The lungs provide a surface for gas exchange in mammals. Inside the lungs are the alveoli, in which oxygen dissolves into the blood. Is is basically a gas exchange.The lungs filter the heart with fresh oxygen and get it in the blood and pumped into the rest of the body until you breath out, which makes carbon dioxide!he lungs provide a surface for gas exchange in mammals. Inside the lungs are the alveoli, in which oxygen dissolves into the blood. Is is basically a gas exchange.