Explain how the human body is adapted for gas exchange

Gas exchange occurs in the lungs where oxygen enters from the air and diffuses into the blood stream and carbon dioxide in moves the opposite direction. Oxygen is needed for respiration by the body, for example for aerobic respiration in the muscles, which produces carbon dioxide as a waste product.Lungs have a large surface area to volume ratio due to the branching bronchi with alveoli at the end of bronchioles. These alveoli are well adapted for efficient gas exchange due to their large surface area, their elastic recoil (to allow rapid exhalation), and their moist surface (to stop them sticking together and drying out). The alveoli wall is 1 cell this so there is a short diffusion distance between the air and blood, this allows rapid exchange of CO2 and O2 gases. A steep concentration gradient also helps diffusion from a high to a low concentration, for example oxygen moving from the air to the blood. Many thin capillaries surround alveoli, these narrow vessels force red blood cells to pass 1 cell at a time to allow maximum time for gas exchange to occur. Red blood cells are concave, bendy and contain no nucleus to allow them to carry as much oxygen as possible.