In the ranking from most to least radiosensitive, which system is second?

In the ranking from most to least radiosensitive, which system is second?

• A. Hematopoietic
• B. Gastrointestinal
• C. Cerebrovascular
• D. Endocrine

Answer: (B)

Radiosensitivity tracks how quickly the cells of a tissue divide and how differentiated they are. Tissues with rapid cell turnover are more vulnerable to radiation. The hematopoietic system (bone marrow) is first because its cells are constantly dividing to replace blood cells, so radiation rapidly impairs blood cell production. The next most sensitive is the gastrointestinal tract, since its crypt epithelium renews itself rapidly and radiation damages those dividing cells, leading to mucosal injury. The cerebrovascular system is relatively resistant because its neurons are largely non-dividing, while endocrine glands tend to have slower turnover and are thus less sensitive than the GI tract, though they can be affected at higher doses. Therefore, the second most radiosensitive system is the gastrointestinal system.

Radiosensitivity tracks how quickly the cells of a tissue divide and how differentiated they are. Tissues with rapid cell turnover are more vulnerable to radiation. The hematopoietic system (bone marrow) is first because its cells are constantly dividing to replace blood cells, so radiation rapidly impairs blood cell production. The next most sensitive is the gastrointestinal tract, since its crypt epithelium renews itself rapidly and radiation damages those dividing cells, leading to mucosal injury. The cerebrovascular system is relatively resistant because its neurons are largely non-dividing, while endocrine glands tend to have slower turnover and are thus less sensitive than the GI tract, though they can be affected at higher doses. Therefore, the second most radiosensitive system is the gastrointestinal system.