Circulatory system?

How do the digestive, respiratory and circulatory system interact with one another?

• The respiratory system, circulatory system and the digestive system

• Answer:

  The digestive system is how you process all the food you eat - it goe through the stomach to kil at the germs and get churned up, then all the digestive enzymes are secreted as it leaves. The enzymes break the big molecules down into smaller more easily absorbed molecules, which are then absorbed into the circulatory system via microvilli in the small intestine. Things such as glucose,small molecules of fat and amino acids go to different areas throughout the body, acting as fuel for the body. The respiratory system provides oxygen, which is needed mainly to break down the glucose, or more specifically the oxygen molecules act as a donor for H+ molecules once glucose has been broken down, and the carbon dioxide is removed via the respiratory system, another bi-product of metabolism.