Commonly known as meridians, their proper name is energy channels. They are 12 and are arranged in symmetrical pairs on both sides of the body. Additionally there is a number of 8 channels that have specific, more special functions.
Although their names seem to be linked to that of some organs, it might be surprising to hear of an organ called „triple heater”. It should be noted that in traditional Chinese medicine terms we use them for physical organs and also to represent certain physical functions of the body.