© iStock

Microorganisms - We have trillions of microorganisms in our bodies, but a study found that more than 99% are unknown to science.

© Shutterstock

We breath out excess weight - When we lose weight, fat cells turn into carbon dioxide and are then expelled through our lungs.

© Shutterstock

A fetus will cure mom's heart - If a pregnant woman has damaged heart tissue, the fetus will donate stem cells to heal it.

© Shutterstock

Male soldiers with breasts - Germany's Wachbataillon military guards are growing breast tissue on the left side of their chests. Doctors say this is because of the drill they do, where they hit that area repeatedly with their rifles.

© Shutterstock

Redheads - Redheads experience pain differently from other people. They actually need around 20% more anesthesia to feel no pain.

© iStock

Gut feeling -

Your brain and your gut are actually connected. It's called the gut-brain axis.

© iStock

Gamers make good surgeons - A study shows that surgeons who played video games regularly had better laparoscopic surgical skills.

© Shutterstock

Cholesterol and violence - A study shows that there is a link between individuals with low cholesterol levels and violent crime.

© Shutterstock

Poop transplant - Fecal transplantation, also known as bacteriotherapy, is when healthy fecal bacteria is transplanted to a person requiring treatment. It can be done through a colonoscopy or through pills.

© iStock

Heart and music - Music tempo and volume has a direct impact on heart rate. This means that fast music played at high volume will increase your heartbeat, and the opposite is also true.

© Shutterstock

Gas - If you don't fart, some gas may re-enter your blood stream and it will be released through your breath.

© Shutterstock

Sense of smell - You lose your sense of smell when you're asleep.

© Shutterstock

Contralateral lung transplantation - When a lung transplant is required but the organ available is from the opposite side, surgeons flip it and attach it (i.e. left lung on the right side).

© Shutterstock

Fingernail and toenail regrow rate - If you lose a fingernail, it will take six months to regrow, but in the case of a toenail, it can take up to a year and a half!

© Shutterstock

Sweaty feet -

A pair of feet has approximately 250,000 sweat glands. This is where most of your sweat glands are located.

© Shutterstock 

Bagel-related injuries - In 2008 almost 2,000 people in the US went to the hospital with bagel-related injuries.

© Shutterstock

We share 90% of our DNA with cats - We are genetically closer to cats than we are to dogs.

© Shutterstock

Retained surgical items - In the US alone, every year about 2000–4000 objects are left inside patients' bodies after surgeries.

© Shutterstock

Extra bones - Adults have 206 bones. But we are actually born with 300 bones! Most of these are in fact cartilage that will then fuse and turn into bones.

© Shutterstock

Tongue is the new fingerprint - Everyone has unique fingerprints, but the tongue also has a unique print.

© Shutterstock

Alcohol prescribed by doctors - Alcohol is sometimes prescribed to alcoholics before surgical procedures to avoid withdrawal symptoms.

© Shutterstock

Three kidneys -

When performing kidney transplants, many times the diseased organ is not removed. Instead, a third kidney is added.

© Shutterstock 

Cornea -

The cornea has no blood vessels, so it needs to get oxygen directly from air.

© Shutterstock 

My baby's poop is better than yours - Mothers prefer the smell of their own babies' poop, and don't find the smell as bad as other children's feces.

© Shutterstock

Your liver has a superpower - Livers have the ability to regenerate. This mean they will regrow if parts are removed.

© iStock

Women have "younger" brains - A study found that women's metabolic brain age is about four years younger than men's.

© iStock

Oops, that's the wrong leg! - Wrong-site surgery in orthopedics is more common than you might think.

© Shutterstock

Medical malpractice -

According to a 2017 report, 55% of physicians in the US have been sued for malpractice.

See also: What are the worst pains that humans can suffer?

© Shutterstock