Summary of the roles of the digestive and respiratory system and how they related to each other and the circulatory system.

Role of the Digestive system
The digestive systems are the organs that aid the breakdown of ingested food into usable compounds for metabolic and growth. The function of the digestive system is to break down the food we eat into small part so that the body can use them to build and nourish cell and provide energy.
The food that is eaten does in through the mouth and must be moved through the digestive tract to be broken down. The digestive system contains glands produce enzymes to aid in the digestion. The Digestive system is also responsible for absorbing the nutrients. The absorption takes place in the small intestine which contains Villi, it increase the surface area allowing more nutrients to be absorbed.
The stomach and small intestine produce hormones which control the function of the digestive system. The production of stomach acid is necessary for the growth of cells in the lining of the stomach. The nerves both inside and outside the digestive system helps to regulate the functions of the digestive system.

Roles of the Respiratory system
The primary function of the respiratory system is to exchange gases. Oxygen is inhaled so the blood can carry it to the parts of the body, and carbon dioxide, a waste product, is breathed out

The role of the respiratory system is the exchange of gases such as oxygen and carbon dioxide in the lungs. The structures comprising the respiratory tract play a necessary role in the function of the system. The upper respiratory tract is a passageway for oxygen and carbon dioxide during breathing process. The