1.) why does the heart rate speed up during exercise?
2.) during exercise, how does the body work to maintain homeostasis?

1.) When a man is engaged to continuous exercise or work, not only his muscles are working but also there is increase in the rate of respiration too. This accelerated rate of respiration and heartbeat provides more oxygen and food to the body. So all the organs and organ systems work in coordination. 2.) I'm sorry that I don't know the answer to your question. The one which I know, I have already written.

The molecules contain like 54 of water