How Much Do You Know About the Human Brain?

Becky Stigall

Image: Shutterstock

About This Quiz

You know you can't live without it. And you probably know that it is the body's control center. But how much do you really comprehend about the human brain?

How much does the human brain weigh?

The human brain weighs an average of 3.3 pounds. That's about two percent of the average body weight.

What structure makes up 85 percent of the brain's weight?

The cerebrum is made up of the two cerebral hemispheres and serves as the very top of the central nervous system.

Approximately how many neurons are housed in the human brain?

86 billion nerve cells, or neurons, are housed within the gray matter of the human brain.

What makes up the white matter of the human brain?

There are literally billions of nerve fibers in the human brain. These are made up of axons that carry nerve impulses.

What is the technical term for brain nerve cell connections?

Synapses are connections, and there are trillions of them in your brain.

The human brain has how many hemispheres?

There are two hemispheres, the right and the left, connected by the corpus callosum, which is made up of a bunch of nerve fibers.

Speech and language centers are in what brain hemisphere?

The human speech and language centers are in what we often call the left brain. These areas are called Broca's area (speech) and Wernicke's area (language).

Artistic ability is thought to be housed in what side of the brain?

More creative abilities, like artistic ability, spatial reasoning and visual processing, are housed in the right hemisphere of the human brain.

What structure connects the left and the right hemispheres of the brain?

The corpus callosum is the bridge between the left and right hemispheres of the human brain. This bridge is made up of nerve fibers.

What side of the brain controls the muscles of the right side of the body?

The left hemisphere controls the muscles in the right side of the body and vice versa.

True or False? You use only the left hemisphere of your brain to do math.

Although math skills are primarily a left-brain activity, you use all of your brain all of the time.

What is an EEG?

An EEG, or Electroencephalogram, measures electrical activity in the brain. It's one non-invasive way to study sleep patterns.

What percentage of the body's resources does the brain consume?

The brain is an energy hog, consuming about 20% of the body's oxygen and energy resources.

What side of the brain controls the muscles of the left side of the body?

The right hemisphere controls the muscles in the left side of the body and vice versa.

How much of your brain is made up of water?

Your brain is about 73% water, but it takes only about a 2% water deficit (dehydration) to affect the way it functions.

True or False? You use only the right hemisphere of your brain to paint a picture.

Although artistic skills are primarily a right-brain activity, you use all of your brain all of the time. Both eyes and both arms are surely involved.

What happens to the brain when you sweat?

Work up a sweat for 90 minutes or more and your brain will shrink as much as if you have gotten a whole year older. (Yes, the brain shrinks as we age.)

How much of your brain is fat?

Your brain is made up of 60% fat, which means it is the fattiest organ in your body.

True or False? Your brain contains cholesterol.

Actually, your brain needs cholesterol, so that's not a bad thing. Without adequate cholesterol, your brain cells will start to die.

How many synapses does each brain neuron make?

Synapses are connections, and each neuron within your brain has about 40,000 of them.

How long can you go without oxygen before you will experience brain damage?

After five minutes, a lack of oxygen to the brain can cause irreparable damage.

True or False? A two-year-old's brain is the same size as an adult's.

Close, but not exactly. A two-year-old's brain is about 80% the size of an adult brain.

True or False? The brain is fully formed by puberty.

Definitely not! The human brain is not fully formed until about age 25.

True or False? Information travels through the brain at about 60 miles per hour.

Not even close. Information travels through the brain at up to nearly 270 miles per hour. However, the slowest rate of travel is as low as one mile per hour.

If your brain were a light bulb, how many watts would it generate?

Your brain generates 12-25 watts of electricity. Maybe that's why cartoons often show a light bulb above the head for good thinking or a "bright idea."

How many thoughts does the brain generate every day?

Out of those 50,000 thoughts, it is believed that as many as 70% of those thoughts are negative.

True or False? Men have bigger brains than women.

Yup. Men's brains are about 10% bigger than women's brains, even once adjusted for the larger male body size.

True or False? Albert Einstein's brain was smaller than average.

It's true! Einstein's brain weighed in at only 2.71 pounds, which is about 10% smaller than average. Not to worry, though, he had a greater than average neuron density, so he clearly made up for lost size.

True or False? Humans have the biggest brains among mammals.

Actually, the biggest brain honor goes to the sperm whale, which has a brain that weighs in at 17 pounds.

True or False? We use only about 10% of our brains.

Actually, even when we're asleep, the majority of our brain is actively processing information. Don't spread the popular 10% myth.

True or False? Alcohol kills brain cells.

Actually, alcohol damages the ability of brain cells to communicate. It doesn't kill the cell itself.

How many miles of blood vessels are in the human brain?

Oxygenated blood needs to reach every nook and cranny of the brain to keep it energized and functioning properly.

True or False? The brain starts to slow down at about 50 years of age.

Actually, the brain begins to lose steam at about age 24. However, different parts of the brain slow down at different times.

True or False? When you're drunk, your brain can't remember things.

Actually, your brain doesn't forget things when you're drunk - it can't form memories at all. That's why you don't remember what you did last night.

What is the name of the procedure during which surgeons remove half of the brain?

During a hemispherectomy, half of the brain is removed or disabled. This operation may be done to prevent seizures - in extreme cases.

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