The Human Respiratory System · NCERT Biology

During expiration, the diaphragm and external intercostal muscles ________, and the diaphragm becomes ________.

  1. Contract, flat
  2. Relax, dome-shaped
  3. Contract, dome-shaped
  4. Relax, flat
Show answer and explanation

Correct answer: Relax, dome-shaped

Relaxation of the diaphragm and the intercostal muscles returns the diaphragm and sternum to their normal positions and reduces the thoracic volume. The diaphragm returns to its original dome-shaped position during expiration.

Difficulty: Medium Question 19 of 20

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