What does brain needs (for example oxygen amount, vital nutrients. ...)?

All nutrients.: Your brain cells need whatever your other cells in your body need, only more often. One nutrient needed most is glucose, which is vital to correct brain function. That's why hypoglycemia is so very dangerous to the brain, as a drop in glucose can mean death of brain cells. Oxygen is also very important, and a lack of oxygen to the brain can cause massive brain cell death or a stroke.