Once they reach the organ they deliver much needed oxygen and take away carbon dioxide and other waste products that the body cannot use. This must be done without interruption to remain healthy and sustain life. Every living cell in the body depends on oxygen for life. Any cell deprived of oxygen for more than thirty minutes will die. The cells in the brain are even more dependent on fresh oxygen. If the brain cells are deprived of oxygen for five seconds it can cause unconsciousness to occur. If the brain is deprived for more than four minute

s it will die. But, where does all this oxygen come from, the lungs.

Unlike the heart, which is made entirely of muscle, the lungs have no muscles in them. They are forced to expand and allowed to contract through the movements of the ribs and the diaphragm. Like your heartbeat, the rhythmic motion of your lungs expanding and relaxing is a constant process. You can however control your breathing to a certain extent. For instance, if you feel like taking a deep breath you can do so instantly. But you cannot make your heart faster or slower on impulse. You have the power to hold your breath, but only for a short period of time. If you hold your breath long enough you will fall into un consciousness and then resume breathing automatically. “ The reason behind this si that the muscles that control your breathing are controlled by your body’s nervous system”(Dunbar5). If the brain sees there is not enough oxygen supplied to the brain the body will be forced to breath so life can be sustained.

The lungs, I believe, are the second most important organ in the circulatory system, For one reason they are the only way for oxygen to be received into the body. It is in the lungs that cells absorb fresh oxygen, and where carbon dioxide is released to be expelled from the body. The transfer of these two gasses takes place in the alveoli in the lungs. “Alveoli are ‘small

Some topics in this essay:
G-2 Blood, , tricuspid valve, oxygen carbon dioxide, lungs left heart, circulatory system, carbon dioxide, oxygen carbon, left heart, lungs left, organ circulatory system, cava carries blood, hold breath, pulmonary arteries, contracts squeezing blood, leads lungs, pulmonary artery,