1. The Human Body Systems By the Fourth Grade Computer Class
2. The human body is like a complex organization that has an important job to get done. In order to get everything done perfectly and on time, it has to use a system. Actually, the human body uses many systems that work side by side . The Human Body Systems by Bobby
28. The Respiratory System Air is breathed in through the nasal cavity and/or mouth and down through the throat (the pharynx). The air passes down the trachea (the windpipe), through the left and right bronchi, and into the lungs. Oxygen in the blood is delivered to body cells.