Systems bicarbonate

X 10 M), and an equivalent amount of OH (its usual concentration in plasma) would swamp the buffer system, causing a dangerous rise in the plasma pH. How, then, can this bicarbonate system function effectively The bicarbonate buffer system works well because the critical concentration of H2CO3 is maintained relatively constant through equilibrium with dissolved CO2 produced in the tissues and available as a gaseous CO2 reservoir in the lungs. ... 

Sodium bicarbonate—systemic alkalosis and rebound hypersecretion... 

C. The carbonic acid-bicarbonate system is the most important buffer of the... 

The composite pA of the bicarbonate system, 6.1, may appear to make it ill-suited for buffering blood at physiologic pH of 7.4. Nevertheless, the system is very effective at buffering against additions of noncarbonic acids. Changes in the bicarbonate/carbonic acid ratio in such cases can be regulated by ... 

The answer is C. Ingestion of an acid or excess production by the body, such as in diabetic ketoacidosis, may induce metabolic acidosis, a condition in which both pH and HCOj become depressed. In response to this condition, the carbonic acid-bicarbonate system is capable of disposing of the excess acid in the form of CO2. The equilibrium between bicarbonate and carbonic acid shifts toward formation of carbonic acid, which is converted to COj and HjO in the RBC catalyzed by carbonic anhydrase, an enzyme found mainly in the RBC. The excess CO2 is then expired by the lungs as a result of respiratory compensation for the acidosis (Figure 1-2). The main role of the kidneys in managing acidosis is through excretion of H" rather than CO2. 

The membranes of the tubules contain enzyme and active transport systems. One such important enzyme system is carbonic anhydrase, which you might remember as being necessary for establishing the blood-buffer (bicarbonate) system. It performs the same buffering function here allowing... 

Two especially important biological buffers are the phosphate and bicarbonate systems. The phosphate buffer system, which acts in the cytoplasm of all cells, consists of H2POT as proton donor and HPOf as proton acceptor ... 

Blood plasma is buffered in part by the bicarbonate system, consisting of carbonic acid (H2C03) as proton donor and bicarbonate (HCO ) as proton acceptor ... 

As described in Chapter 2, the usual normal buffer system in culture media is the carbon dioxide-bicarbonate system, analogous to that in the blood. Modifications in the medium pH produce changes to the intracellular pH value, with modifications to enzyme activities. 

Buffers stabilize a solution at a certain pH. This depends on the nature of the buffer and its concentration. For example, the carbonic acid-bicarbonate system has a pH of 6.37 when the two ingredients are at equimolar concentration. A change in the concentration of the carbonic acid relative to its conjugate base can shift the pH of the buffer. The Henderson-Hasselbalch equation below gives the relationship between pH and concentration. 

HA] is the concentration of the acid and [A-] is the concentration of the conjugate base. The pKa of the carbonic acid-bicarbonate system is 6.37. When equimolar conditions exist, then [HA] = [A ]. In this case, the second term in the Henderson-Hasselbalch equation is zero. This is so because [A ]/[HA] = 1, and the log 1 = 0. Thus at equimolar concentration of the acid-conjugate base, the pH of the buffer equals the pKa in the carbonic acid-bicarbonate system this is 6.37. If, however, we have ten times more bicarbonate than carbonic acid, [A ]/[HA] = 10, then log 10 = 1 and the pH of the buffer will be... 

The dibromo derivatives 125a and 126a have been prepared by reaction of the unsubstituted amine 125c and the methanesulphonate salt of 126c with excess bromine in acetic acid. Amines 125b and 126b have been converted to the isothiocyanates 125 and 126 by reaction with thiophosgene in a biphasic chloroform-bicarbonate system. The radiochemical purity and the specific radioactivity of the isothiocyanate 125 were 99.9% and 27.4 Ci mmol -1, respectively. The benzimidazole isothiocyanate 126 has been prepared with >95% radiochemical purity and with specific activity of 16.3 Ci mmol -1. 

An important physiological buffering system active in the blood is the bicarbonate system. Bicarbonate (H2CO3) is a weak acid that is involved in maintaining the pH of human blood in the neighborhood of 7.4. The acid-base equilibration for bicarbonate is expressed... 

Cr(III)EDTA] is known to be catalyzed by the car-bonate/bicarbonate system. 

Bicarbonate system is still the major blood buffer, however... 

As an alternative to carbonate/bicarbonate systems, amino adds (a-aminocarb-oxylic acids) may be used as an eluent [47,48]. Their dissociation behavior is depicted in Fig. 3-36. At alkaline pH, amino acids exist in the anionic form due to the dissociation of the carboxyl group and, thus, may act as an eluent ion. The product of the suppressor reaction is the zwitterionic form with a correspondingly low background conductance. This depends on the isoelectric point, pi, of the amino acid. 

The residual dissodation of the zwitter ion and the background conductance of the eluent is even lower than for the carbonate/bicarbonate system, if amino acids are selec-... 

The blood, for example, is protected by two important buffer systems the hemoglobin system and the bicarbonate system, which stabilize its pH between 7.37 and 7.43. The bicarbonate system is the most important buffer for plasma and interstitial fluids. Neutralizing the skin with sodium bicarbonate is the most natural method. 

The other bicarbonate system of some importance is ammonium bicarbonate, which decomposes in the range of 40-60° C. This material is difficult to process owing to the low decomposition temperature and high rate of decomposition with liberation of strong ammonia odor in the extrusion or injection molding processes. However, ammonium bicarbonate can be... 

The most important extracellular buffer is the carbonic acid-bicarbonate system ... 

There are two explanations for the response of the hgh-antibody system to extremely low current densities. First, it must be recalled that the hormone, antibody, and complex are multivalent. The extreme cases are the charge of -5 on the antibody near the upstream boundary and +17 on the protonated, two-hormone complex near the downstream boundary. In the C02/bicarbonate system, all species except are monovalent. 

Thus, the physiologic regulation of both PCO2 and [HCO/] permit the carbonic acid/bicarbonate system to provide more effective buffering of the extracellular fluids than could be achieved on the basis of chemical buffering alone. 

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