Worn out RBC are destroyed by `:-`

Options

A. Kupffer's cells
B. Bone cells
C. Mast cells
D. None

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the destruction of worn-out red blood cells (RBCs).

2. **Identifying the Options**: The options provided are:
- a) Kupffer cells
- b) Bone cells
- c) Mast cells
- d) Null

3. **Analyzing the First Option (Kupffer Cells)**:
- Kupffer cells are specialized macrophages located in the liver, specifically in the lining of the sinusoids (small blood vessels).
- Their primary function is to capture and destroy old and worn-out RBCs that pass through the liver.

4. **Understanding the Process of Destruction**:
- The destruction of RBCs occurs through a process called phagocytosis, where these cells engulf and break down the RBCs.
- Hemoglobin, the oxygen-carrying component of RBCs, is split into globin and heme.
- The globin chains are reused by the body, while the heme is broken down into iron and bilirubin.
- Iron can be reused for new RBC production, and bilirubin is conjugated with glucuronic acid and secreted into bile.

5. **Conclusion**: Based on the analysis, the correct answer is that worn-out RBCs are destroyed by **Kupffer cells**.

### Final Answer:
Worn out RBCs are destroyed by **Kupffer cells**.

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