Organ Systems
Middle School
Definition
Groups of organs that work together to carry out a major body function, such as the digestive system or circulatory system. The body's systems cooperate to keep the whole organism alive and healthy.
Worked examples
The digestive system (mouth, esophagus, stomach, intestines, liver, pancreas) breaks down food into nutrients the body can absorb.
Multiple organs cooperate to accomplish one major function—digestion and nutrient absorption.
The circulatory system (heart, blood vessels, blood) delivers oxygen and nutrients to cells and removes waste products.
Different organs work together to transport materials throughout the body.
The respiratory system (lungs, trachea, diaphragm) and circulatory system cooperate to deliver oxygen to tissues.
Organ systems interact with each other to keep the whole organism functioning.
Common mistakes
- An organ system is just one organ doing a job → An organ system is multiple organs working together for a major function A single organ is not a system—systems require cooperation among several organs.
- Each organ system works independently without affecting others → Organ systems constantly interact and depend on each other The respiratory and circulatory systems, for example, must work together to deliver oxygen to cells.
- Tissues and organ systems are the same thing → Tissues make up organs; organs make up organ systems Organization goes: cells → tissues → organs → organ systems. Each level is more complex.
Where you'll use it next
Understanding organ systems is essential for studying human anatomy and physiology, health and disease, homeostasis, and how body systems respond to exercise, stress, and environmental changes in advanced biology.
See also
Reviewed by Pat Cheng, M.Ed. — StudyPug Curriculum Lead · Last updated June 6, 2026