GI Syndrome in ARS results from the death of cells in which tissue?

• A. Heart muscle
• B. Lining of the GI tract
• C. Blood vessels
• D. Lymph nodes

Answer: (B)

Damage to the rapidly renewing cells of the gastrointestinal mucosa drives GI syndrome after high-dose radiation. The lining of the GI tract is made up of epithelial cells in the crypts that constantly divide to replace old cells. When these crypt stem cells are irradiated, they die or stop dividing, the mucosa sloughs away, and the barrier function breaks down. That loss of integrity leads to severe diarrhea, dehydration, electrolyte imbalance, and the invasion of gut bacteria into the bloodstream, causing infection and systemic instability. While radiation can affect other tissues, the specific pattern of GI syndrome comes from the death of the GI mucosal lining.