how do humans hearts, lungs, and circulatory system work to keepthem alive?

Answer 1

Wow, I don't know if they'd let me type 1000 pages on the subject to cover your question even close to adequately, but I'll give the Reader's Digest version a go...

The circulatory system is a liquid highway your body uses to transport oxygen and nutrients everywhere they need to go and waste products away from those tissues to be disposed. The heart is a just a positive displacement pump that keeps your blood flowing through the arteries and veins. Lungs serve as an interface between the circulatory system and the outside world, a place where oxygen can be drawn into the body through the thin membranes of the alveoli to be absorbed by red blood cells and bound by the hemoglobin molecules within, to be carried to every point in the body. The lungs are also the place where carbon dioxide, also bound by hemoglobin and brought to lungs for disposal, can pass back out and be exhaled. Much of this system is automatic and completely involuntary, and some of it isn't even controlled by the brain, at least not directly -- you can hold your breath, for instance, but you do have to consciously think about not breathing. Your brain does have some say in how fast everything works, sending a message to your heart and lungs during times of stress or exertion to say, "Hey! We're working kind of hard here; maybe we need more oxygen to the muscles! Work a little faster, please!" and you start to breathe hard and your heart starts to beat faster.

Answer 2

the heart pumps blood through the body carrying oxygen to the mucles and organs providing energy to run the body. The oxygen is given to these mucles and organs and recieves carbon dioxide to take back to the heart. Once the blood comes back to the heart it is sent through another valve of the heart to the lungs were it exchanges carbon dioxide with oxygen!