The brain has an extremely high metabolic demand.

It weighs 2% of your body but uses 20% of oxygen and 20% of the glucose that your entire body consumes.

So, your brain is exquisitely sensitive to a lack of blood flow.

That means your body has to keep brain blood flow extremely constant under normal physiologic conditions.

While your autonomic (fight or flight vs. rest and digest) regulates blood pressure elsewhere in the body, it doesn’t regulate brain blood flow.

Instead, your body maintains adequate and consistent brain blood flow through a system called autoregulation.

Scientists are still trying to fully understand how autoregulation works, as it’s a very complex coordination between the nervous and cardiovascular systems.

Factors involved in this process include:

- Nitric oxide (NO)

- Hydrogen ion

- Potassium

- Oxygen

- Adenosine

- And neural-astrocytes.

Endothelial cells, which line the blood vessel walls, play an important role in autoregulation as well.