Oxygen is essential to human bodies for survival because it provides nutrients that are then transported throughout the body by the blood. Oxygen reaches human bodies through the air before being broken down and transported.
The respiratory and cardiovascular systems are responsible for the processing and transportation of oxygen in the human body. The respiratory system begins by taking in oxygen through the nasal cavity during breathing. The inhaled air continues through the respiratory system, passing through the bronchi and reaching the lungs. As the primary organ of this system, the lungs diffuse air and separate the oxygen from the other elements. An important transfer takes place as oxygen binds to the hemoglobin in the red blood cells, and carbon dioxide is released and later exhaled. These cells are forced to become more efficient in environments where oxygen is less available, such as at high altitudes.
Once the cells are oxygen-enriched, the cardiovascular system takes over by transporting the cells throughout the body. This process begins as the oxygenated blood enters the left side of the heart and is pumped through a series of arteries that feed the individual cells. Once the nutrients are passed on, the blood returns to the heart through a series of veins, and the process is repeated.