A very deep inspiration that ventilates all alveoli is called:

• A. A yawn
• B. A sigh
• C. Residual volume
• D. Tidal breathing

Answer: (A)

Verified step by step guidance

1. Understand the definitions of the terms provided in the options: A yawn, A sigh, Residual volume, and Tidal breathing.
2. Recall that a yawn is a reflex involving a deep inhalation, often associated with fatigue or boredom, but it is not specifically aimed at ventilating all alveoli.
3. Recognize that a sigh is a deep breath that occurs occasionally to reopen alveoli that may have collapsed, helping to ventilate all alveoli.
4. Understand that residual volume refers to the amount of air remaining in the lungs after a forceful exhalation, and it does not involve active ventilation of all alveoli.
5. Note that tidal breathing refers to normal, relaxed breathing, which does not involve deep inspiration to ventilate all alveoli. Based on this, identify the correct term that matches the description.