Life span of platelets is `:-`

Options

A. 4 days
B. 9-12 days
C. 20-30 days
D. 90 days

Answer

**Step-by-Step Solution:**

1. **Understanding Platelets**: Platelets, also known as thrombocytes, are small cell fragments in the blood that play a crucial role in blood clotting.

2. **Origin of Platelets**: They are derived from larger cells called megakaryocytes, which are found in the bone marrow. When megakaryocytes break apart, they release platelets into the bloodstream.

3. **Function of Platelets**: The primary function of platelets is to prevent bleeding by forming clots at the site of injury. A low platelet count can lead to excessive bleeding.

4. **Lifespan of Platelets**: The lifespan of platelets in the bloodstream is approximately 9 to 12 days. This is the time during which they remain functional before they are removed from circulation.

5. **Destruction of Old Platelets**: Old or worn-out platelets are destroyed through a process called phagocytosis, which primarily occurs in the spleen and liver. These organs are responsible for filtering out and breaking down old blood cells.

6. **Mechanism of Phagocytosis**: The process of phagocytosis of old platelets is regulated by an internal apoptotic mechanism, which ensures that only the old or damaged platelets are removed from circulation.

7. **Conclusion**: Based on the information gathered, the lifespan of platelets is confirmed to be 9 to 12 days. Therefore, the correct answer to the question is 9 to 12 days.

**Final Answer**: The lifespan of platelets is 9 to 12 days.

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