What happened when the intrapulmonary pressure is less than atmospheric pressure ?

Options

A. Inspiration
B. Expiration
C. Emphysema
D. Forceful expiration

Answer

To solve the question "What happens when the intrapulmonary pressure is less than atmospheric pressure?", we can follow these steps:

### Step 1: Understand Intrapulmonary Pressure
Intrapulmonary pressure refers to the pressure within the lungs (pulmonary cavity). Atmospheric pressure is the pressure exerted by the weight of the air outside the body.

### Step 2: Compare Intrapulmonary Pressure and Atmospheric Pressure
When the intrapulmonary pressure is less than atmospheric pressure, it indicates that the pressure inside the lungs is lower than the pressure outside the body.

### Step 3: Air Movement
According to the principles of gas laws, air moves from areas of higher pressure to areas of lower pressure. Therefore, if the pressure inside the lungs is lower than that outside, air will flow into the lungs.

### Step 4: Inspiration
The process of air flowing into the lungs due to the pressure difference is called inspiration (or inhalation). This is the primary action that occurs when intrapulmonary pressure is less than atmospheric pressure.

### Step 5: Conclusion
Thus, when the intrapulmonary pressure is less than atmospheric pressure, it leads to inspiration, where air is drawn into the lungs.

### Final Answer
When the intrapulmonary pressure is less than atmospheric pressure, inspiration occurs as air flows into the lungs.

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