1. The heart pump oxygenated blood from the lungs to the body and deoxygenated blood out of the body in a continuous, coordinated cycle
2. The villi contains cells that produce digestive enzymes that chemically break down the nutrients for the absorption and mix with blood.
3. The kidney removes waste products in the blood and excretes the waste in the form of urine.
4. The brain tells the stomach, intestines, and liver when to be active and when to rest. Messages to and from the brain decide when it's time to process food.
5. Blood cells are produced in the bone marrow.
6. These two systems provide a framework and support movement.
7. Nerves send messages to muscles to tell them how and where to move. Nerves check up on the body's need for oxygen in the muscles and adjust breathing rate and heart rate as needed.​