Which structure are responsible for breathing process?

Options

A. larynx and bronchi
B. tracheae and alveoli
C. ribs and intercostal muscles
D. intercostal muscles and Diaphragm

Answer

To answer the question "Which structures are responsible for the breathing process?", we can break down the process of breathing into several key components and structures involved.

### Step-by-Step Solution:

1. **Understanding Breathing**: Breathing, or pulmonary ventilation, involves the movement of air into and out of the lungs. This process is essential for gas exchange, allowing oxygen to enter the bloodstream and carbon dioxide to be expelled.

2. **Inhalation Process**:
- During inhalation, the diaphragm (a dome-shaped muscle located at the base of the thoracic cavity) contracts and moves downward.
- The external intercostal muscles (located between the ribs) also contract, lifting the rib cage upward and outward.
- These actions increase the volume of the thoracic cavity, which decreases the air pressure inside the lungs compared to the outside atmosphere, causing air to rush into the lungs.

3. **Exhalation Process**:
- During exhalation, the diaphragm and intercostal muscles relax.
- The diaphragm moves back to its dome shape, and the rib cage lowers.
- This decrease in volume increases the air pressure in the lungs, forcing air out of the lungs.

4. **Key Structures**:
- The diaphragm and intercostal muscles are the primary muscles responsible for the mechanics of breathing.
- Other structures like the larynx, trachea, and bronchi are involved in the passage of air but do not actively contribute to the mechanics of breathing.

5. **Conclusion**: The structures responsible for the breathing process are the **intercostal muscles and diaphragm**.

### Final Answer:
The structures responsible for the breathing process are the **intercostal muscles and diaphragm**.

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