Question

Which flexible flattened muscle helps the lungs in moving air into and out of them?

• A. Pharynx
• B. Larynx
• C. Alveoli
• D. Diaphragm

Hint:

Breathing muscles:
• Diaphragm \( \rightarrow \) Main respiratory muscle
• Intercostal muscles \( \rightarrow \) Assist breathing

Answer 1

The Correct Option is D

Concept:
Breathing involves movement of air into and out of lungs. The main muscle responsible for breathing is the: \[ \boxed{\text{Diaphragm}} \] The diaphragm is:
• Thin
• Flexible
• Dome-shaped muscular sheet It separates: \[ \text{Thoracic cavity and abdominal cavity} \]

Step 1: Understand inhalation.
During inhalation:
• Diaphragm contracts
• Moves downward
• Chest cavity volume increases As a result: \[ \text{Air enters lungs} \]

Step 2: Understand exhalation.
During exhalation:
• Diaphragm relaxes
• Moves upward
• Chest cavity volume decreases Thus: \[ \text{Air moves out of lungs} \]

Step 3: Analyze all options carefully.
Option (A): Pharynx
Passage for food and air. Incorrect. Option (B): Larynx
Voice box. Incorrect. Option (C): Alveoli
Site of gas exchange. Incorrect. Option (D): Diaphragm
Main breathing muscle. Correct.

Step 4: Select the correct answer.
Therefore, the flexible flattened muscle helping lungs in breathing is: \[ \boxed{\text{Diaphragm}} \] Hence, \[ \boxed{(4)\ \text{Diaphragm}} \]