The normal pH of the human blood is which one of the following:
**Core Concept**
The normal pH of human blood is tightly regulated to ensure proper cellular function. This is achieved through the buffering capacity of various plasma and intracellular proteins, as well as the regulation of respiratory and metabolic processes.
**Why the Correct Answer is Right**
The normal pH of human blood is slightly alkaline, ranging from 7.35 to 7.45. This narrow pH range is crucial for maintaining proper enzyme function and preventing cellular damage. The bicarbonate buffering system plays a key role in regulating pH by binding excess hydrogen ions, thereby maintaining the delicate acid-base balance. The kidneys and lungs work together to regulate acid-base balance through the excretion of excess hydrogen ions and the production of bicarbonate ions.
**Why Each Wrong Option is Incorrect**
**Option A:** 7.0 is the pH of neutral water, but human blood is slightly alkaline, not neutral.
**Option B:** 6.5 is acidic and would indicate a severe acidosis, which is not normal.
**Option C:** 8.5 is alkaline, but not within the normal range of human blood pH.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that even a small deviation from the normal pH range can lead to significant clinical consequences, such as respiratory or metabolic acidosis, which can be life-threatening if not promptly addressed.
**Correct Answer:** C. 7.4