 System- group of parts that work together  Systems work together to form a larger unit. (Example: Organ systems work together to form our bodies.)  The cooperation between these systems allow our bodies to function.

 Our bodies need energy and materials for growth.  This energy comes from the foods we eat.  Our digestive system breaks down food so it can be used by the body.  Our digestive system includes our mouth, liver, pancreas, small intestine, large intestine, esophagus, and stomach.

 The digestive process begins when we chew. Chewing breaks our food into smaller pieces.  The food then travels to the stomach where it is mixed with chemicals that help break it down further.  The food then passes to the small intestine where more chemicals continue to break the food down.  The chemicals that assist in breaking our food down are made by the liver and pancreas.  At this point, while food is in the small intestine, nutrients are absorbed by our body.  In the large intestine, water is absorbed from food and taken into the body  Food that has not been digested becomes waste

 Carries blood, oxygen, food, and wastes throughout the body  This system includes the heart, blood vessels, and blood  The heart is the main organ in this system  The circulatory system works with other systems (Example: Respiratory system takes in oxygen from air in the lungs, and the circulatory system carries the oxygen to all of the cells in your body.)

 Heart pumps blood through blood vessels called arteries  Blood moves through the arteries into capillaries  In the capillaries, oxygen and food move from the blood to cells  Carbon dioxide moves from cells to blood  Blood then moves through the veins, which carry it back to the heart

 Takes in oxygen from the air we breathe  Lungs are main structures of the respiratory system

 When you breathe in, air moves down your throat and into your lungs  Oxygen is taken in through the lining of the lungs  Carbon dioxide is removed from your body (The air you breathe out has less oxygen but more carbon dioxide than air you breathed in.)  The diaphragm, which lies below your lungs, and muscles attached to your ribs make your lungs breathe in and out. (These muscles are NOT part of the respiratory system.)

 The skeleton is the basic framework of the body.  The skeletal system consists of 206 bones that give the body structure, support, and protection. (Example: The skull protects the brain, and the ribs protect the heart and lungs.)  Bones could not work without muscles to pull on them and make them move.  The muscular system is made up of all the body’s muscles.

 The nervous system controls all the other systems in the body.  The brain, which collects information and makes decisions, is the core of the nervous system.  The brain is connected to all parts of the body by nerves. The nerves carry instructions from your brain to the rest of your body.  The nerves also carry information from the body to the brain through sensory organs.