Inspiration can occur , when -

Options

A. Pressure within the lungs is less than the atmospheric pressure.
B. Pressure within the lungs is more than the atmospheric pressure.
C. Pressure within the lungs and atmospheric air is same.
D. No effect of pressure on inspiration

Answer

**Step-by-Step Solution:**

1. **Understanding Inspiration**: Inspiration refers to the process of breathing in air. It is essential for gas exchange in the body, allowing oxygen to enter the lungs.

2. **Pressure Gradient Concept**: Inspiration occurs due to the difference in pressure between the inside of the lungs and the outside atmosphere. This concept can be illustrated with a simple analogy of two buckets of water at different levels trying to reach equilibrium.

3. **Lung Mechanics**: When we inhale, the diaphragm and intercostal muscles contract, expanding the thoracic cavity. This expansion decreases the pressure inside the lungs.

4. **Pressure Comparison**: For air to flow into the lungs, the pressure inside the lungs must be lower than the atmospheric pressure outside. This creates a pressure gradient that allows air to move into the lungs.

5. **Conclusion**: Therefore, inspiration can occur when the pressure within the lungs is less than the atmospheric pressure.

**Final Answer**: Inspiration can occur when the pressure within the lungs is less than the atmospheric pressure.

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