12 facts about the secret life of the human body that you didn't even know (13 photos)

It seems we know everything about our own bodies. Except, perhaps, for the brain. Otherwise, all reactions, functions, and features have long been known.





But this is not true. The human body is a kind of universe. The study of which, as Reddit users have discovered, continually reveals new and quite surprising facets.

1. Invisible Tattoo Helpers



Tattoo ink is held in place by an army of living immune cells called macrophages, which don't know what to do with it. When they age and die, new cells take their place to retain the pigment.

2. Voices in the Head and More





People with schizophrenia often hear voices that whisper nasty things to them.

What happens to people who are born deaf but later develop schizophrenia?

It turns out that if they were taught sign language, their "voices" manifest as visions of hands making gestures.

People born blind do not develop schizophrenia.

People with schizophrenia from different countries also hear different voices. In India and Africa, they are much friendlier than the harsh and aggressive voices heard by schizophrenics in the United States.

3. Not a replacement, but a supplement



In most cases, barely functioning kidneys are not removed, as removal increases the rate of surgical complications. Instead, a third, donor kidney is simply added. This kidney takes on the primary function of filtering the blood.

4. The Upside-Down World



If you wear special glasses that turn the world upside down, after a few days of wearing them, your brain will correct your vision, and you'll see normally again. At that point, if you take the glasses off, your normal vision will be upside down, and it will take several hours to restore.

5. The Dangers of Sleep Deprivation



Without sleep, the brain can actually begin to "eat" itself. Microglia, the cells responsible for clearing waste in the brain, begin to destroy and engulf healthy neurons and connections, not just damaged ones. This process, known as astrocytic phagocytosis, is enhanced by sleep deprivation. Over time, this can lead to memory problems, slower thinking, and an increased risk of diseases like Alzheimer's.

6. Misleading Pain



The nerves to the teeth run quite close to the sinuses. If a person experiences an infection, sinusitis, or swelling, these nerves can be pressed, causing the brain to mistakenly believe they are a toothache.

7. Constant Renewal of the Mucous Membrane



The stomach receives a completely new mucous membrane every 3-4 days. Gastric juices would corrode metal, so the stomach requires this constant remodeling to prevent itself from dissolving. Most people don't even realize this happens every week.

8. A Unique Muscle



The tongue is the only muscle in the body that can move and bend in absolutely all directions and is attached at only one end.

9. A Smell That Isn't There



The nose can smell the lungs when you breathe, but the brain deliberately ignores this smell. Just like the brain prevents us from seeing our own nose.

10. The Special Bone



There is only one bone in our body that is not connected to any other bones. It is called the hyoid bone and is located in the throat.

11. The Willful Overlord



The brain often behaves like a selfish tyrant. When the brain feels the need to protect itself, it can and will compromise almost every other system in the body to save itself.

For example, fainting is essentially the brain's cool way of saying, "I want better blood flow, but I'm not getting it, so I'll force my body into a horizontal position."

When you lie on the floor, gravity favors better blood flow to the brain than in an upright position (the heart and brain are at the same level).

12. Modern Consequences of Evolutionary Struggle



Our body loves fat but hates muscle because fat is an energy storehouse, while muscle is useless weight. This is why building muscle is so difficult.