The alveoli are found in the lungs, which are the organs responsible for gas exchange in the human body. Alveoli are tiny air sacs located at the end of the bronchial tubes, and they facilitate the transfer of oxygen and carbon dioxide between the lungs and the bloodstream. This process is crucial for respiration, allowing oxygen to enter the blood while simultaneously removing carbon dioxide. The alveoli have a large surface area and are surrounded by capillaries, making them very efficient at gas exchange, which is vital for sustaining life.