I don't know why everyone insists on hand-waving away every point I bring up about why it would be impossible for the chakra system to be physical but ok...
Probably because you have done the same with other people's assumptions.
Every mall around here has at least one, I don't know, Ohio is weird. But the point is that image is just so you understand how the acupuncture, theoretically, works. It is not saying the inside of your foot actually looks like that.
The theoretical aspect of acupuncture still impacts physical systems, theoretically at/via the regions shown, which are physical in nature (they may not look like that nor be shaped like that, but said regions do exist. The wrong placement can screw the whole thing up).
... With that being said, I posit that chakra is a fundamental force of the Naruto universe that, as shown in the show, doesn't normally interact with the electromagnetic force unless in extremely large or concentrated doses (hence it being invisible to the naked eye in most cases and only becoming visible when a person has a crap ton of chakra or when it's concentrated)...
And with special dojutsu it is also visible. However, the chakra circulatory network cannot itself be made of chakra, because by your argument, chakra is a fundamental force, and though a fundamental force can transfer energy, it is not itself matter. If the matter making up the network and permitting the circulation is made of something other than chakra, it has to be able to interact with the body at least for the acquiition of physical energy and at most in order to aide with life processes.
Remember, when chakra equals absolute 0, said person dies according to Kakashi, so even a 1 bit of chakra can sustain life, even if barely, meaning that the occasions where it does interfere with the EM force are not as exceptional as I originally read you intending. If an ordinary shinobi has thier arm cut off with a regular katana, they cannot channel chakra through their arm anymore the connection of regular bodily systems and of the chakra network has been cut off. Even Kakuzu had his arm still attached by special chakra threads when he detached it.
If a person's body is thrown into a pit of lava and they "melt", their chakra network is not just left behind; the network itself melts along with them. As to what happens with the chakra, we can assume that it dissipates, or perhaps even becomes natural energy. Not really sure on that one.
LIke the metal coils of an electromagnet, the physical chakra network is necessary for the proper flow and manipulation of chakra through the body. However, like magnetism, the chakra can be transferred to special objects (such as Asuma's chakra blades) to create special effects and chakra flow techniques.
To wrap what I"m saying more compactly, the chakra network cannot both be "non-physical", "intangible", "spiritual", etc. and be made of matter, "disruptable by non-chakra based attacks", etc.