What’s the source of energy that powers the human brain?

Mainly sugar, glucose. Glucose is decomposed and used to generate a gradient of hydrogen ions in the process (oxygen is also necessary for this, which is why we breathe). So you will get a dam with a lot of hydrogen on one side and a few hydro on the other side. Certain structures can only be used to create ATP. Subsequently, ATP is used to enhance many biological processes, including an active process to maintain the firing of neurons. (Why do you look at Fabian van den Berg's answer, why do you inhale oxygen and spit out carbon dioxide?

Neurons shoot using similar gradient methods. When the input signal is sufficient to increase the voltage, the voltage gate channel spring opens allowing sodium to flow, making it more positive. Adjacent doors also bounces, the same happens and continues to be released to the neurotransmitter synapse to do the same for the next neuron (see Fabian van den Berg for how to open the sodium channel Please give me). Polarized response neurons? For better explanation)

An active process requiring energy moves ions through the membrane to keep the neurons negative and to restore them after launch, and the energy comes from ATP.

So in the end your brain runs over sugar and oxygen. And it is used to run mitochondrial ATP machines.

The brain consumes 20% of the energy used by the body than any other organ. In humans, blood glucose is the main source of energy for most cells and important for the proper functioning of many organizations, including the brain. In people who tend to sit on an empty stomach, the human brain consumes about 60% of the blood sugar. Brain metabolism usually relies on blood sugar as an energy source, but in low glucose (fasting, endurance exercise, carbohydrate intake restriction, etc.), the brain uses ketone bodies as fuel and the necessity of glucose is low is. The brain can also use lactic acid while exercising. The brain stores glucose in the form of glycogen, but its amount is much less than liver and skeletal muscle. Long chain fatty acids can not cross the blood brain barrier, but the liver can break down them and produce ketone bodies.

Shirley: Usually, the brain uses glucose mainly as an energy source. Under conditions of low glucose such as fasting or ketone body diet, the liver produces a ketone body of acetyl CoA by oxidation of fatty acids. These ketone bodies can cross the blood brain barrier, after which neurons use them as fuel. First of all, they are very energy efficient. BHB is the major ketone that provides more energy (or ATP molecule, which is the energy currency of the cell) per unit of oxygen used in our cell biochemical reaction. Ketones also stimulate hippocampal neurons to produce mitochondria with high energy productivity