Acute radiation sickness is characterised by:
**Core Concept**
Acute radiation sickness, also known as radiation poisoning, is a medical condition that occurs when the body is exposed to a high dose of ionizing radiation, leading to damage to the bone marrow, gastrointestinal system, and central nervous system.
**Why the Correct Answer is Right**
The correct answer is **B. Hematopoietic syndrome**. This is because acute radiation sickness is primarily characterized by damage to the bone marrow, which leads to a decrease in the production of blood cells, including white blood cells, red blood cells, and platelets. This results in symptoms such as fatigue, weakness, anemia, and increased susceptibility to infections. The hematopoietic syndrome is the most common and severe form of acute radiation sickness, and it occurs at doses above 2 Gy (200 rads).
**Why Each Wrong Option is Incorrect**
**Option A:** **Gastrointestinal syndrome** is a possible manifestation of acute radiation sickness, but it is not the primary characteristic. Gastrointestinal syndrome occurs at higher doses (above 10 Gy) and is characterized by severe diarrhea, vomiting, and abdominal pain.
**Option C:** **Cardiovascular syndrome** is not a recognized manifestation of acute radiation sickness. While radiation can cause damage to the cardiovascular system, this is not a primary characteristic of acute radiation sickness.
**Clinical Pearl / High-Yield Fact**
The severity of acute radiation sickness is classified into four categories based on the dose of radiation exposure: mild (0.5-2 Gy), moderate (2-4 Gy), severe (4-6 Gy), and lethal (above 6 Gy). Understanding the dose-response relationship is crucial in managing patients with acute radiation sickness.
**Correct Answer: B. Hematopoietic syndrome**