Question

In which cell, mitochondria occupies more volume in cytoplasm?

• A. Smooth muscle cells
• B. White skeletal muscle cells
• C. Cardiac muscle cells
• D. Red blood cells (RBC)

Hint:

The heart has an absolute requirement for aerobic metabolism. This explains why cardiac muscle cells have a very high mitochondrial volume and are highly sensitive to oxygen deprivation (ischemia).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Mitochondria are the "powerhouses" of the cell, responsible for producing ATP through aerobic respiration.
Cells with high, continuous energy demands require a larger volume of mitochondria in their cytoplasm.

Step 2: Detailed Explanation:
Let us compare the mitochondrial volume in different cells:
- Red Blood Cells (RBCs): Mature mammalian RBCs lack mitochondria entirely to prevent them from consuming the oxygen they transport. Their mitochondrial volume is \(0\%\).
- White Skeletal Muscle Cells: These cells are adapted for short, rapid bursts of activity using anaerobic glycolysis. They have relatively few mitochondria.
- Smooth Muscle Cells: These cells contract slowly and have low, steady energy requirements, requiring a low mitochondrial density.
- Cardiac Muscle Cells: The heart must contract continuously and rhythmically without resting throughout the animal's life. It relies almost entirely on aerobic oxidative metabolism.
To meet this high, constant energy demand, mitochondria occupy a large portion of the cytoplasm in cardiac muscle cells, typically \(35\%\) to \(40\%\) of the cell volume.
This is the highest mitochondrial volume density of any cell type in the body.

Step 3: Final Answer:
Mitochondria occupy the most volume in the cytoplasm of Cardiac muscle cells.