You know that cells are the smallest complete living things. In plants and animals with more than one cell, groups of cells in work together. In skin, for example, different kinds of cells do different kinds of jobs. Some special cells in the skin give off small amounts of oil. The oil helps protect the skin from drying out. These and other skin cells help to protect the surface of your body.
Muscle cells are grouped together in fibers. The length of fibers can change. They can become shorter and thicker. Or they can stretch out. In this way, your bones and joints are made to move.
Bone is one of the hardest kinds of matter in your body. The hard matter in bone is made from minerals in the food you eat.
Groups of nerve cells carry message to all parts of your body. The nerve cells must work together so that the nerve tissue can do its job.
Organs are made of different kinds of tissues that work together. The tongue is the organ that you use for tasting. You also use your tongue when you talk and when you swallow food. It is made of blood, muscle, skin, and nerve tissue.
Organs and tissues work together to carry out jobs such as breathing or removing wastes from the body. What is the name given to groups of organs and tissues that work together as a team? They are called system. You are going to find out more about some of your body system.