Gastrointestinal Changes
If an individual receives 600-800 rad of acute radiation dose, damage to the stomach lining and/or intestine may occur. The high doses of radiation may cause structural changes to the gastrointestinal tract including decreased absorption, ulceration, and dehydration. If the individual suffers from severe infection, fluid loss, blood loss, or circulatory collapse, death may occur within seven days.
schematic of gastrointestinal system.