Correct Option
The normal pH level of human blood is maintained within a narrow, slightly alkaline range of 7.35 to 7.45. This precise regulation is crucial for sustaining physiological homeostasis. The body employs multiple mechanisms to achieve this, including chemical buffer systems, respiratory regulation of carbon dioxide levels, and renal excretion or reabsorption of acids and bases. Deviations from this narrow range, leading to conditions like acidosis (pH below 7.35) or alkalosis (pH above 7.45), can severely impair cellular function and are incompatible with sustained life.
Incorrect Options
- Option (a) 4.5–46: This range includes highly acidic values (4.5) which are incompatible with human life. Such extreme acidity would lead to immediate physiological collapse.
- Option (b) 6.45–6.55: This range is significantly acidic (below 7.0) and represents a severe, life-threatening acidosis, not a normal physiological state.
- Option (d) 8.25–8.35: This range is excessively alkaline, representing a severe alkalosis that is incompatible with normal human physiological function.