How does the respiratory system change as the frog undergoes metamorphosis from a tadpole to an adult frog?
from gills to lungs
The tadpole is the aquatic larval form of the amphibian (frog in this case), a descendent of the fish which retains its gill apparatus for extacting dissolved oxygen from the water.
After metamorphosis, the frog switches over to an air-breathing lung system and hops onto the land
"The most obvious part of the amphibian metamorphosis is the  formation of four legs in order to support the body on land. But there are several other changes:  the gills are replaced by other respiratory organs, i.e., lungs,  the skin changes and develops glands to avoid dehydration,  the eyes develop eyelids and adapt to vision outside the water,  an eardrum is developed to lock the middle ear and  the tail disappears. .
How is the human respiratory system like other pneumatic systems?
the lungs work by creating a vacuum (pressure gradient) by contracting the diaphragm -- air moves in and flows through the bronchial tubes and into the alveoli. when the diaphragm releases, then air flows outward.
how it differs from a typical pneumatic system is the gas exchange that happens in the alveoli. air that comes in is a mixture of oxygen, nitrogen, co2 and other gases -- but the lungs exchange gases with your bloodstream and so the oxygen is taken into the blood and co2 released, thus you get different gases on exhalation than came in -- otherwise, you'd be dead!
How does the respiratory system contribute to the other systems?
Circulatory - Oxygen from longs pass into red blood cells (hemoglobin) to carry around the body to other organs/muscles.
Actually... thats pretty much the same for all of the systems. Oxygen. Into lungs. Into Blood. Blood carries oxygen to everything. Everything in body needs oxygen.
How is the respiratory system and circulatory system work together?
Oxygen that you breathe in gets around to all of the red blood cells in your body and helps those cells perform daily functions. So if your cells do not have oxygen then that can not do the things that help keep your heart from functioning.
How does the respiratory system connect to other bodily systems?
nervous system: there are nerves that enervate the diaphragm (and thoracic muscles), which are critical to muscular manipulation of the lung volume.
Endocrine: see renin-angiotensin system.
Excretory: perhaps the surfactant excretions that decrease surface energies, so that the lung doesn't collapse onto itself.