What is the normal range for hydrogen ion concentration (H+) in blood?

The normal range for hydrogen ion concentration in the blood is expressed as pH, which is closely related to hydrogen ion concentration. The standard pH range for arterial blood is typically between 7.35 and 7.45. To determine the corresponding hydrogen ion concentration, we can use the formula that relates pH to hydrogen ion concentration:

[

[H^+] = 10^{-\text{pH}}

]

Using this relationship, a pH of 7.40 (which is in the middle of the normal range) corresponds to a hydrogen ion concentration of about 40 nmol/L (or 40 micromoles per liter). The range of pH from 7.35 to 7.45 translates to hydrogen ion concentrations approximately between 35 and 45 nmol/L.

Therefore, the correct answer of 35-45 is consistent with the physiology of human blood hydrogen ions, aligning with expected limits for maintaining acid-base balance and homeostasis. This range reflects the normal physiological conditions under which the body regulates its metabolic processes and maintains a stable internal environment.