[Acid-base regulation: a general introduction].
Acid-base homeostasis of the body fluid in all the animal species including humans is now recognized to be kept at 0.6-0.7 unit higher than neutral pH (pN). This concept is called relative constant alkalinity. It has also found that intracellular pH is approximately kept at pN, so that the difference between extracellular (pHo) and intracellular pH (pHi) is again 0.6-0.7. Since pN increases about 0.016 unit/1 degree C with decreasing temperature, normal blood pH at 20 degrees C is about 7.7 in cold-blooded animals as well as in humans with low temperature e.g. during special operative procedure. The main physiological significance for maintaining pHi at pN is that ionized small molecules in the cell are held within the intracellular space and metabolic process can be proceeded smoothly.
Honda
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Department of Physiology, School of Medicine, Chiba University.
D000136:Acid-Base Equilibrium; D000818:Animals; D006706:Homeostasis; D006801:Humans