7.0 is the normal pH of the:

Appeared in: AIIMS Nagpur NO- 2020

Explanation

The fluid within a typical cell, known as intracellular fluid (ICF), has a pH of approximately 7.0.
This neutral pH is slightly more acidic than blood because metabolic processes within the cell, such as glucose breakdown, produce acidic substances (e.g., carbonic acid, lactic acid).
Maintaining this specific pH is critical for the optimal function of intracellular enzymes and various cellular processes.

Option A: The pH of urine is not fixed at 7.0; it has a wide normal range from 4.5 to 8.0 to accommodate the excretion of acids or bases to maintain blood pH.
Option B: Blood in any artery, including the renal artery, is maintained in a very narrow, slightly alkaline range of 7.35 to 7.45.
Option C: Venous blood, like arterial blood, has a pH in the alkaline range, typically around 7.35. It is slightly more acidic than arterial blood due to waste CO₂ but is not neutral.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Normal pH values of various body fluids as background academic context rather than a clinical decision trigger.
Understanding the distinct pH of intracellular and extracellular fluids is fundamental to grasping acid-base balance, a critical concept in patient care.
Deviations from the normal blood pH (7.35-7.45) lead to acidosis (pH below 7.35) or alkalosis (pH above 7.45), which can impair organ function and be life-threatening. Nurses constantly monitor for signs of these imbalances.
What if? - If a patient develops diabetic ketoacidosis, their blood pH would drop below 7.35 (metabolic acidosis), and their urine pH would also become more acidic as the kidneys try to excrete the excess ketoacids.

How to Approach the Question

First, identify the core of the question: it asks for the body fluid that has a normal pH of 7.0 (neutral).
Recall the standard pH values for major body fluids.
Evaluate Option A (Urine): Remember that urine pH is highly variable and not fixed.
Evaluate Option B and C (Blood): Recall that blood pH (both arterial and venous) is tightly controlled in a slightly alkaline range (7.35-7.45). A pH of 7.0 would be a severe acidosis.
Evaluate Option D (Intracellular fluid): Recall that the fluid inside cells is slightly more acidic than blood due to metabolism, with a textbook value around 7.0.
Conclude that intracellular fluid is the correct match for a normal pH of 7.0.

Concept Tested & Keywords

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

E6 Nursing Fundamentals Taylor p. 785-787

Practise the full AIIMS Nagpur NO- 2020

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