SkyMark, JetStar and others offer flights from Tokyo and other major cities in Japan to Naha. Low cost airlines such as Air Asia Japan and Peach Aviation now fly between Okinawa (Naha) and Tokyo Narita, Osaka Kansai respectively. Most Japanese airlines do offer deep discounts, but they MUST be bought in advance.
The alveoli are open to the environment so alveolar pressure (i.e. the pressure inside the lungs) is really the same as atmospheric pressure. Intrapleural pressure is the pressure of the air in the pleural cavity in which the lung sits (the space between the lung tissue and the chest wall).
There are about 300 million alveoli found in each lung of a human. The surface area resulted by alveoli for surface diffusion is about 80 m2, which is about 42 times the surface area of whole human body. The air space opening into two or more alveoli is called alveolar sac.