Buffers in Biological systems

Buffers in Biological systems

Buffers

Buffers in the cosmetic industry

• Buffer solutions maintain their pH when small amounts of acid or base are added.
• A Biological Buffer solution maintains the optimum pH ranges in living systems; changes in blood pH could disrupt biochemical reactions and even cause death.
• Buffers contain a mixture of a weak acid with its conjugate base.

Buffers in the body

Buffers in the ocean

• Human skin is naturally a little acidic

• Ideal pH around 5.5

• Products have to soften and protect in one package

• Some of the ingredients are stable for a certain time at different pH values

• Develop products containing 2 separate emulsions.

• Which are only mixed together to the point when it is being rubbed onto the skin.

• To do this 2 buffers selected for the 2 different layers. Each buffer is chosen so its pKa is close to the desired pH value.

• Also the product when mixed together cannot be damaging for the skin.

Buffers in the body

• Two important biological buffer systems are the dihydrogen phosphate system and the carbonic acid system.
• The phosphate buffer system operates in the internal fluid of all cells. This buffer system consists of dihydrogen phosphate ions (H2PO4-) as hydrogen-ion donor (acid) and hydrogen phosphate ions (HPO42-) as hydrogen-ion acceptor (base).
• Equilibrium: H2PO4-(aq) H+(aq) + HPO42-(aq)
• If additional hydrogen ions; equilibrium shifts to the left.
• If additional hydroxide ions; equilibrium to the right.
• Another biological fluid that needs buffers is the blood plasma.
• In blood plasma, the carbonic acid and hydrogen carbonate ion equilibrium buffers the pH.
• In this buffer, carbonic acid (H2CO3) is the hydrogen-ion donor (acid) and hydrogen carbonate ion (HCO3-) is the hydrogen-ion acceptor (base): H2CO3(aq) H+(aq) + HCO3-(aq)
• This buffer functions in exactly the same way as the phosphate buffer.
• Additional H+ is consumed by HCO3- and additional OH- is consumed by H2CO3.

Buffers in food

• Ocean Water (pH 7.9-8.4)

• To increase the pH of an acid solution, add salt or other minerals.

• Since ocean water naturally contains a lot of dissolved salts and other minerals it could be considered to be buffered naturally.

• You wouldn't need to add more minerals or buffering agents to ocean water since it has a natural pH above 8, and 7 is considered neutral.

• Coral reefs are built from limestone by the reaction Ca2+ + CO32- == CaCO3, Acidifying the ocean decreases the concentration of CO32- ions, which by le Chatlier’s principal shifts the equilibrium toward the left, tending to dissolve CaCO3.

• CaCO3 tends to dissolve in the deep ocean, both because of the high pressure and because the waters have been acidified by CO2 from rotting dead plankton.

• Elevated CO2 levels also affect fish and other aquatic organisms, in part because of the decrease in pH, but also because CO2 is what heterotrophic organisms try to exhale.

• The natural pH of the ocean is determined by a need to balance the deposition and burial of CaCO3 on the sea floor against the influx of Ca2+ and CO32- into the ocean from dissolving rocks on land, called weathering. These processes stabilize the pH of the ocean, by a mechanism called CaCO3 compensation.

• In blood plasma, the concentration of hydrogen carbonate ion is about twenty times the concentration of carbonic acid.
• If the pH falls below this normal value, acidosis is produced.
• If the pH rises above the normal value, alkalosis occurs.
• The concentrations of hydrogen carbonate ions and of carbonic acid are controlled by two independent physiological systems.
• Carbonic acid concentration is controlled by respiration that is through the lungs.
• The concentration of hydrogen carbonate ions is controlled through the kidneys. Excess hydrogen carbonate ions are excreted in the urine.
• The carbonic acid-hydrogen carbonate ion buffer works throughout the body to maintain the pH of blood plasma close to 7.40 by eliminating either the acid (carbonic acid) or the base (hydrogen carbonate ions).

• Food spoilage can be caused by a combination of various factors – such as light, oxygen, heat, humidity and/or many kinds of organisms (Bacteria, Yeasts and fungi).
• We try to reduce spoilage by keeping certain foods in the dark, in airtight containers and/or in refrigerators
• Most microorganisms thrive in neutral surroundings which increases their metabolism and hence they multiply fast.
• Important factor in food spoilage is the buffer capacity which describes the amount of acid or base required to change the pH of the food.
• Processed foods (e.g. jams) contain buffer systems (such as citric acid) which help to maintain the pH within a range where growth of microorganisms is very slow or non existent.
• This allows flavour and appearance to be maintained and is also critical to the preservation of a number of processed foods.
• In the buffer solution, the weak acid and its salt exist in equilibrium, and this allows them to resist changes in acidity by reacting with any extra hydrogen ions to remove them, or by generating new hydrogen ions when needed. This maintains a constant acidity within the food product.