Answer:
A body system is a collection of parts able to work together to serve a common purpose – growth, reproduction and survival. Each part of a system depends on the other parts to perform tasks that can’t be achieved by single parts acting alone.
In fact, the human body contains trillions of cells, 78 different organs and more than 60,000 miles of blood vessels if you stretched them end-to-end. Incredibly, all of these cells, vessels and organs work together to keep you alive.
Just like how our heart, which is part of our circulatory system, does not beat unless our brain, which is part of our nervous system, tells it to. Our skeletal system is dependent on our digestive system for increase in size and strength. Our muscular system needs our respiratory and circulatory systems to supply energy in the form of oxygen and nutrients. It takes all the systems for human growth and development.
Thus, you can't have one without the other.
