What are the main functions of the cardiovascular system?

The engine...: The main function of the cardiovascular system is to keep all of the other organ systems functioning by providing them with blood flow. All the organ systems work in harmony to make the body work, some act like filters, some like computers, some like machines. The heart is like the engine in the car. You need all the parts of the car to work to drive it, but won't go anywhere without the engine.