Boyle’s law states that the pressure in an enclosed gas is inversely related to its volume. Which of the following descriptions is compatible with Boyle’s law and with respiratory physiology? A. As the sternum and ribs move outward, the volume of the chest increases. This causes an increase in the enclosed air pressure. Hence air is exhaled along the pressure gradient. B. Bronchodilation expands the volume enclosed by the bronchioles. This decreases the air pressure within them and so atmospheric air moves into the lungs along the pressure gradient. C. Diffusion of oxygen from alveolar air into the blood decreases the partial pressure of oxygen in the lungs. This decreased pressure allows atmospheric air to enter the lungs along the pressure gradient. D. As the diaphragm moves down, the chest volume expands which decreases the pressure in that volume. Consequently atmospheric air is forced into the lungs along the pressure gradient.
Option D. As the diaphragm moves down, the chest volume expands which decreases the pressure in that volume. Consequently atmospheric air is forced into the lungs along the pressure gradient.
