the circulatory system
The main organ of the circulatory system is the heart.
the heart is an organ while it is a part of the circulatory system
The heart is an organ.
the heart is part of the circulatory system in the body.
Its an organ
The Heart is the main organ of a circulatory system.
the heart is its own organ if you mean system it is part of the cardiovascular system.
It is an organ. The heart belongs to cardio-vasculary organ system.
The heart is the first organ to develop in a fetus. Together, blood and the circulatory system, that is powered by the heart, form the first organ system.
The circulatory system and the cardiovascular system. :D NOT jk
The heart itself is an organ. It is part of the circulatory system, though.
the heart is the centre of the organ system....... i think