Which organs are listed among characteristics that determine organ sensitivity to radiation?

• A. Gastrointestinal tract organs
• B. Blood-forming organs
• C. Skin
• D. Muscle & brain

Answer: (B)

Organ sensitivity to radiation is strongly influenced by how rapidly the cells in an organ divide and renew themselves. Tissues with high cell turnover have more cells that are actively dividing, making them more vulnerable to DNA damage from ionizing radiation.

Blood-forming organs are packed with hematopoietic stem and progenitor cells that continually generate blood cells. Because these cells divide so frequently, radiation quickly impairs their ability to produce new blood cells, leading to drops in white cells, red cells, and platelets, along with immune suppression and bleeding risks. This rapid and profound impact on the marrow makes blood-forming organs among the most radiosensitive tissues, which is why they’re highlighted as a key example when discussing organ sensitivity to radiation.

In comparison, tissues like muscle and brain have low turnover and are more resistant to acute radiation effects. The skin and GI tract are also affected by radiation due to turnover, but the hematopoietic system remains the most sensitive indicator among common organ groups.