The most metabolically active organ of the body is:

Appeared in: IGNOU PB Bsc Nsg.Entrance-2026

Explanation

The heart is the correct answer because it has the highest energy demand among the options due to its continuous, non-stop mechanical pumping action.
According to biochemical data, the heart consumes about 6 kg of ATP daily, which is 20 to 30 times its own weight, a rate higher than any other organ.
The heart's energy is primarily derived from the oxidative metabolism of fatty acids (60-90%) and, to a lesser extent, glucose (10-40%).

Option B: Although the brain consumes a large fraction of the body's total glucose (60%) and oxygen (20%), its metabolic rate per gram of tissue is lower than the heart's.
Option C: The stomach's metabolic rate is variable and peaks only during the process of digestion. It does not have the continuous high energy demand seen in the heart.
Option D: The pancreas has important secretory functions (enzymes, hormones) that require energy, but its overall metabolic rate is significantly lower than the heart's continuous mechanical work.

Clinical Relevance

Nursing practice connection: Knowing Metabolic activity of major organs helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
The heart's extremely high metabolic rate and dependence on oxygen make it highly vulnerable to ischemia (reduced blood flow).
In conditions like coronary artery disease, a blockage can quickly lead to myocardial cell death (heart attack) because the energy supply cannot meet the immense demand.
What if? If a patient is in septic shock, the metabolic demands of all organs, including the heart, increase dramatically. This can lead to cardiac dysfunction if oxygen delivery is compromised, highlighting the need for aggressive resuscitation and oxygen support.

How to Approach the Question

First, identify the core of the question, which is to find the organ with the highest metabolic activity (energy consumption rate).
Consider the function of each organ listed in the options.
Compare the nature of their work: Is it continuous or intermittent? Is it mechanical, electrical, or chemical?
The heart performs continuous, high-intensity mechanical work (pumping blood). The brain performs continuous electrochemical work. The stomach and pancreas have more intermittent, digestive/secretory functions.
Recall or deduce that continuous mechanical work on a large scale, like the heart's, requires the most significant and constant energy supply per unit of mass.
Therefore, select the heart as the most metabolically active organ among the choices.

Concept Tested & Keywords

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E6 Textbook of Biochemistry for medical StudentsDM Vasudevan Part 1 (pp 26-370 of 370) p. 340-342

E6 Biochemistry U Satyanarayana— Part 1 (pp 26-420 of 840) p. 387-389

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