Do You Know These Amazing Facts About the Human Body?


By: John Miller

5 Min Quiz

Image: YouTube

About This Quiz

Did you know that humans have about the same number of body hairs as chimpanzees? Don't rush off to find a razor. Instead, take our fascinating quiz about the wild and weird nature of the human body!

True or false: Does the human body emit a tiny bit of visible light?

We are an illuminated species -- the human body literally glows, casting of a bit of visible light in the darkness. But it's such a small amount of light that we can't detect it with our naked eyes.


Which human organ can regenerate itself if parts of it are removed or damaged?

The liver is one of your body's most durable organs. Not only does it help clean toxins from your body, but it can regrow itself if it is damaged.


The human brain is made up mostly of _____.

The human brain weighs about 3 pounds, and most of that weight comes from fat. Delicious, yummy fat that zombies eat like butter.


Babies can't shed tears until they are what age?

Newborns don't have fully developed tear ducts, so they don't shed tears until they are 1 to 3 months old. But as any parent can tell you, that doesn't stop babies from screaming their heads off.


How much saliva does your mouth produce each day?

Each day, you need a lot of saliva to keep your mouth moist and to help you eat. Your body produces roughly 1 quart per day, but please don't start spitting in a jar to prove it.


The length of your arms stretched out is roughly equal to _____.

Your wingspan is roughly the same as your height. This is yet another reason that 7-foot-tall men make such good basketball players.


True or false: Can the human brain itself feel pain?

The human brain is the centerpiece of the nervous system, but the brain itself cannot feel pain. If you get migraines, you might disagree.


About how long can your brain survive without oxygen before incurring damage?

If your heart stops beating, rescuers generally have about 5 minutes to revive you before brain damage sets in. However, in extremely cold conditions, body processes slow … and the brain can survive much longer without oxygen.


If you laid an adult's blood vessels end to end, how far would they stretch?

The equator is about 25,000 miles long, and your adult blood vessels could circle the equator about four times, meaning your circulatory system is roughly 100,000 miles in total length.


Your stomach acid can dissolve _____.

Stomach acid has a pH level of between 1.0 and 2.0, a fact that helps keep your gut from being invaded by foreign microbes. The acid is strong enough that, given the right conditions, it can dissolve steel. Please don't eat a fork to test this theory.


Why is your left lung a little smaller than the right lung?

Humans naturally have a left lung that is smaller than the right. That's because you need room for your ribcage and heart.


The wrinkles in the human brain are associated with ______.

The human brain is one of the most wrinkled and folded in the animal kingdom, and its complexity is associated with intelligence. Less intelligent animals like mice and politicians have much smoother brain matter.


True or false: Is it possible to sneeze with your eyes open?

Nerves link the nose and eyes, so when you sneeze, the tendency is to shut your eyes tight. But some weirdos are able to sneeze with their eyes wide open, freaking out innocent bystanders and small children.


How many times does the average human heart beat per day?

On average, the human heart beats just under 5,000 times per hour, or 115,000 times per day. Unless, of course, we're talking about my cold-hearted mother-in-law. Hers doesn't beat at all.


True or false: Is the appendix totally useless to the human body?

The appendix is notorious for sudden (and life-threatening) infections. But this little organ is beneficial to the bacteria that make your digestive system work properly.


How do the retinas in your eye capture the visible world around you?

Your retinas see the world upside down. But in a nifty (and necessary) trick, your brain turns the image right side up so that you don't get very, very confused.


How fast do signals travel along the nerves in your body?

Nerve impulses are incredibly fast, helping us to react very quickly to external stimuli. These impulses travel at around 275 MPH.


True or false: The vision of newborns is entirely blurry.

It's a common misconception that new babies have totally blurry vision. The reality is that most of them can see clearly to a distance of about 1 foot.


What causes body odor?

Many people mistakenly believe that sweat smells terrible. But it's actually the bacteria feeding on your sweat that generates an off-putting smell.


How many gallons of blood are in the average adult human?

You might feel like you have 1 million gallons of blood after that nasty paper cut spews all over the place. But the average adult is only slogging around with maybe 1.5 gallons of the vital fluid.


Compared to other vertebrates, the human _____ is the largest organ in relation to body size.

Humans have big brains with regard to their body size. Their big brains are why they rule the animal kingdom.


What is the largest human body cell?

The ovum (egg) is the largest human body cell. Compared to many cells, the egg is huge -- it has a diameter of nearly 1 millimeter.


How many times does the average person blink per minute?

Most people blink approximately 17 times per minute. Unless, of course, you're a shady politician and you're lying at the podium. Then you might blink so much that people offer you eyedrops.


True or false: Is there any truth to the common perception that women become cold easier than men?

Women have more body fat near their body cores, but their extremities aren't as protected. Plus, when exposed to cold temperatures, the blood vessels in their hands constrict more quickly than men's.


Each hour, your eyes produce what volume of teardrops?

Your eyes require significant lubrication. That's why your tear ducts produce about 1 teaspoon of fluid every hour.


Your blood accounts for how much of your body weight?

Humans have roughly 1.5 gallons of blood. That means blood accounts for 8% of your total body weight.


How many times might your heart beat over the course of your lifetime?

The human heart is incredibly powerful … and strong. It may pump more than 3 billion times during an average human life.


Which part of the human body produces red blood cells?

Bone marrow is incredibly important to human life -- it produces the blood cells that keep us alive. Each second, marrow manufactures about 2 million new blood cells.


True or false: Are achy bones a sign that bad weather is coming?

Maybe you've witnessed your grandparents rubbing their aching bodies and swearing that a storm is coming. Scientists aren't sure, but people who have inflammation or arthritis may indeed feel shifts in barometric pressure, which can indicate that a change in the weather is imminent.


How many neurons (nerve cells) are there in the brain?

Granted, no one's ever going to sit there with a microscope and count them all by hand. But scientists estimate that there are 100 million neurons in the human brain.


Explore More Quizzes

About HowStuffWorks Play

How much do you know about dinosaurs? What is an octane rating? And how do you use a proper noun? Lucky for you, HowStuffWorks Play is here to help. Our award-winning website offers reliable, easy-to-understand explanations about how the world works. From fun quizzes that bring joy to your day, to compelling photography and fascinating lists, HowStuffWorks Play offers something for everyone. Sometimes we explain how stuff works, other times, we ask you, but we’re always exploring in the name of fun! Because learning is fun, so stick with us!