Answer:
1) The air pressure in your lungs has to be less than the air outside your lungs, to get your lungs to inflate.
2) Alveolar sacs are surrounded by thin capillaries where gas can be it's changed
3) The diaphragm, located below the lungs, is the major muscle of respiration. ... Upon inhalation, the diaphragm contracts and flattens and the chest cavity enlarges. This contraction creates a vacuum, which pulls air into the lungs
4) I don't quite understand what you mean by that but I'll give it my best shot. The lungs' main role is to bring in air from the atmosphere and pass oxygen into the bloodstream. From there, it circulates to the rest of the body. The organs require help from surrounding structures in the body in order to breathe properly. The main function of the lungs is the process of gas exchange called respiration (or breathing). In respiration, oxygen from incoming air enters the blood, and carbon dioxide, a waste gas from the metabolism, leaves the blood. A reduced lung function means that the ability of lungs to exchange gases is reduced Adaptations of the alveoli: Moist walls - gases dissolve in the moisture helping them to pass across the gas exchange surface. Permeable walls - allow gases to pass through. Extensive blood supply - ensuring oxygen rich blood is taken away from the lungs and carbon dioxide rich blood is taken to the lungs.
I don't know if my 4th answer somehow gave you the answer you needed but I tried my best