Analyze a real scenario, such as sprinting from a starting line, to explain how the nervous, muscular, skeletal, respiratory, and circulatory systems act together in sequence.
No single organ system produces a whole real-life action by itself. Take a sprinter reacting to a starting gun: the nervous system detects the sound almost instantly and fires signals to the leg muscles. The muscular system contracts, pulling on bones. The skeletal system provides the rigid levers those muscles pull against, plus the joints that let legs bend and swing. Almost immediately after, the respiratory system deepens and speeds up breathing, and the circulatory system raises heart rate, both rushing more oxygen to the working muscle cells.
These systems are not just happening near each other in time -- they depend on each other directly. Muscles cannot keep contracting without a steady oxygen and fuel supply from the circulatory and respiratory systems; those systems would have no reason to speed up without the nervous and muscular systems creating the demand in the first place. Studying "systems synthesis" means tracing that whole chain instead of describing each system in isolation.
Mastery looks like: They can trace a real scenario through at least three cooperating body systems, correctly noting which responds fastest and why.
Common stumbles: Describing systems as acting independently and simultaneously with no order; forgetting that circulatory and respiratory responses take a few seconds to ramp up compared to the near-instant nervous signal.