Acid-base physiology renal mechanisms

The renal mechanisms come into play immediately the disturbance of acid-base physiology starts. However, it takes a relatively long period for the renal mechanisms to come to maximum efficiency and for the renal retention of bicarbonate to build up the concentration throughout the body. In respiratory acidosis, it takes around three days for the subject to settle to the compensated point. This is where the subject then stays so long as the same degree of hypoventilation persists. 

Disorders of acid-base physiology which are not of respiratory origin are called metabolic disorders. This nomenclature derives from the fact that such disorders result from abnormal metabolism. Metabolic disorders of metabolism may also be due to excessive intake of acid or alkali or to failure of renal function, when the tubular mechanisms for formation of acid or alkaline urine are impaired. 

The explanation for the changes in extracellular hydrogen and potassium ions occurring in parallel hinges on the principle of electroneutrality. This is a constraint which applies to all systems, animate and inanimate. Despite the fact that, in the context of acid-base physiology, the principle has been applied to the kidney, the whole argument depends on the physics of the system and is independent of the details of renal mechanisms. Whatever mechanism were operating for the maintenance of ionic composition of the extracellular fluid, it would necessarily incorporate the principle of electroneutrality. 

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