During severe diarrhea, which sequence best describes fluid movement?

During severe diarrhea, which sequence best describes fluid movement?

• A. Water moves from tissue to blood due to dehydration.
• B. Water moves from blood into intestinal lumen during diarrhea.
• C. Water remains in capillaries during diarrhea.
• D. Water leaks from capillaries into the intestines, increasing blood concentration, leading to a tissue-to-blood fluid shift.

Answer: (D)

During severe diarrhea, large amounts of water and electrolytes are lost into the intestinal lumen. This directly reduces the volume of fluid in the blood vessels (intravascular dehydration) and makes the remaining plasma more concentrated (hemoconcentration). The immediate movement of fluid is from the capillaries into the intestines, driven by the gradients created by fluid loss and changes in hydrostatic and oncotic pressures. As the circulating volume drops and the blood becomes more concentrated, the body shifts fluid from the interstitial tissue back into the bloodstream to help maintain perfusion—a tissue-to-blood fluid shift. This sequence—capillary leakage into the gut followed by interstitial fluid moving into the blood to compensate—best describes the fluid movement during severe diarrhea.

During severe diarrhea, large amounts of water and electrolytes are lost into the intestinal lumen. This directly reduces the volume of fluid in the blood vessels (intravascular dehydration) and makes the remaining plasma more concentrated (hemoconcentration).

The immediate movement of fluid is from the capillaries into the intestines, driven by the gradients created by fluid loss and changes in hydrostatic and oncotic pressures. As the circulating volume drops and the blood becomes more concentrated, the body shifts fluid from the interstitial tissue back into the bloodstream to help maintain perfusion—a tissue-to-blood fluid shift. This sequence—capillary leakage into the gut followed by interstitial fluid moving into the blood to compensate—best describes the fluid movement during severe diarrhea.