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The heart is the key organ in the circulatory system. As a hollow, muscular pump, its main function is to propel blood throughout the body. It usually beats from 60 to 100 times per minute, but can go much faster when necessary.
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The circulatory system is more complex than the heart because the circulatory system is an ORGAN SYSTEM.
An organ system is a group of organs that work together to perform a specific function.
For example, the circulatory system is an organ system that works together to carry oxygen and nutrients to all body tissues.
This system (circulatory system) also serves to remove carbon dioxide (CO2) and other waste products.
The circulatory system consists of the heart, blood, and blood vessels (arteries, veins, capillaries).
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