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How many organs are in the human body?

Asked by: Zach Madison
School: Maine-Endwell Middle School
Grade: 6
Teacher: Kevin Wagstaff
Hobbies/Interests: Sports, reading, hiking and video games
Career Interest: Law enforcement

Answer from Erik Hiester

Visiting Professor, Binghamton University

Research area: Biomedical Engineering

This an excellent question, and there is no clear answer. Before this question can be answered, one must first have a definition of what an organ is. 

To begin, lets start with the cell. There are many different cells in the body. In fact, there are about 100 trillion cells. These cells don’t function well on there own but are part of the larger organism that is  - you. Cells group together in the body to form tissues, a collection of similar cells that group together to perform a specialized function. 

The next level of organization of the body is an organ. The standard definition is a collection of at least two tissues that function together for a common purpose. Examples of organs are skin, liver, heart and lungs. Now, just as an organ is a collection of tissues that work together, an organ system can be defined as a collection of organs that work together to perform a function, such as the circulatory system, digestive system, or nervous system. In the literature there are varying reports of the number of organs and organ systems, all of which are dependent on the definition. For example, if each bone and muscle were considered a separate organ, then the number of organs would exceed 1,000.  Likewise, for the digestive system, the small intestine might be considered one organ, or, perhaps, three organs; the duodenum, the jejunum, and the ileum.

In summary, there is no definitive answer to this question. The human body is complex, and our attempts at categorization are often not as straightforward as one might think!  

Last Updated: 9/18/13