Organ System Defined.docx

Organ System Defined An organ system is a group of anatomical structures that work together to perform a specific function or task. Although we learn about each organ system as a distinct entity, the functions of the body's organ systems overlap considerably, and your body could not function without the cooperation of all of its organ systems. In fact, the failure of even one organ system could lead to severe disability or even death. The human body is composed of 11 different organ systems. These include the following:           

Integumentary Muscular Skeletal Nervous Circulatory Lymphatic Respiratory Endocrine Urinary/excretory Reproductive Digestive

Some scientists add the immune system to this list to make a total of 12 organ systems, but most people consider the immune system to be a part of the lymphatic system. You may also find texts where the lymphatic and immune systems are both included within the circulatory system, which would give us a total of ten organ systems. Still other sources separate the immune system, the vestibular system (the organs of balance) and the neurotransmitter system (chemicals that control our moods, memory, appetite, sleep, etc.) from the other organ systems, which would spawn 13 organ systems. Regardless of how you separate the different organ systems within the human body, as you study these systems, keep in mind that an organ or structure that is included in one system may also be included in another. For example, the testes and ovaries produce hormones and are therefore part of the endocrine system; however, these same structures are also involved in reproduction and thus are included in the reproductive system.