(1) According to the diagram, it can be seen that A represents the trachea, B represents the lungs, C represents the chest, and D represents the diaphragm.
(2) Pull down the D diaphragm with your hands, which means the diaphragm contracts and the top drops, causing the volume of the chest to increase and the air pressure in lung B to decrease, that is, the air pressure in B becomes lower, and the gas enters into B to complete the inhalation. Qi process.
(3) Letting go means that the diaphragm relaxes, its top rises, the volume of the chest cavity becomes smaller, the air pressure in the B lung increases, the gas leaves the lungs, and the exhalation process is completed.
So the answer is: (1) Lungs; chest (thoracic cage); diaphragm
(2) Increase; expand; inhale
(3) Shrink ;Exhale