Help with discusion!

There are two parts to this discussion:

Part One:
As eluded to in the Module Preview, aircraft pressurization systems are critical component in the world of flight physiology. With this in mind, compare and contrast two different types of aircraft pressurization systems. Discuss the key components and how a failure of any of these components could result in a physiological insult to an aviator.

Part Two:
Your next set of discussion questions examines a byproduct of aircraft pressurization - cabin altitude. What is cabin altitude? Why is it important in flight physiology? What is the typical cabin altitude of a commercial airliner? Does this altitude typically pose a problem to the passenger?