Which one of the following act as soldiers in human body?

Options

A. Monocytes
B. Lymphocytes
C. Erythrocytes
D. All of these

Answer

**Step-by-Step Solution:**

1. **Understanding Blood Composition**: Blood is composed of two main components: plasma and formed elements. Plasma is the liquid part, while formed elements include various types of cells.

2. **Identifying Formed Elements**: The formed elements consist of three main types of cells:
- Red Blood Cells (RBCs or erythrocytes)
- White Blood Cells (WBCs or leukocytes)
- Platelets (thrombocytes)

3. **Role of Red Blood Cells**: RBCs are primarily responsible for transporting oxygen throughout the body. They do not play a role in the immune response.

4. **Role of White Blood Cells**: WBCs are crucial for the immune system, providing protection against infections and foreign substances. They are further classified into two categories:
- Granulocytes (which contain granules in their cytoplasm)
- Agranulocytes (which do not contain granules)

5. **Subcategories of White Blood Cells**:
- Granulocytes include neutrophils, eosinophils, and basophils.
- Agranulocytes include lymphocytes and monocytes.

6. **Function of Monocytes**: Monocytes are phagocytic cells that directly engulf bacteria and foreign substances. They play a direct role in the immune response.

7. **Function of Lymphocytes**: Lymphocytes are involved in the immune response by producing antibodies. They are divided into B-lymphocytes and T-lymphocytes, but their action is more indirect compared to monocytes.

8. **Conclusion**: Since monocytes directly engage in the immune response by engulfing pathogens, they can be considered the "soldiers" of the human body. In contrast, lymphocytes, while important, act indirectly through antibody production.

**Final Answer**: Monocytes act as soldiers in the human body.

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