The muscular system can be broken down into three types of muscles: skeletal, smooth and cardiac, according to the NIH. Skeletal muscles are the only voluntary muscle tissue in the human body and control every action that a person consciously performs. The muscle that is found at the heart is Cardiac Muscle. It is an involuntary, striated muscle that constitutes the main tissue of the walls of the heart. Hope this helps.
They work together to give the cells the ingredients they need to produce energy.
Sedimentary, okay hope i helped
A good topic idea that could be used can be about ecosystems. Such as how geographic area, plants, animals, weather and landscape make up the types of organisms in that specific ecosystem.