Which tissue is the most radiation-sensitive?

Which tissue is the most radiation-sensitive?

• A. Central nervous system
• B. GI tract
• C. Bone marrow
• D. Skin

Answer: (C)

Radiosensitivity is highest in tissues with many actively dividing, undifferentiated cells. Bone marrow is packed with hematopoietic stem cells that are constantly proliferating to maintain blood cell production, making them extremely vulnerable to DNA damage from ionizing radiation. That rapid cell turnover drives bone marrow to be the most radiation-sensitive among the options. The central nervous system, by contrast, contains largely mature, nondividing cells and is relatively resistant to radiation. The GI tract has rapidly dividing mucosal cells and is sensitive, but overall it tends to be less sensitive than bone marrow. The skin has renewable basal cells, giving some radiosensitivity, but not at the level of bone marrow.

Radiosensitivity is highest in tissues with many actively dividing, undifferentiated cells. Bone marrow is packed with hematopoietic stem cells that are constantly proliferating to maintain blood cell production, making them extremely vulnerable to DNA damage from ionizing radiation. That rapid cell turnover drives bone marrow to be the most radiation-sensitive among the options. The central nervous system, by contrast, contains largely mature, nondividing cells and is relatively resistant to radiation. The GI tract has rapidly dividing mucosal cells and is sensitive, but overall it tends to be less sensitive than bone marrow. The skin has renewable basal cells, giving some radiosensitivity, but not at the level of bone marrow.