1. At the time of inspiration the diaphragm A.Expand B.Contract C.Relaxed D.Does not under any change
Answer: Option B Solution: When the lungs inhale, the diaphragm contracts and pulls downward. At the same time, the muscles between the ribs contract and pull upward. This increases the size of the thoracic cavity and decreases the pressure inside. As a result, air rushes in and fills the lungs.
