pH of human blood is

Appeared in: UPPSC 2017

Explanation

The normal pH of human arterial blood is maintained in a very narrow and slightly alkaline range of 7.35 to 7.45.
The value 7.4 represents the average and ideal pH for optimal functioning of enzymes and metabolic processes in the body.
This precise balance is known as acid-base homeostasis and is critical for life.
Deviations from this range can lead to severe cellular dysfunction and life-threatening conditions.

Option A: A pH of 5.4 is extremely acidic and far below the range compatible with human life. This level of acidity would cause massive protein denaturation and cell death.
Option B: A pH of 6.4 represents severe, life-threatening acidosis. The lowest pH at which a person can survive for more than a few hours is about 6.8.
Option D: A pH of 8.4 represents severe, life-threatening alkalosis. The upper limit of blood pH compatible with life for a few hours is about 8.0.

Clinical Relevance

Nursing practice connection: Knowing Normal pH of human blood helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses frequently monitor patients' acid-base status through Arterial Blood Gas (ABG) analysis, especially in critical care settings.
Understanding the normal pH range is crucial for interpreting ABG results and identifying conditions like diabetic ketoacidosis (DKA), COPD exacerbation, or kidney failure, which all disrupt acid-base balance.
What if? If a patient with DKA presents with a pH of 7.20, the nurse's priority is to administer prescribed insulin and IV fluids. The insulin helps drive glucose into cells and stops ketone production (the source of the acid), while fluids help correct dehydration and flush out ketones, both actions aimed at raising the pH back toward the normal range.

How to Approach the Question

First, identify the core concept of the question, which is the normal pH of human blood. This is a fundamental physiological value.
Recall the specific range for blood pH. The key is to remember it's slightly alkaline and very tightly controlled.
The normal range is 7.35 to 7.45. The question asks for a single value.
Evaluate the given options. 7.4 falls perfectly within the normal range and is the accepted average.
Eliminate the other options as they represent extreme and life-threatening acidosis (5.4, 6.4) or alkalosis (8.4).

Concept Tested & Keywords

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

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

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