Organs and systems

An organ is a structure built from two or more of the four tissue types, working together as a single unit with a defined job. The heart, for example, is mostly muscle tissue wrapped in connective tissue and lined with epithelium. The stomach combines muscle tissue (to churn food), epithelium (to line and protect its surface), connective tissue (for structure), and nervous tissue (to control its activity).

An organ system is a group of organs that cooperate on a shared, larger job. The circulatory system pairs the heart with a network of blood vessels to move materials around the whole body. The digestive system strings the stomach, intestines, liver, and other organs together into a single processing line for food. Across this course you will build and run several of these systems in the Body Lab, watching the organs cooperate in real time.