THE HUMAN BODY

Our body is like a complex machine. It has lots of parts that work together. The most important parts are called organs. Organs form body systems. We are going to look at the four body systems involved in nutrition:  the digestive system, the respiratory system, the circulatory system and the excretory system.

The digestive system is a group of organs that work together to help us break down food into nutrients. 

The respiratory system is a group of organs that help us breathe. The lungs are the main organs in the respiratory system. We breathe in oxygen and we breathe out carbon dioxide.

The circulatory system moves the blood through the heart and around the body in the arteries and veins. Blood gives our body nutrients and oxygen.

The excretory system is a group of organs that work together to help us eliminate waste products from our body. The most important organs are the kidneys that filter the blood and produce urine.

The skeleton is made up of bones. The skeleton has three parts: the skull, the torso and the limbs. The skeleton has two main functions: it supports our body and it protects the internal organs. Our bones are connected at joints. Our elbows, knees, shoulders, wrists and ankles are all joints. 

There are over six hundred muscles in our body. Muscles help us move, give our body shape and also protect our internal organs. Most muscles are connected at bones. Muscles move bones by contracting and relaxing. We have two types of muscles: voluntary and involuntary.