Okay so we just covered the skeletal system. In essence, this systems function is the framework for the entire body. It protects the internal organs. For example the rib cage protects many vital organs like the heart and lungs. Without the rib cage protecting those organs they may be more susceptible to damage caused by rigorous motions. The integumentary system also works in protecting the body. Basically this system is an organ all in itself– the skin! The integumetary system protects the body by keeping toxins out, blood in, working as pain receptors, keeping temperature constant, and much more! This system protects the body physically, (as a barrier for scrapes etc) but also chemically (water balances, sweat, and mineral balance). Along with both of these systems protecting the body also comes the instability that happens with imbalance. If the systems happen to be imbalance many diseases can happen. For example, osteoporosis for the skeletal system, and herpes for the integumentary system!
In case you need help with each system here are some links!