The circulatory system works with the respiratory system to get both blood and oxygen all throughout the body. Our blood requires oxygen so we may have what we need in our body. 

The skeletal system gives our respiratory system protection. The bones in nasal cavity is what's responsible for it having two sides (nostrils). The bones also give us soft tissue in the upper tract. 

In frogs not only do they breathe with their lungs but they also are able to breathe through pores in their skin.

2 Medical Problems w/ system 

With the urinary system (aka the renal system) it's main functions are producing, store and eliminating the waste in our bodies.

The Urinary system works with both the respiratory system and the integumentary system  to  take in substances our body needs and balances all of it out. Distributes what is needed throughout the body and whatever isn't needed is secreted out. EX: water and certain chemicals.

Both Humans and Frogs both have kidneys and a bladder BUT a frog has a special organ with their urinary system. The Cloaca, it simply takes liquid AND solid waste together and disposes of them at the same time... ew.

The digestive system realistically can go with any other body system due to it being the source of our fuel in our entire body. But the circulatory system is very closely related to the digestive system, the  nutrients we will obtain from digestion practically go straight into the circulatory system so the nutrients can be absorbed almost right away. the obvious system that works closely with the digestive is the excretory system. It is how we get rid of all the unneeded nutrients and leftover food in our body, more specifically the stomach and intestines.

Overall frogs and humans have a similar digestive system. BUT frogs actually have two sets of teeth compared to the one set in humans. Also an obvious difference is the size and length of the organs (frogs are much smaller). Unlike us, Frogs do not have an appendix and their tongues are connected directly to the starting point of the mouth.