1. parts of the body through which food passes 1 alimentary canal 2. tiny sacs within the lungs which increase the surface available for gas exchange 5 diaphragm 3. the two tubes into which the trachea divide to go into each lung 4 capillary 4. a tiny vessel through which diffusion takes place between the blood and the body tissues 6 duodenum 5. muscle below the lungs used for breathing 3 bronchi 6. the first piece of the small bowel into which the bile and pancreatic juices empty 2 alveoli