Acid in stomach, saliva in the mouth, tears from eyes, all prevent microbial growth belong to which of the following barrier?

Options

A. Physical barrier
B. Physiological barrier
C. Cytokine barrier
D. Cellular barrier

Explanation

To solve the question regarding which barrier the acid in the stomach, saliva in the mouth, and tears from the eyes belong to, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Innate Immunity**:
- Innate immunity is the natural defense mechanism that is present in the body from birth. It includes various barriers that help prevent microbial growth and infection.

2. **Identify the Types of Barriers in Innate Immunity**:
- There are several types of barriers in innate immunity, which can be categorized into:
- Physical barriers (e.g., skin, mucous membranes)
- Physiological barriers (e.g., saliva, tears, stomach acid)
- Cellular barriers (e.g., white blood cells, monocytes, lymphocytes)
- Cytokine barriers (e.g., interferons)

3. **Analyze the Given Options**:
- The question mentions three specific substances: acid in the stomach, saliva in the mouth, and tears from the eyes.
- We need to determine which type of barrier these substances belong to.

4. **Classify the Substances**:
- **Acid in the stomach**: This is a physiological barrier as it helps to kill pathogens that enter the stomach.
- **Saliva in the mouth**: Saliva contains enzymes and antimicrobial properties that help prevent microbial growth, making it a physiological barrier.
- **Tears from the eyes**: Tears also have antimicrobial properties and help wash away potential pathogens, classifying them as a physiological barrier.

5. **Conclusion**:
- Since all three substances (stomach acid, saliva, and tears) are involved in preventing microbial growth through physiological means, they collectively belong to the **physiological barrier** of innate immunity.

### Final Answer:
The correct answer is **physiological barrier**.

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