Biological systems blood buffering system

Buffers are extremely important in biological systems. The pH of arterial blood is about 7.4. The pH of the blood in your veins is just slightly less. If the pH of hlood drops to 7.0, or rises above 7.5, life-threatening problems develop. To maintain its pH within a narrow range, blood contains a number of buffer systems. The most important buffer system in the blood depends on an equilibrium between hydrogen carbonate ions and carbonate ions. Dissolved carbon dioxide reacts with water to form hydrogen carbonate ions. 

Polyfunctional acids and bases play important roles in many chemical and biological systems. The human body contains a complicated system of buffers within cells and within bodily fluids, such as human blood. The photo is a scanning electronmicro-... 

The Henderson-Hasselbalch equation was developed independently by the Ameriean biological chemist L. J. Henderson and the Swedish physiologist K. A. Hasselbaleh, for relating the pH to the bicarbonate buffer system of the blood (see below). In its general form, the Henderson-Hasselbalch equation is a useful expression for buffer caleulations. It can be derived from the equilibrium constant expression for a dissociation reaction of the general weak acid (HA) in Equation (1.3) ... 

Since biological systems are dynamic, with many different processes taking place and many different substances present, buffers are necessary to prevent the kind of wide variation of pH that can inhibit proper enzyme catalysis. Thus, a proper pH aids in regulating the reaction rates associated with certain enzymes and maintaining them at levels appropriate for their particular functions. Two important biological buffers are the phosphate buffer system that regulates pH for the fluid inside cells and the carbonic acid buffer system that regulates pH for blood plasma. The chemical equations for these buffers are shown below for an aqueous solution. 

A buffer solution is a solution of(l)a weak acid or a weak base and (2) its salt both components must be present. The solution has the ability to resist changes in pH upon the addition of small amounts of either acid or base. Buffers are very important to chemical and biological systems. The pH in the human body varies greatly from one fluid to another for example, the pH of blood is about 7.4, whereas the gastric juice in our stomachs has a pH of about 1.5. These pH values, which are crucial for proper enzyme function and the balance of osmotic pressure, are maintained by buffers in most cases. 

Buffer systems are particularly important in biological systems. Blood and other body fluids are buffer solutions which prevent small additions of acids and bases from causing drastic changes in the pH. The functioning of the enzymes—the biological catalysts—is very sensitive to pH changes, and if biological systems were not buffered there would be serious variations in the rates of metabolic processes. 

In biological systems, the proton potential fip is often adjusted to certain values in human blood it is fairly close to ( 42.2 0.3) kG, in stomach acid at around — 10 kG, in urine at about —30 kG, and in the small intestine at about 50 kG. There must be buffer systems present that compensate for the water s lack of buffer capacity. Graphically speaking, the two containers in Figs. 7.8b and 7.9 are... 

The control of pH within narrow limits is critically important in many chemical applications and vitally important in many biological systems. For example, human blood must be maintained between pH 7.35 and 7.45 for the efficient transport of oxygen from the lungs to the cells. This narrow pH range is maintained by buffer systems in the blood. 

The carbonate/bicarbonate buffer system is an important biological buffer that is critical in maintaining blood pH. 

Electrodes modified with MN4 complexes were also used recendy to develop detection systems for thiols in analytical microsystems, allowing minimum volume of sample to be analyzed. These miniaturized setups are of particular interest for biological samples, to minimize the required volume and be able to analyze a drop of blood for example, with minimal cost and lower solvent and consumables use. Martin et al. [182] have developed carbon ink microelectrodes containing CoPc for the detection of thiols in simple monochannel microchip. The microsystem was applied to the detection of cysteine, homocysteine and glutathione of artificial sample and in buffer at pH 5.5. The electro-oxidation of cysteine and glutathione occurs at +0.5 V while that of homocysteine occurs at +0.35 V at such modified microelectrode. The microelectrode was then used as amperometric sensor in... 

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