Some science behind the scenes

Meridians, arteries and veins

Energy flows tend to mirror the course of both the various nerves in the body and blood flow and can thus be mapped to the Physical nervous system  and the Blood Circulatory system. 

Very very roughly speaking there is also a correspondence between the ‘hot’ yang energy and the sympathetic nervous system [red below]or the Arteries and the ‘cold’ yin energy [blue below]and the parasympathetic nervous system or veins.

One might think of the nerves and blood vessels as the communication system in a computer network, whereas the energy flows are the software messages that travel over the network.  The difference is important as a ‘message’ has information content and can be directed to specific points on the body.  A nervous impulse, neurotransmitter or hormone has no information content – it is just a carrier.