Organ and Organ Systems
The Human Organ System
The smooth functioning of organ systems enables an organism to carry out its essential processes.
The human body is made up of 12 organ systems: circulatory, digestive, endocrine, excretory/urinary, immune, integumentary, lymphatic, muscular, nervous, reproductive, respiratory, and skeletal.
The following tables provide information on the functions of a human organ system along with the major organs involved.
| Organ System | Functions | Major Organs |
|---|---|---|
| Circulatory | Transports oxygen and nutrients to all cells of the body; removes carbon dioxide and other waste products | heart, blood, blood vessels |
| Digestive | Breaks down and turns food into nutrients that the body can easily absorb and use to make energy | mouth, esophagus, stomach, small intestine, large intestine |
| Endocrine | Secretes hormones that regulate the body's functions related to growth, sexual development, mood, tissue function, and metabolism | pituitary gland, adrenal gland, thyroid gland, reproductive gland, pancreas, parathyroid, pineal gland, thymus gland, hypothalamus |
| Excretory/Urinary | Gets rid of the body's wastes such as excess or harmful liquids and gases. | lungs, liver, skin, kidneys, ureters, urinary bladder |
| Immune | Protects the body against disesase-causing microgranisms, such as viruses, bacteria, parasites, and tumor cells; locates, identifies, and destroys these microorganisms | thymus, spleen, lymph nodes, antibodies, mucus |
| Integumentary | Covers and protects the internal tissues and organs from damage; helps maintain homeostasis or internal balance as it regulates body temperature and water balance; protects the body from harmful organisms; releases excess heat and wastes | skin, nails, hair, sweat glands |
| Lymphatic | Returns fluid from body tissues to the blood; defends the body against diseases and infection as it filters out foreign bodies such as viruses, bacteria, toxins, and cancer cells; generates antibodies; absorbs fats and fat-soluble vitamins and transports them to the blood | lymph nodes, lymph vessels, thymus, spleen |
