What can cause a pathological influx of water into cells?

What can cause a pathological influx of water into cells?

• A. Disruption of cell membrane permeability due to infection or injury.
• B. Excessive dehydration causes water to leave cells.
• C. Water influx only occurs with high extracellular osmolality.
• D. Active transport increases water intake.

Answer: (A)

Water moves into cells by osmosis, driven by differences in osmotic pressure across the membrane. When the cell membrane is intact, this flow is regulated. But if the membrane is disrupted by infection or injury, permeability increases and water can flood into the cell, causing swelling. This unregulated water influx is a hallmark of pathologic cell injury. Dehydration pulls water out of cells because the extracellular environment becomes more concentrated, not into cells. Water influx is not limited to situations with high extracellular osmolality; in fact, it occurs when the extracellular fluid is relatively hypotonic (lower osmolality) than the inside of the cell, driving water inward. Active transport helps move ions and solutes, but water movement itself is passive via osmosis, not directly driven by active transport.

Water moves into cells by osmosis, driven by differences in osmotic pressure across the membrane. When the cell membrane is intact, this flow is regulated. But if the membrane is disrupted by infection or injury, permeability increases and water can flood into the cell, causing swelling. This unregulated water influx is a hallmark of pathologic cell injury.

Dehydration pulls water out of cells because the extracellular environment becomes more concentrated, not into cells. Water influx is not limited to situations with high extracellular osmolality; in fact, it occurs when the extracellular fluid is relatively hypotonic (lower osmolality) than the inside of the cell, driving water inward. Active transport helps move ions and solutes, but water movement itself is passive via osmosis, not directly driven by active transport.