Cells are tiny forms that make up all living things. In some, more sophisticated organs, there are many cells that work together on one common task. When cells work together in this way, they form tissue. Tissue is a group of cells cooperating to perform a specialized task. Both plants and animals contain tissue. The human body contains four types of tissue: epithelial, connective, nervous, and muscle.
Epithelial tissue is a group of cells that cover organs. It essentially serves as a barrier between the organ and the outside environment. The best example of epithelial tissue is skin.
Connective tissue holds other tissue together. Connective tissue has to be very strong and flexible in order to fulfill this important role in the human body. Bone is an example of connective tissue because it is made up of layers of cells that essentially connect with other tissue.
All nervous tissue is a part of the nervous system. This means that nervous tissue is a part of the brain and spinal cord. Nervous tissue contains neurons which are responsible for transmitting messages throughout the body.
Muscle tissue is made of muscle cells. It is attached to organs of the body and is responsible for movement.