Table 1: Ph of selected fluids, organs, and membranes.

Organ, fluid or membranepHFunction of pH

(1) SkinNatural pH is between 4 and 6.5 [17]Barrier protection from microbes
(2) Urine4.6 to 8.0 [18]Limit overgrowth of microbes
(3) Gastric1.35 to 3.5Break down protein
(4) Bile7.6 to 8.8Neutralize stomach acid, aid in digestion
(5) Pancreatic fluid8.8Neutralize stomach acid, aid in digestion
(6) Vaginal fluid<4.7 [13]Limit overgrowth of opportunistic microbes
(7) Cerebrospinal fluid7.3Bathes the exterior of the brain
(8) Intracellular fluid6.0–7.2 [19]Due to acid production in cells
(9) Serum venous7.35Tightly regulated
(10) Serum arterial7.4Tightly regulated