Inspiration occurs when

Options

A. Intrapulmonary pressure `gt` Atmospheric pressure
B. Intrapulmonary pressure `lt ` Atmospheric pressure
C. Intrapulmonary pressure = Atmospheric pressure
D. Atmospheric pressure `gt`= Intrapulmonary pressure

Answer

**Step-by-Step Solution:**

1. **Understanding Inspiration:**
- Inspiration is the process of taking air into the lungs. It is essential for gas exchange, allowing oxygen to enter the bloodstream.

2. **Pressure Concepts:**
- There are two key pressures to understand: intrapulmonary pressure (pressure within the lungs) and atmospheric pressure (pressure of the air outside the body).

3. **Pressure Gradient:**
- Air moves from areas of higher pressure to areas of lower pressure. Therefore, for air to flow into the lungs, the pressure inside the lungs (intrapulmonary pressure) must be lower than the pressure outside (atmospheric pressure).

4. **Analyzing the Options:**
- Option A: Intrapulmonary pressure is greater than atmospheric pressure - This would prevent air from entering the lungs.
- Option B: Intrapulmonary pressure is less than atmospheric pressure - This allows air to flow into the lungs, making this the correct answer.
- Option C: Intrapulmonary pressure equals atmospheric pressure - This would mean no air movement.
- Option D: Atmospheric pressure is greater than or equal to intrapulmonary pressure - This does not specify the necessary condition for inspiration.

5. **Conclusion:**
- Therefore, inspiration occurs when the intrapulmonary pressure is less than the atmospheric pressure. The correct answer is Option B.

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