The normal blood pH range is:

Appeared in: Bihar NHM CHO-2025

Explanation

The normal pH of adult arterial blood is maintained within a very narrow range of 7.35 to 7.45.
This slightly alkaline environment is crucial for optimal cellular function, enzyme activity, and the proper transport of oxygen by hemoglobin.
The body's acid-base homeostasis is managed by chemical buffers, the respiratory system (regulating CO2), and the renal system (managing bicarbonate and H+ ions).
Values outside this range indicate either acidosis (too acidic) or alkalosis (too alkaline), which can lead to severe physiological problems.

Option B: This range (6.8-7.0) represents severe, life-threatening acidosis. A pH of 6.8 is considered the lower limit compatible with life for more than a few hours.
Option C: This range (7.5-7.8) indicates significant to severe alkalosis. A pH level of 7.8 is considered the upper limit compatible with life.
Option D: This range (7.0-7.2) indicates significant acidosis. While not as immediately fatal as a pH below 7.0, it is a serious condition that requires urgent medical intervention to prevent progression to coma or death.

Visual 1: Diagram: A pH scale from 0 to 14, clearly marking the narrow window for normal blood pH (7.35-7.45). The diagram should also label the ranges for acidosis (below 7.35) and alkalosis (above 7.45) to provide a visual context for acid-base balance.

Clinical Relevance

Nursing practice connection: Knowing Normal blood pH and acid-base balance helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Monitoring blood pH through Arterial Blood Gas (ABG) analysis is a fundamental nursing assessment, especially in critically ill patients, to guide treatment for acid-base imbalances.
Nurses must be able to recognize the clinical manifestations of acidosis (e.g., lethargy, confusion, Kussmaul respirations) and alkalosis (e.g., irritability, muscle cramps, paresthesia) for early detection and intervention.
What if? A patient with chronic obstructive pulmonary disease (COPD) has a pH of 7.32 (mild respiratory acidosis). The nurse's priority would be to assess respiratory status and improve ventilation, as this is the root cause, rather than administering bicarbonate, which would not correct the underlying respiratory problem.

How to Approach the Question

This is a factual recall question that tests your knowledge of a core physiological value.
First, identify the key terms in the question: 'normal blood pH'.
Recall the specific, narrow range that the body maintains for homeostasis.
Compare your recalled range (7.35-7.45) with the options provided.
Eliminate the options that fall outside this normal range, as they represent pathological states of acidosis or alkalosis.

Concept Tested & Keywords

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E6 Textbook of Biochemistry for medical Students 11th Edition DM Vasudevan Part 2 — Subpart A (pp 1-239 of 478) p. 239-478

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