Table 1.

Ph of selected fluids, organs, and membranes.

Organ, fluid or membrane	pH	Function of pH
(1) Skin	Natural pH is between 4 and 6.5 [17]	Barrier protection from microbes
(2) Urine	4.6 to 8.0 [18]	Limit overgrowth of microbes
(3) Gastric	1.35 to 3.5	Break down protein
(4) Bile	7.6 to 8.8	Neutralize stomach acid, aid in digestion
(5) Pancreatic fluid	8.8	Neutralize stomach acid, aid in digestion
(6) Vaginal fluid	<4.7 [13]	Limit overgrowth of opportunistic microbes
(7) Cerebrospinal fluid	7.3	Bathes the exterior of the brain
(8) Intracellular fluid	6.0–7.2 [19]	Due to acid production in cells
(9) Serum venous	7.35	Tightly regulated
(10) Serum arterial	7.4	Tightly regulated