bloodstream
left The human respiratory system is only part of the story of respiration. Diaphragm, lungs, and trachea take air deep into the body and provide oxygen gas to the bloodstream. The fate of that oxygen is the story of cellular respiration. center Spiracles in this Cluentius Sphinx Neococytius cluentius caterpillar connect to a system of internal tubes tracheae , which carry oxygen throughout the animal's body. right Gills in this alpine newt larva, Ichthyosaura alpestris , bring blood close to an extensive surface area so that the newt can absorb dissolved oxygen gas from its watery habitat.