Blood buffering system

Probably an example and problems derived from the carbon dioxide-blood buffer system in humans should be in every physical chemistry course. What a rich, complex example this is from Henry s law for the solubility of carbon dioxide in water (blood) to buffer capacity, that is, the rate of change of the law of mass action with proton concentration. The example can be expanded to include nonideal solutions and activities. How many physical chemistry courses use this wonderful and terribly relevant to life example First-year medical students learn this material. 

Later, Doisy improved the methods used for the isolation and identification of insulin and contributed to the knowledge of antibiotics, blood buffer systems, and bile acid metabolism. 

Recall from Chapter 7 that, because the equilibrium constants of the blood buffer systems change with temperature, the pH of blood at the body temperature of 37°C is different than at room temperature. Hence, to obtain meaningful blood pH measurements that can be related to actual physiological conditions, the measurements should be made at 37°C and the samples should not be exposed to the atmosphere. (Also recall that the pH of a neutral aqueous solution at 3TC is 6.80, and so the acidity scale is changed by 0.20 pH unit.)... 

When a person exercises, muscle contractions produce lactic acid. Moderate Increases In lactic acid can be handled by the blood buffers without decreasing the pH of blood. However, excessive amounts of lactic acid can overload the blood buffer system, resulting In a lowering of the blood pH. A condition called... 

Blood buffers, urinary system, and respiratory system. The blood buffer system is the fastest to react. 

The blood buffering system depends on two critical equilibria. Garbon dioxide reacts with water to form carbonic acid and carbonic acid reacts with water to form hydronium ion and bicarbonate ion, as shown here. 

Antacids are bases used to neutralize the acid that causes heartburn. The most common antacid ingredients are magnesium and aluminum hydroxides, and bicarbonate or carbonate salts (Table 9.4). Baking soda (sodium bicarbonate) was used to relieve indigestion before many of the other commercial products became available. The bicarbonate ion, a basic anion of a weak acid, reacts with the hydronium ion from hydrochloric acid to form carbonic acid, which decomposes to give carbon dioxide and water. Note this is the same mechanism by which the blood buffering system neutralizes acid. 

Chapter 9 focuses on acids and bases and their chemistry. This chapter now explains how to quickly estimate pH from hydronium ion or hydroxide ion concentrations to a reasonable degree of accuracy without the use of calculators. The non-hnearity of the pH scale is emphasized and the blood buffering system is introduced. The practical acid-base properties of many common household chemicals are discussed. 

Bicarbonate acts not only as a blood buffer system, but also represents the main form in which CO2 is transported from respiring tissues to the lungs for expiration, Some CO2 is transported as carbamino groups of proteins Protein-NHj + COj Protein-NH-COOH Protein-NH-COO-+ H and about 80 % of CO2 is transported as bicarbonate. The different forms of blood CO2 are in equilibrium ... 

However, since the respiratory quotient is usually greater than 0-7, other blood buffer systems, notably the Na2HP04/NaH2P04 system, also operate to keep the pH change within narrow limits. 

The blood buffering systems (although this is only a temporary measure). 

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