Heparin, histamine, and serotonin are secreted by

Options

A. Lymphoid cells
B. Mast cells
C. Fibroblasts
D. Macrophages

Answer

To answer the question "Heparin, histamine, and serotonin are secreted by," we will go through the following steps:

### Step-by-Step Solution:

1. **Identify the Substances**: The question asks about three specific substances: heparin, histamine, and serotonin.

2. **Understand Their Functions**:
- **Heparin**: It is an anticoagulant that prevents blood clotting.
- **Histamine**: It is involved in local immune responses and regulates physiological functions in the gut.
- **Serotonin**: It is a neurotransmitter that contributes to feelings of well-being and happiness.

3. **Locate the Source**:
- These substances are secreted by specific cells in the body.

4. **Identify the Correct Cell Type**:
- The options provided are:
- A) Lymphoid cells
- B) Mast cells
- C) Fibroblast
- D) Macrophages
- Among these, mast cells are known to secrete heparin, histamine, and serotonin.

5. **Confirm the Tissue Type**:
- Mast cells are found in areolar tissue, which is a type of loose connective tissue. Areolar tissue serves as a framework and support for organs.

6. **Conclude the Answer**:
- Therefore, the correct answer to the question is option B: Mast cells.

### Final Answer:
Heparin, histamine, and serotonin are secreted by **Mast cells** (Option B).

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