Using examples how do body systems interrelate with each other?

Choose three systems and I will give you ideas.

Erm... cardiovascualr system, respiratory system and the nervous system

erm...cardiovascualr system, respiratory system and the nervous system
"erm"??

Cardiovascular system includes the blood that transports oxygen to all the organs and muscle groups in the body (and why is that important?)

Respiratory system includes the lungs that take in outside air and use the oxygen that ends up in the bloodstream (what else is there that helps besides the lungs?)

Nervous system includes the brain and spinal cord that regulate the two systems above (and how do they do that?)

Yes I have already got that information down but what I don't understand how to explain is how do they relate with each other... im finding it difficult in that

Hmm, I think you didn't see the point of wondergirl here. Look closer, you'll find a very tight relationship among the three.

Nargis, you're going to have to put in some effort here, we can't do your homework for you.

Like Unky said, it's there, you just have to look harder.