Anatomy and Chemistry Basics
The Respiratory System
The function of the respiratory system is to deliver air to the lungs. Oxygen in the air diffuses out of the lungs and into the blood, while carbon dioxide diffuses in the opposite direction, out of the blood and into the lungs. Respiration includes the following processes:
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Pulmonary ventilation is the process of breathing—inspiration (inhaling air) and expiration (exhaling air).
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External respiration is the process of gas exchange between the lungs and the blood. Oxygen diffuses into the blood, while CO2 diffuses from the blood into the lungs.
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Gas transport, carried out by the cardiovascular system, is the process of distributing the oxygen throughout the body and collecting CO2 and returning it to the lungs.
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Internal respiration is the process of gas exchange between the blood, the interstitial fluids (fluids surrounding the cells), and the cells. Inside the cell, cellular respiration generates energy (ATP), using O2 and glucose and producing waste CO2.
