Then correct me - what non-respiratory chemical reactions in the human body do not require a liquid solution of some sort?
There's more to a human body than a liquid solution of some sort. That was easy.
Now it's your turn for a question. Why isn't all medical research simply done in vitro?
“...what non-respiratory chemical reactions in the human body do not require a liquid solution...?
Why exempt respiratory reactions? Oxygen transport from the lungs requires a liquid medium - blood. Btw, not all liquid media in the body are solutions - red and white cells in the blood are not “in solution”.