Gaseous Exchange PDF

Click to edit Gaseous Master title style Exchange Gaseous exchange is the process by which oxygen moves from the lungs to the blood and carbon dioxide moves from the blood to the lungs. It is a vital process that happens in the lungs between the alveoli and a network of ti...

Click to edit Gaseous Master title style Exchange Gaseous exchange is the process by which oxygen moves from the lungs to the blood and carbon dioxide moves from the blood to the lungs. It is a vital process that happens in the lungs between the alveoli and a network of tiny blood vessels called capillaries, which are located in the walls of the alveoli Capillaries cover 70% of the outside of alveoli, providing a large surface area for gases to diffuse across. 1 1 Click to edit Master title style The alveoli It is the site for gaseous exchange. Capillaries cover 70% of the outside of alveoli, providing a large surface area for gases to diffuse across. The alveoli are adapted to provide a very large surface area for gaseous exchange through the following small size - each alveolus is a small sphere about 300 μm in diameter, giving it a larger surface area to volume ratio than larger structures. The total surface area of the alveoli is around 70 square metres. number - there are around 700 million alveoli – ie 350 million per lung short diffusion path - the walls of blood capillaries and alveoli are just one cell thick. The alveoli are also lined with a thin film of moisture. Gases dissolve in this water, making the diffusion path even smaller. 2 2 Click to edit Structure of Master alveoli title style 3 3 Click to edit Master How gaseous titleoccurs. exchange style During gas exchange oxygen moves from the lungs to the bloodstream. At the same time carbon dioxide passes from the blood to the lungs. This happens in the lungs between the alveoli and a network of tiny blood vessels called capillaries, which are located in the walls of the alveoli. The walls of the alveoli share a membrane with the capillaries. This lets oxygen move from the air in the alveolus into the blood. Carbon dioxide diffuses across from the blood into the air in the alveolus. Blood containing oxygen molecules attach to red blood cells, which travel back to the heart. At the same time, the carbon dioxide molecules in the alveoli are blown out of the body the next time a person exhales. Gas exchange allows the body to replenish the oxygen and eliminate the carbon dioxide. Doing both is necessary for survival. 4 4 Click Crossto edit Master section title through thestyle alveoli showing gaseous exchange 5 5