(a) Skin; Radiation can cause various types of injury to the akin, depending on the dose and conditions of exposure. A large dose may cause subsequent blistering and ulceration of the akin and loss of hair followed by abnormal pigmentation months or years later.
(b) Bone marrow; the blood forming cells of the bone marrow are among the most radiosensitive cell in the body. If large percentage of such cells are killed as can happen when intensive irradiation o the whole body occurs, the normal replacement of circulating blood cells is impaired as a results the blood cell count may become depressed at the end infection, hemorrhage or both may occur.
(c) Reproductive organs; Although mature spermatozoa are relatively resistant to radiation, immature sperrm forming cell are among the most radiosensitive cells in the body. Rapid exposure of both testes to even a dose may interrupt sperm production temporarily, a high dosage exposure may cause permanent sterility in men.
(d) Brain and sensory organs; Small doses of radiation can produce phosphene, a light sensation on the dark adapted retina. The mature brain and nervous system are relatively resistant to radiation injury, but the developing brain is radiosensitive to demage.
(e) Gastrointestinal track; the response of gastrointestinal track is similar in many ways to that of the skin. Proliferating cells in the nucleus membrane that lines the track are easily killed by irradiation resulting in the denudation and ulceration of the mucus membrane. If substantial portion of the small intestine is exposed rapidly to a high dose as may occur in a radiation accident a fatal dysentery like reaction results within a very short period of times.