The Respiratory System
Since gas exchange is necessary for cellular metabolism to take place, the import, transport, and export of gases is supported at several levels. In other words, oxygen and carbon dioxide molecules must pass through the tissues of many organs and several systems of your body before ever getting to the cells. The import and export of gases at the systems level is controlled by the respiratory system.
Structures and Functions of the Respiratory System
As you inhale, oxygen and other gases pass through your nose and mouth and flow toward the back of your throat. Air then enters your trachea. The trachea branches into the right or left bronchi in our lungs, which branch into narrower tubes called bronchioles. At the end of the bronchioles there are clusters of tiny air sacs called alveoli. In the alveoli is where gas exchange takes place in your lungs. As you exhale, the carbon dioxide and other gases pass through all the organs of the respiratory system until it is finally expelled out of your body.
Gas Exchange in the Lungs
Alveoli are the diffusion stations for the oxygen and carbon dioxide gas exchange needed for cellular respiration. Capillaries surround the alveoli. As we breathe in oxygen it diffuses through the alveoli membrane and into the capillaries. This allows oxygen to circulate through the body in the blood. Carbon dioxide diffuses through the capillary walls into the alveoli so it can be exhaled. This interaction between the respiratory and circulatory system keeps your cells well supplied with oxygen for ATP production and removes the carbon dioxide wastes from your body.
Systems Work Together
The act of breathing involves motor nerves that stimulate a muscle located below the lungs called the diaphragm. The change in the volume and pressure in your chest as the diaphragm contracts and relaxes is what cause your lungs to inflate and deflate.
The circulatory and respiratory systems supply all the cells with what they need. The circulatory system carries blood to all parts of the body. Blood brings nutrients and oxygen to the cells, and takes away waste which is carbon dioxide.