1. What Are Body Systems? The single cell from which a baby is born ultimately divides into trillions of cells. These cells organize in a special way to form body tissues. Tissues are groups of cells that perform a similar function. An organ is a structure that is made up of different types of tissues that do a particular job. Body systems (also called organ systems) are formed by a group of organs that perform a related task.

2. How Body Systems Are Organized Body systems are organized by what they do- not where they are located. For example, the mouth and the small intestine are located far apart- but are both part of the digestive system. Body systems are said to be interrelated, meaning that the systems work together and are dependent on one another to keep the body functioning well.

3. Body Systems & Their Functions 1.Nervous system- Controls all other body systems; sends and receives messages; makes our five senses possible. 2.Circulatory system- Brings food and oxygen to cells; removes wastes from cells. 3.Respiratory system- Adds oxygen and removes carbon dioxide from the blood.

4. Body Systems & Their Functions (cont.) 4) Skeletal & Muscular systems- Support and move the body; protect internal organs. 5) Digestive & Excretory systems- Break down food for energy; rid the body of wastes.

5. An Example Of Body Systems Working Together Let’s say that your brain sends out a message- “run!” The message is carried through nerves to the muscles. This involves the nervous system and the muscular system. To get energy, muscles need blood that is pumped by the heart. Blood contains fuel in the form of sugar, as well as oxygen to burn the fuel. This involves the muscular, circulatory, digestive, and respiratory systems.

6. An Example Of Body Systems Working Together (cont.) The muscles burn the fuel and move, causing the bones to move. The bones support the body as it runs. This involves the muscular, skeletal, and circulatory systems. Running burns up a lot of fuel. To get more oxygen, the runner gasps for breath provided by the lungs. The heart pumps faster. This involves the respiratory and circulatory systems.