According to the New Health Guide Organization, the role the lungs play in the excretory system is to dispose of carbon dioxide through exhalation. This occurs when cells release carbon dioxide into the bloodstream. The blood then travels to the lungs where the carbon dioxide is transferred to the lungs.
According to the New Health Guide Organization, carbon dioxide is a natural bi-product of cellular respiration, which is the process by which cells produce energy using oxygen. This carbon dioxide, as a waste material, needs to be excreted from the body, which occurs through the lungs. Once the blood reaches the lungs, the alveoli in the lungs, or tiny air sacs, capture the carbon dioxide from the blood and transfer it to the lungs where it is released upon exhalation.
Other critical organs are involved in the excretory system other than the lungs, the New Health Guide Organization points out. The kidneys collect impurities from the blood in urine. Urine is then stored in the bladder until it is excreted through the urethra. The skin secretes waste products through sweat. The liver captures and breaks down toxins, and the large intestines transport the waste products, which the body excretes in the form of feces.