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As calculated by the Henderson–Hasselbalch equation, in order to maintain a normal pH of 7.4 in the blood (whereby the pK a of carbonic acid is 6.1 at physiological temperature), a 20:1 ratio of bicarbonate to carbonic acid must constantly be maintained; this homeostasis is mainly mediated by pH sensors in the medulla oblongata of the brain ...
3 (i.e. the first acid dissociation constant for carbonic acid), K 2 is the equilibrium constant for the reaction HCO − 3 ⇌ H + + CO 2− 3 (i.e. the second acid dissociation constant for carbonic acid), and DIC is the (unchanging) total concentration of dissolved inorganic carbon in the system, i.e. [CO 2] + [HCO − 3] + [CO 2− 3].
Most carbonic acid then dissociates to bicarbonate and hydrogen ions. One of the buffer systems present in the body is the blood plasma buffering system. This is formed from , carbonic acid, working in conjunction with [HCO − 3], bicarbonate, to form the bicarbonate system. [10]
The bicarbonate buffer, consisting of a mixture of carbonic acid (H 2 CO 3) and a bicarbonate (HCO − 3) salt in solution, is the most abundant buffer in the extracellular fluid, and it is also the buffer whose acid-to-base ratio can be changed very easily and rapidly. [15]
Carbonic acid is a chemical compound with the chemical formula H 2 C O 3.The molecule rapidly converts to water and carbon dioxide in the presence of water. However, in the absence of water, it is quite stable at room temperature.
In the case of citric acid, the overlap is extensive and solutions of citric acid are buffered over the whole range of pH 2.5 to 7.5. Calculation of the pH with a polyprotic acid requires a speciation calculation to be performed. In the case of citric acid, this entails the solution of the two equations of mass balance:
For example, bicarbonate (HCO 3 −) does not have a transporter, so its reabsorption involves a series of reactions in the tubule lumen and tubular epithelium. It begins with the active secretion of a hydrogen ion (H +) into the tubule fluid via a Na/H exchanger: In the lumen The H + combines with HCO 3 − to form carbonic acid (H 2 CO 3)
Recall that the relationship represented in a Davenport diagram is a relationship between three variables: P CO 2, bicarbonate concentration and pH.Thus, Fig. 7 can be thought of as a topographical map—that is, a two-dimensional representation of a three-dimensional surface—where each isopleth indicates a different partial pressure or “altitude.”