Which of the following acts as a filter of the blood by trapping blood borne micro-organisms and also has a large reservoir of erythrocytes ?

Options

A. Bone marrow
B. Thymus
C. Spleen
D. Tonsils

Answer

To solve the question, we need to identify which of the listed organs acts as a filter for blood by trapping microorganisms and also serves as a reservoir for red blood cells (erythrocytes). Let's analyze each option step by step:

### Step 1: Analyze the Options
1. **Tonsils**:
- Function: Tonsils are lymphatic tissues located in the throat. Their primary role is to trap pathogens (like bacteria and viruses) that enter the body through the mouth or nose. However, they do not serve as a reservoir for erythrocytes.
- Conclusion: Not the correct answer.

2. **Bone Marrow**:
- Function: Bone marrow is responsible for producing blood cells, including erythrocytes, but it does not filter blood or trap microorganisms.
- Conclusion: Not the correct answer.

3. **Thymus**:
- Function: The thymus is involved in the development of T-cells, which are crucial for the immune response. It does not filter blood or serve as a reservoir for erythrocytes.
- Conclusion: Not the correct answer.

4. **Spleen**:
- Function: The spleen is the largest lymphatic organ in the body. It has two types of tissue: red pulp and white pulp. The red pulp filters out damaged or old red blood cells, while the white pulp contains immune cells (B cells and T cells) that help fight infections. Additionally, the spleen acts as a reservoir for erythrocytes.
- Conclusion: This is the correct answer.

### Final Answer:
The organ that acts as a filter of the blood by trapping blood-borne microorganisms and also has a large reservoir of erythrocytes is the **spleen**.

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