What is the brain made of?
The brain is made of about 86 billion nerve cells called neurons, plus supporting glial cells. By weight it is about 75 percent water, and much of the rest is fat.
Neurons send electrical and chemical signals to each other through connections called synapses. A single neuron can connect with thousands of others, creating hundreds of trillions of synapses in total. Glial cells, about as numerous as neurons, support them by providing nutrients, cleaning up waste and helping signals travel faster.
The brain has two main kinds of tissue. Gray matter contains the cell bodies of neurons and is where much of the processing happens. White matter contains long nerve fibers wrapped in a fatty coating called myelin, which gives it a pale color and speeds up signals between different parts of the brain.
Hungry for energy
If you remove the water, the brain is about 60 percent fat, which makes it one of the fattiest organs in the body. Although it makes up only about 2 percent of body weight, the brain uses roughly 20 percent of the body's energy, mostly from glucose delivered by a dense network of blood vessels.
Did You Know?
The brain itself has no pain receptors, which is why surgeons can operate on it while some patients stay awake.
This answer is general information, not medical advice. For a personal health question, talk to a doctor.