The normal pH of blood is?

Appeared in: SCTIMST Staff Nurse - 2015 (Set-A)

Explanation

The normal pH of arterial blood is maintained in a narrow and slightly alkaline range of 7.35 to 7.45.
This specific range is critical for optimal cellular function, enzyme activity, and oxygen transport by hemoglobin.
Values below 7.35 are defined as acidosis, indicating an excess of acid in the blood.
Values above 7.45 are defined as alkalosis, indicating an excess of base in the blood.

Option A: A pH less than 7 is considered acidic. Blood is naturally slightly alkaline, not neutral or acidic.
Option B: This range (7.0 to 7.35) falls entirely within the acidotic range for blood. A pH of 7.35 is the lowest limit of normal.
Option D: While the normal range is indeed less than 7.45, this option is imprecise because it also includes the entire acidotic range (anything below 7.35). Option C provides the exact, correct range.

Clinical Relevance

Nursing practice connection: Knowing Normal blood pH range and its physiological significance helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses frequently monitor blood pH through Arterial Blood Gas (ABG) analysis, a critical diagnostic tool for assessing a patient's metabolic and respiratory status.
Abnormal pH values are a red flag for underlying diseases such as diabetic ketoacidosis, kidney failure, or severe respiratory conditions.
Prompt recognition and reporting of pH imbalances are crucial for patient safety, as they can lead to life-threatening complications if not addressed.

How to Approach the Question

This is a factual recall question that tests your knowledge of a fundamental physiological parameter.
First, identify the keywords in the question: 'normal pH' and 'blood'.
Recall that blood is slightly alkaline, meaning its pH must be just above the neutral value of 7.0.
Evaluate the options. Eliminate any that are acidic (below 7.0) or represent the acidotic range (below 7.35).
Compare the remaining options to select the one that provides the most precise and universally accepted range for normal arterial blood pH.
The range 7.35-7.45 is the standard value taught in nursing and medical physiology.

Concept Tested & Keywords

QU29hJVd5Q1wX2wIviW4_7

E6 Nursing Fundamentals Potter Perry 12e Part 5 p. 54-56

E6 Physiology Guyton 4SAE Part 2B p. 66-68

E6 Nelson Textbook of Pediatrics(2024) — Volume 1 p. 554-556

Practise the full SCTIMST Staff Nurse - 2015 (Set-A)

Attempt every question from this paper in a timed mock, then review the full solution for each one.