All vertebrates have a bloodbrain barrier that allows metabolism inside the brain to operate differently from metabolism in other parts of the body. Glial cells play a major role in brain metabolism by controlling the chemical composition of the fluid that surrounds neurons, including levels of ions and nutrients.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What type of cells have a huge role in brain metabolism?
Glial cells