WHY THE RESPIRATORY SYSTEM?
Virtually every book on scuba diving, including the open water teaching manuals, includes some information on anatomy and physiology of the respiratory system. Why is this material important to explain scuba diving? First, because it helps explain the origin of major problems that can result from pressure - decompression sickness and air embolism. Second, because it helps explain the one process vital to every dive: breathing compressed air under water. If you already feel comfortable with basic anatomy and physiology of the respiratory system, please skip to Section D. If not, read on. (This material is germane to the rest of the book, which is why I don't put it in an Appendix.)
WHAT IS THE FUNCTION OF THE RESPIRATORY SYSTEM?
The function of the respiratory system is rather simple in concept: to bring in oxygen from the atmosphere and get rid of carbon dioxide from the blood.
Since oxygen (O2) and carbon dioxide (CO2) are gases, the process of bringing one in and excreting the other is called gas exchange.
Oxygen is necessary for normal metabolism; lack of it leads to death in a few minutes. Carbon dioxide is a waste product of metabolism; if breathing stops, carbon dioxide will quickly accumulate to a toxic level in the blood. Thus our lungs, the organs that exchange O2 and CO2 with the atmosphere, are vital since their total failure is quickly fatal.
We have two lungs, one in the right side of our chest cage and one in the left (Figure l). Between them is the heart, a midline organ that tilts slightly to the left within the chest cage. (You can feel your heart beating by placing your finger tips under your left breast.) Although gas exchange takes place in the lungs, the respiratory...