An organ system is a group of organs working together to perform a vital body function. There are twelve major organ systems in the human body.
| Organ System |
Components |
Functions |
| Cardiovascular and circulatory |
Heart, blood, and blood vessels |
Transports blood throughout the body, supplying nutrients and carrying oxygen to the lungs and wastes to kidneys |
| Digestive |
Mouth, esophagus, stomach, intestines, liver, and pancreas |
Ingests food and breaks it down into smaller chemical units |
| Endocrine |
Pituitary, adrenal, thyroid, and other ductless glands |
Coordinates and regulates the activities of the body |
| Excretory |
Kidneys, bladder, and urethra |
Removes wastes from the bloodstream |
| Immune |
Lymphocytes, macrophages, and antibodies |
Removes foreign substances |
| Integumentary |
Skin, hair, nails, and sweat glands |
Protects the body |
| Lymphatic |
Lymph nodes, lymphatic capillaries, lymphatic vessels, spleen, and thymus |
Captures fluid and returns it to the cardiovascular system |
| Muscular |
Skeletal muscle, cardiac muscle, and smooth muscle |
Allows body movements |
| Nervous |
Nerves, sense organs, brain, and spinal cord |
Receives external stimuli, processes information, and directs activities |
| Reproductive |
Testes, ovaries, and related organs |
Carries out reproduction |
| Respiratory |
Lungs, trachea, and other air passageways |
Exchanges gases—captures oxygen (O2) and disposes of carbon dioxide (CO2) |
| Skeletal |
Bones, cartilage, and ligaments |
Protects the body and provides support for locomotion and movement |
