How do your observations of the marshmallows relate to pulmonary ventilation? When you contract your external intercostal and diaphragm muscles, the volume of your chest cavity decreases and the alveolar

pressure increases. Atmospheric pressure is then lower than alveolar pressure and air enters the lungs. When you contract your external intercostal and diaphragm muscles, the volume of your chest cavity and the alveolar pressure both decrease. Atmospheric pressure is then higher than alveolar pressure and air enters the lungs. When you contract your external intercostal and diaphragm muscles, the volume of your chest cavity and the alveolar pressure both increase. Atmospheric pressure is then lower than alveolar pressure and air enters the lungs. When you contract your external intercostal and diaphragm muscles, the volume of your chest cavity increases and the alveolar pressure decreases. Atmospheric pressure is then higher than alveolar pressure and air enters the lungs.