Although these events are rare, with the demand and availability of air travel increasing, so too is the likelihood of an in-flight emergency occurring. One of the key reasons air travel is so hard on the body is due to the cabin pressure. This pressure change has a significant impact on many body systems, especially those containing gases (such as the respiratory and gastrointestinal systems). To compensate, the body increases the number of breaths it takes. It also increases heart rate to better pump oxygen to tissues.