1Human Small Intestine
The inside of the human small intestine has the same surface area as a tennis court.
2. The human stomach has more nerve endings than the spinal cord, giving a bit more meaning to gut feeling.
3. Humans can regenerate some of their organs through a process called "Compensatory Hypertrophy." When part of the liver is removed or destroyed, the remaining portion grows to the original size and allows the liver to function as it did before. Kidneys and lungs can also similarly compensate.
4. People without a functioning larynx can still speak without a mechanical voice box by using their esophagus to speak. ‘Esophageal speech,’ uses the esophagus to move air to produce vocalizations in individuals who have had their larynx (including vocal cords) removed. The skill requires a lot of practice but is a godsend to those who otherwise would not have a voice.
5. There is a protein made by placenta cells called syncytin which aids in the attachment of the placenta to the uterine wall, making it essential for nutrients to get to the developing fetus. The gene that codes for the protein actually came from a virus millions of years ago.
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6Post Workout Soreness
Post-workout muscles aren't sore because of lactic acid buildup. It’s a myth perpetuated by a doctor who experimented on a severed frog. Lactic acid is actually a fuel made from glucose and burned by the muscles to maintain energy. Soreness which is typically experienced post workout is from micro tears in the muscle and the resulting inflammation.
7. A person with damage to the right brain hemisphere can develop a "joke addiction," a compulsive need to constantly make jokes.
8. About 8-16% of humans are missing the palmaris longus muscle, which was once used for climbing.
9. Tight Pants Syndrome is a real health risk which can result in abdominal and chest pain and could also lead to “testicular torsion” in men. Testicular Torsion refers to the twisting of the testicle within the scrotum, which can lead to blood loss and if not treated within 6 hours, can result in loss of the testicle.
10. If kidney cells didn't have aquaporins, which allow cells to reclaim water from urine, humans would have to excrete about 180 liters of urine per day.
11Low Frequencies & Human Ears
Human ear can't tell where low frequencies come from. This is why subwoofers can be hidden in home theaters or in trunks of cars.
12. Retinal is a photoreactor molecule present in the human eyes, but it has to leave the eye and be recycled through the liver once it has been exposed to light.
13. There is a valve in fetal heart that diverts blood away from the lungs while in utero. It begins closing as the baby takes its first breath after being born and gets oxygen from its own lungs for the first time.
14. Agenesis refers to the failure of an organ to develop during embryonic growth and development due to the absence of primordial tissue. Agenesis of wisdom teeth differs by population, ranging from practically zero in Aboriginal Tasmanians to nearly 100% in indigenous Mexicans.
15. Black Hairy Tongue is a harmless condition that is often caused by an overgrowth of bacteria or using too many astringents. The tongue turns black and the taste buds grow longer than normal making the tongue appear to have long black hair.
Although the urinary bladder may hold as much as 600 ml of urine, the desire to urinate is usually experienced when it contains about 150 ml.
17. The cremaster muscle is responsible for moving your testicles up or down. It expands and contracts according to temperature by moving them further from the body when it’s warm and closer to the body when it’s cold.
18. Saxophone Penis a.k.a. Ram's Horn is the result of a blocked lymph node or a bacterial infection that leaves the penis swollen and twisted.
19. If a person receives bone marrow from someone who is a different ABO type, the recipient’s blood type will eventually convert to the donor's type.
20. Pain signals sent by an irritated diaphragm will be felt in the shoulder. The stabbing sensations near the heart that are sometimes felt after consuming a fatty meal are often confused with heart attacks but are nothing more than symptoms of indigestion, which can irritate one’s diaphragm.
21Absence of Bile
When the liver fails to produce bile, your poop doesn't get the regular brown pigments so it becomes white.
22. The act of vomiting involves a complex series of chain-link reactions by your body that connect to a "vomit center" in the brain. The lower digestive system in cases of perceived poisoning shuts down and causes the stomach to convulse in order to bring everything back up the way it came in.
23. Making predictions impedes the formation of memories. Trying to predict what is going to happen next in any given moment, impedes your brain’s ability to encode your current moment in memory.
24. Stomach aneurysms (abdominal aortic aneurysms) exist and can suddenly kill you much like brain aneurysms. The biggest modifiable risk factor for abdominal aortic aneurysms is not smoking. As long as you're not a smoker (less than 100 cigarettes in a lifetime), you're doing all you can to prevent it.
25. Unlike adult cataracts, which can be removed after years and normal eyesight is restored, severe pediatric cataracts must be treated within weeks or the brain will learn to permanently ignore the defective eye.