The sun, its planets, and their satellites are the largest objects in the solar system. The planets have satellites that orbit them. The moon is the earth's satellite. This chapter reviews the solar system and some ways scientists study it. The smallest units of the human body are the cells.
Cells work together as tissue, tissues work together as organs, and organs work together as systems.
Muscular, skeletal, and digestive systems are important systems in the human body. This chapter reviews these three systems. Human Body - Staying Healthy Diseases caused by germs are catching, but other diseases, such as diabetes and cancer are not catching. To help us stay healthy, we should eat a balanced diet, get plenty of exercise, and rest. We should also use drugs and medicines correctly.