Describe how muscle contractions move air into the lungs
What will be an ideal response?
The lungs sit inside the ribcage in an air-filled pocket called the thoracic cavity. Forming the bottom portion of the thoracic cavity is a sheet of muscle called the diaphragm. When the diaphragm is relaxed, it is dome-shaped. When we inhale, the diaphragm contracts. This causes it to flatten, increasing the volume of the thoracic cavity. Muscles between our ribs also contract, pulling the ribcage up and out from the chest and further increasing the volume of the thoracic cavity. The volume of the thoracic cavity increases, while the amount of air inside it remains constant, causing the air pressure in the thoracic cavity to drop. Air is then sucked into the lungs, and the alveoli are filled.
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