Organ Systems

The most complex organisms have organ systems. An organ system is a group of organs that act together to carry out complex, interrelated functions, with each organ focusing on a subset of the task. For example, the human digestive system is an organ system in which the mouth and esophagus ingest food, the stomach crushes and liquefies it, the pancreas and gall bladder make and release digestive enzymes, and the intestines absorb nutrients into the blood. An organ can be part of more than one organ system. For example, the ovaries produce hormones, which makes them a part of the endocrine system; the ovaries also make eggs, which makes them a part of the reproductive system as well. One of the most important functions of organ systems is to provide cells with oxygen and nutrients and to remove toxic waste products such as carbon dioxide. A number of organ systems, including the cardiovascular and respiratory systems, work together to do this.