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Did you know that the skin is the largest organ in the body? Our skin makes up over 16% of our overall body mass and it's the only organ you can tattoo. However, there are plenty of other organs you can depict in tattoos.

We've curated a list of some of our favorite tattoos depicting organs in the human body and they range from beautiful to bizarre. Take a look at these epic tattoos from talented tattooers around the world and let us know your favorite piece from our list in the comments section on social media.

Heart

The heart is a muscular organ whose function is to pump blood throughout the blood vessels of the circulatory system. In mammals, the heart is divided into four chambers: the upper left and right atria and the lower left and right ventricles. Our hearts are approximately the size of a closed fist, whereas an elephant's heart is roughly the size of a medium-sized dog and a microscope is needed to see the heart of a fairyfly. Our hearts beat around 115,000 times and pump about 2,000 gallons of blood each day.

Brain

The brain is an organ that serves as the center of the nervous system in all vertebrae and most invertebrate animals. It's the most complex organ in the body and the cerebellum alone contains between 55-70 billion neurons. Adult human brains weigh approximately three pounds and around 75% of our brain is made up of water. The brain triples in size within the first few years of life and a human brain doesn't become fully developed until around 25 years old.

Reproductive System

The reproductive system is a group of organs responsible for sexual reproduction. When it comes to humans our reproductive systems help to determine our sex (however, some on the intersex spectrum are born with both sex characteristics)—male or female. Males' reproductive systems are located on the outside of their bodies, whereas females are located on the inside. The respective reproductive systems produce the smallest (sperm) and largest (ovum) cells in the human body, which are 3 micrometers and 120 micrometers in size.

Lungs

The lungs are the primary organs in the respiratory system and in most mammals, a pair of lungs is found on either side of the heart. The lungs extract oxygen from the atmosphere, transfer it into the bloodstream and release carbon dioxide. Humans typically breathe 13 pints of air every single minute and we exhale approximately 17.5 milliliters of water every hour. The average adult is able to hold their breath between 30 and 60 seconds, but some people (typically underwater divers) can hold their breath for up to 20 minutes.

Miscellaneous

There are approximately 78 organs in the human body, however, only five of these organs are deemed vital for survival—the heart, brain, kidneys, liver and lungs. Medical experts typically consider the appendix to be the most useless organ. Humans have 12 major body systems— the skeletal system (bones and connective tissue), nervous system (brain, spinal cord and nerves), muscular system (muscles), respiratory system (lungs), endocrine system (hormone glands), immune system (lymph nodes, spleen), cardiovascular/circulatory system (heart, veins), urinary system (bladder, kidneys), integumentary system (skin, hair, nails), reproductive system (genitals) and digestive system (stomach, intestines, liver, pancreas).