Re: Ki and "Connective Tissue"
Rather than asking "what is Ki?" as just saying so leads to nothing most can relate to in practice I would say it's better to give something that someone could at least relate to and then through practicing that be able to feel and understand Ki better and especially feel and understand what it isn't.
You cannot physically create Ki, you cannot mentally create Ki, it is spiritual. It takes spiritual perception to recognize it.
As it is something you can perceive a good place to start is 'the energy of goodness'.
In use it actually relates more to kindness.
It can flow through the whole body so relating it only to certain 'connective' parts is a limited view.
What is God? Just add another 'o'.
What principle is vital to the practicing of it? Non-resistance.