The primary function of the respiratory system is to remove oxygen from the air and exchange it with carbon dioxide in the human lugs. The respiratory system draws air into the lungs, where it enters the alveoli. The alveoli remove oxygen from the air and insert it into the bloodstream while at the same time removing carbon dioxide from the blood, explains Merck Manual.
The respiratory system is composed of organs, tissues and muscles that enable breathing. The main parts of the system are the airways, the lungs, the alveoli and linked blood vessels, and the muscles which provide the energy for the system. The airways are pipes made of human tissue that carry air from the mouth and nose to the bronchial tubes in lungs, which distribute air throughout the two lungs. The bronchial tubes funnel the air into the alveoli. This cell tissue of the alveoli is very thin, which allows oxygen to transfer through the cell tissue into the blood vessels. The oxygen is exchanged for carbon dioxide, which the lungs remove from the blood and push up the airways out of the body, according to the National Heart, Lung and Blood Institute.
Every cell in the human body requires oxygen to live. The action of cells and muscles creates a waste product called carbon dioxide. The carbon dioxide in the body and the oxygen in the air need to be exchanged in order for the body to remain healthy. Once the alveoli exchange the oxygen for carbon dioxide in the blood, the blood passes through the blood vessels of the lung out into the general circulatory system. Capillaries, arteries and veins carry oxygen throughout the body, supplying the various organs and cells, states the American Lung Association.