The picture below shows the teaching aid of the relationship between diaphragm movement and respiratory movement. Please answer the following questions according to the picture: (1) The balloon in the picture represents _ _
(1) Pulmonary thoracic diaphragm
(2) Enlargement? Decreased contraction? Contraction? Expand expansion? Reduce
(3) Because bacteria and viruses can spread from bronchi to lungs, causing pneumonia.