Mark the true statement among the following with reference to normal breathing

Options

A. Inspiration is a passive process whereas expiration is active
B. Inspiration is an active process whereas expirationis passive
C. Inspiration and expiration, both are active processes
D. Inspiration and expiration, both are possive processes

Answer

**Step-by-Step Solution:**

1. **Understanding Breathing:**
- Breathing consists of two main processes: inspiration and expiration.
- Inspiration refers to the process of taking air into the lungs (inhalation).
- Expiration refers to the process of expelling air from the lungs (exhalation).

2. **Identifying the Mechanism of Inspiration:**
- During inspiration, the diaphragm (a muscular dome located below the lungs) contracts.
- This contraction increases the volume of the thoracic cavity and the lungs, creating a negative pressure inside the lungs.
- As a result, air rushes in from the atmosphere to equalize the pressure difference.

3. **Identifying the Mechanism of Expiration:**
- During expiration, the diaphragm relaxes, which decreases the volume of the thoracic cavity and the lungs.
- This relaxation creates a positive pressure inside the lungs, causing air to be pushed out of the lungs.

4. **Defining Active and Passive Processes:**
- An active process requires energy, typically involving muscle contraction.
- A passive process does not require energy and often occurs due to natural pressure differences.

5. **Classifying Inspiration and Expiration:**
- Since inspiration involves the contraction of the diaphragm (which requires energy), it is classified as an active process.
- Expiration, on the other hand, occurs due to the relaxation of the diaphragm (which does not require energy), making it a passive process.

6. **Identifying the True Statement:**
- Based on the definitions and classifications:
- The correct statement is: "Inspiration is an active process whereas expiration is passive."

**Final Answer:**
The true statement among the options is: "Inspiration is an active process whereas expiration is passive."

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