELATIVE TO THE pH. A BUFFER WORKS BEST WITHIN 1 pH UNIT OF ITS pKa (THE CONCENTRATION RATIO OF THE UNDISSOCIATED ACID TO ITS CONYUGATE BASE IS BETWEEN 1/10 AND 10/!, i.e., BETWEEN 1 pH UNIT BELOW AND 1 UNIT ABOVE THE pKa). • A BUFFER IS MORE EFFECTIVE THE MORE CONCENTRATED IT IS. (A MORE CONCENTRATED SOLUTION CONTAINS MOR BUFFER MOLECULES).

  3. BODY FLUIDS MUST BE PROTECTED AGAINST CHANGES IN BECAUSE MOST ENZYMES ARE VERY pH SENSITIVE AND THIS MECHANISMS MUST BE CONSTANTLY ACTIVE, BECAUSE META- BOLISM INVOLVES THE PRODUCTION OF ACIDS AND BASES (ESPECIALLY ACIDS).. IN THE LONG RUN, EXCESS ACID OR BASE IS ELIMINATED VIA THE KIDNEYS AND THE LUNGS. IN THE SHORT RUN, THE BODY IS PROTECTED AGAINST pH CHANGES BY BUFFERING SYSTEMS.

  4. 2 MAIN BUFFERS OCCUR IN THE BLOOD : - THE BICARBONATE BUFFER - A BUFFER INVOLVING THE OXYGEN-CARRYING PROTEIN HEMOGLOBIN.THESE MECHANISM NORMALLY ACT TO MAINTAIN BLOOD pHBETWEEN 7.37 AND 7.43.

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