Role of the liver in AAB regulation
Oxidation of the initially underoxidized products, coming from the intestine, down to C02 and H20 is implemented in Krebs cycle under aerobic conditions. Under anaerobic conditions oxidative processesln Krebs cycle are distu rbed and a great number of "acidic" products enters a general blood flow. A metabolic acidosis develops.
The liver synthetizes urea from nitrogenous residues: ammonia NH3 and ammonium chloride NH4C1 having expressed acidic properties. A synthetized urea enters the blood flow and is excreted by the kidneys.
A part of "acidic" products is ejected with bile into GIT.
In vomiting, a loss of great amount of gastric content H+, CI" and K+ ions are being lost. A metabolic alkalosis develops.
Indices characterizing AAB:
1. pH — is a value of active reaction of blood N = 7.4 (7.35-7.45).
2. PC02 — a partial pressure of C02 in blood N = 40 mm Hg (36-44 mm Hg).
PC02 decreases in respiratory alkalosis and metabolic acidosis, and in respiratory acidosis and metabolic alkalosis PC02 elevates.
In respiratory alkalosis a decrease of PC02 is the consequence of hyperventilation as a result of which intensification of C02 removal occurs through the lungs.
In metabolic acidosis PC02 also reduces as a result of hyperventilation, but already as a compensation factor directed to the decrease of blood pH.
A rise of PC02 in metabolic alkalosis is the compensatory factor — carbon dioxide is retained in order to neutralize an excess of bases.
Elevation of PC02 in respiratory acidosis is the index of insufficiency of alveolar ventilation as a result of which an oxidation of blood advances.
A reliability of these variants is evident, but in the whole organism for a proper assessment of AAB it is necessary to determine one more index — a shift of buffer bases.
3. BE — a shift of buffer bases (an excess or deficit of bases) in the norm = 2 mmol/1.
It indicates at the etiology of AAB disorders:
— in metabolic acidosis BE (-) deficit;
— in metabolic alkalosis BE (+) excess;
— in respiratory acidosis BE (+) is insignificant;
— in respiratory alkalosis BE (-) is insignificant.
And so, (+) BE points to a shortage of nonvolatile acids or an excess of bases, and (-) BE reflects an excess of nonvolatile acids or a shortage of bases.
4. SB — a standard bicarbonate N = 20-27 mmol/1 (24 mmol/1) — it is a bicarbonate determined under standard conditions (t 37°C, pC02 40 mm Hg, Hb02= 100%).
5. AB — actual (true) bicarbonate N = 19-26 (23) mmol/1.
6. BB — a sum of bases of all buffer systems of blood N = 50 (42-60) mmol/1. In metabolic alkalosis BB is significantly greater than the norm, in respiratory acidosis BB is insignificant. The greatest decrease of BB is noted in metabolic acidosis. Insignificant decrease of BB is observed in respiratory alkalosis.
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