The human body is like a vast, sophisticated machine made up of smaller interlocking mini-machines, each with specific functions. Everything in the body works in close coordination with everything else. 

However, each piece or organ has unique facts and stories. Here are some of the best you can teach even your children: 

Facts about the Brain and Your Sense Organs

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• Your brain is still forming until you reach the age of 25. 
• With 86 billion neurons forming almost 1000 trillion different connections, the human brain has an unlimited storage capacity. 
• The average speed by which information travels to the brain is estimated to be around 268 miles per hour. 
• Because neurons have a high-fat content, more than 60% of the brain consists of fat. 
• Human eyes, on average, blink 20 times a minute. 
• Ears never stop growing. 
• There are around 8000 taste buds on the tongue. 
• The brain uses more energy than the rest of the body organs because it is always working even when you’re asleep.

Facts about Bones and the Skeletal System

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• Despite the hands and wrists looking smaller in proportion to the body, they are made up of many bones—54 to be exact. 
• It takes around seven years for your whole skeleton to be replaced entirely by a new one. This is because bones are living tissues that grow and replace old worn, out portions.
• Although they are bigger than your hands, feet are only made up of 26 bones on each side. 
• The main difference between soft cartilage and hard bone is the amount of Calcium they have. While hard bones have a huge amount of Calcium, cartilages have none.
• Bones stop growing longer when you reach puberty. 
• The longest and strongest bone in the human body is the leg bone or femur. 
• The smallest bone in the body is located in the inner ear. 
• Because they are living tissues, bones have the ability to heal themselves. Putting a cast on a fractured bone just ensures that the bones are perfectly aligned and not subjected to pressure when mending. 

Facts about the Respiratory System

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• Because of constant exposure to the environment (through the mouth or nasal opening), your lungs never get germ-free. 
• The lungs have folds to maximize surface area. If you unfold all these, your lungs will cover an entire tennis court. 
• Human lungs float on water.
• Sneezing is part of the body’s mechanism to expel foreign materials that get inside your nose. 
• The nose doesn’t just filter incoming air. It also warms and moistens it before it reaches the lungs. 
• You can not swallow and breathe in at the same time. 
• You can live on just one lung, although this limits your physical abilities greatly. 
• You can get dehydrated from breathing. 

Facts about the Digestive System

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• Stomach acid, also known as gastric acid, is strong enough to corrode an iron nail.
• Six glands in the mouth squirt out saliva.
• The esophagus moves food into the stomach through strong muscular contractions that look like waves. This is called peristalsis and is strong enough to allow you to eat upside down.
• While most digestive organs contain two layers of muscles, the stomach has three making it strong enough to mash food inside. 
• The lining of the stomach is constantly replaced. Otherwise, gastric acid will corrode through the layers of the stomach. 
• The small intestine is longer than the large intestine. 
• Digestion begins in the mouth. 
• Acid reflux is when gastric juice moves out of the stomach and back up into the esophagus. Although this is common, it shouldn’t be taken lightly. Since only the stomach is adequately equipped to withstand the acid, the acid in the esophagus might lead to severe damage. 

Facts about the Reproductive System

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• The largest human cell is the egg cell, while the smallest is the sperm cell.
• Women are born with a definite number of eggs. They don’t make new eggs. They just release them one at a time during ovulation.
• Men produce sperm every day. 
• The uterus stretches from the size of a closed fist to the size of a watermelon in 9 months. After the baby is born, the uterus must return to its original size in only hours. 
• After the egg cell is released during ovulation, it only lives for one to two days. Technically, she can only get pregnant for 1 to 2 days per month. 
• Males and females have both testosterone and estrogen. 
• The oldest woman ever to give birth delivered her baby at 66 years of age. 
• It’s not only women who experience menopause. Men do too. 

Facts about the Muscular System

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• The largest muscle in the human body is called the Gluteus Maximus. 
• There are more than 600 muscles in the human body
• Muscles account for roughly 40% of our weight. 
• The heart is the heart’s most complex working muscle, pumping 2500 gallons of blood daily without rest. 
• Muscle contraction generates heat. This heat accounts for 85% of the body’s heat.
• Muscles generally work in pairs. While one contracts, the other relaxes. 
• Muscles can only pull, never push. 
• The strongest muscle in the body is the masseter (jaw muscles). 

With so many interesting smaller pieces, the human body proves to be such a marvelous creation. You can’t help but admire how it works and be thankful for being alive. 

Frequently Asked Questions on the Human Body

What is the largest organ in the body?

The skin is the largest organ in the body. It covers the whole body from head to foot, separating it from the environment, sensing stimuli, and responding appropriately to keep you alive and healthy. 

What is the most important organ in the body?

All the organs in the body are vital because if any of them were to stop functioning, a person would most likely be compromised or end up dying. However, of all the many organs in the body, the one with the most influence on other organs would be the brain. This is why most people consider it the most critical organ in the body.

What is the most useless part of the body?

The most useless part of the body is a vestigial structure called the appendix. Scientists believe that the structure once played a role in ancient men’s lives when they mostly fed on plants. 

The appendix is suspected of having housed bacteria that helped early humans break down plant cellulose. However, since humans eventually evolved to have a diverse diet, the appendix was no longer needed. It is now just a reminder of evolution.