What is the thickess of diffusion membrane ?

Explanation

To answer the question about the thickness of the diffusion membrane, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Context**: The diffusion membrane is crucial for gas exchange in the lungs, specifically in the alveoli, which are the tiny air sacs where oxygen and carbon dioxide are exchanged.

2. **Identifying the Structure**: The diffusion membrane consists of three layers:
- **Squamous Epithelium**: This is the outermost layer that provides a smooth surface for gas exchange.
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