10 Quick Facts About the Brain

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There are still many mysteries about the human brain, but researchers have uncovered a number of interesting facts about how the brain works. Here are ten quick facts to get you started on the path to a better understanding of the brain.

1. The Brain Is Heavier Than You Might Think

The average adult human brain weights approximately 3 pounds.

2. The Brain Is Mostly Water

The human brain is composed of approximately 75 percent water.

3. The Brain Grows Tremendously From Infancy to Adulthood

The average weight of a newborn human infant brain is about 350 to 400 grams.

4. The Brain Is Made Up of Billions of Neurons

Recent estimates suggest that the average adult brain contains approximately 86 billion neurons.

5. But the Bulk of the Brain Is Made Up Of Non-Neuron Cells

Only about 10 percent of the brain is made up of neurons; the other 90 percent is mostly composed of glial cells. Glial cells perform a range of functions, including acting as a "glue" to hold neurons together. They also perform housekeeping functions by cleaning up excess neurotransmitters and supporting synaptic growth.

Glial cells support neurons by providing support and nutrition. There are several different types of glial cells: astrocytes, oligodendrocytes, microglia, ependymal cells, radial glial, satellite cells, and schwann cells. It is estimated that there are 10 to 50 times more glial cells than there are neurons in the brain.

6. The Brain Can Form New Cells, Even In Adulthood

The brain continues to form new connections between neurons throughout life. Old beliefs suggested that the brain was fairly set in stone early in life, but neuroscientists now know that the brain never stops changing.

7. Traumatic Brain Injuries Are Prevelent

Among children and adults between the ages of 1 and 44, traumatic brain injury is the leading cause of disability and death.

8. Falls and Car Accidents Are Two of the Most Common Causes of Brain Injury

The most common causes of traumatic brain injury include falls, motor vehicles crashes, and assaults.

9. Brains Have Actually Been Getting SmallerĀ 

The average size of the human brain has decreased by about 9 cubic inches over the past 5,000 years.

10. The Human Brain Requires a Lot of Energy to Function

While it represents only about 2 percent of the body's total weight, it requires about 20 percent of the body's oxygen and 25 percent of the body's glucose.

Learn more about the brain:


Brain Trauma Foundation. (n.d.). TBI statistics: Facts about TBI in the USA.

Pappas, S. (2011, February 18). 10 things you didn't know about the brain. Live Science.

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