Human Body Systems

Body Organization

The smallest unit of the human body is the cell. To the right is an image of one single human red blood cell. All together, the human body has a total of more than 37 trillion cells! So if were to take all the cells in your body and lined them up, encircling them around the Earth, can you guess how many times your cells would be able to circle around the planet??

Similar cells grouped together that perform the same function create tissues, and there are 4 basic types of tissues in the human body:

  • Connective tissue: connects and supports parts of the body (bone and fat are examples)

  • Epithelial tissue: covers the surfaces of the body and lines the internal organs (skin is an example)

  • Muscle tissue: contracts and allows movement of the body (heart muscle is an example)

  • Nervous tissue: carries messages between brain and body parts (brain and spinal cord tissues are examples)

The body is further organized, with many different types of tissues grouped together to create an organ, which has a specific job. An example of an organ would be the stomach (look at the image to the left).

The human body consists of many, many organs, such as the brain, our bones, the heart, our lungs, and even our skin!

Just some of many organs found in our body...

Groups of organs that work together to perform a major function make up organ systems. The stomach, along with other organs, such as the liver, esophagus, and intestines, make up the digestive system, which is responsible for breaking down food and absorbing nutrients.

In seventh grade, we are going to explore how these organ systems work together, like a team, in order for your body to function. Our focus will first be on the connection between the circulatory, respiratory, and digestive systems and how they work together to make energy for our cells. The second focus will be on how the skeletal, muscular, and neurological systems work together to allow our body to move in specific ways, and how we can get better are certain movements, like hitting a baseball or dancing.

Human Body Videos on YouTube:

These are the best YouTube channels for middle school level videos that pertain to the human body: