Major Human Body Systems
The human body consists of approximately 11 major organ systems that work together to maintain homeostasis and support life.
The Complete List of Body Systems
Based on medical literature and clinical practice guidelines, the major systems include:
Cardiovascular (Circulatory) System - includes the heart, blood vessels, and blood; responsible for circulation and oxygen delivery 1
Respiratory System - encompasses the lungs and airways; manages gas exchange and breathing 1
Nervous System - comprises the brain, spinal cord, and peripheral nerves; controls coordination and communication 1, 2
Digestive (Gastrointestinal) System - includes organs from mouth to anus; processes food and absorbs nutrients 3
Endocrine System - consists of hormone-producing glands; regulates metabolism and growth 3
Renal (Urinary) System - encompasses kidneys and urinary tract; filters blood and maintains fluid balance 1, 3
Musculoskeletal System - includes bones, muscles, and connective tissues; provides structure and movement 4
Integumentary System - comprises skin, hair, and nails; protects the body and regulates temperature 4
Immune (Lymphatic) System - includes lymph nodes, spleen, and immune cells; defends against disease 2
Reproductive System - encompasses sex organs; enables reproduction 3
Hematologic (Coagulation) System - includes blood cells and clotting factors; maintains hemostasis 1
Clinical Context
The EASL-CLIF-C scoring system specifically identifies six major organ systems when assessing organ failure: liver, kidney, brain, coagulation, circulation, and respiration 1. The American College of Cardiology/American Heart Association guidelines similarly reference major organ systems when evaluating surgical risk, including cardiac, renal, pulmonary, central nervous system, gastrointestinal, and hepatic systems 1.
The exact number varies slightly depending on classification schemes - some sources combine systems (e.g., cardiovascular includes both heart and circulation) or separate them (e.g., distinguishing between coagulation and hematologic systems), but 10-11 systems is the standard medical framework 5, 4.