The human body really is miraculous. Every second of the day, it orchestrates a life-sustaining symphony of circulation, respiration, digestion, repair — and renewal — without one conscious intention from our brains. And by the time you turn 50, most of the components of your body have regenerated themselves, so that they are younger than the sum of your years. Read on for a selection of the most amazing things your body does every day.
We take many things that we can do with our bodies for granted – we walk, talk, and lift things without a second thought. When you get a cut, you probably slap a bandage on and go about your business. But the healing process deserves some more attention. Immediately after an injury, your body gets to work. Blood vessels at the site of the cut constrict to slow bleeding, and platelets hurry over, sticking together to help plug up the wound. Then clotting kicks in and keeps the platelets in place to stop the bleeding and start the healing. And all this occurs in minutes or even seconds!
You know that your stomach contains acid, but did you know that that acid is strong enough to melt through metals? The hydrochloric acid found in our gastric juices kills bacteria and helps break down proteins in the digestion process. It might seem strange that these acids don’t eat right through our stomachs, but our bodies instinctively protect themselves by constantly renewing our stomach-lining cells. The stomach lining renews so quickly – in five days – that the acid breaks down only food and not organs.
Nowadays, goosebumps do little more than signal that a) we're cold or b) we're experiencing an intense emotion. But evolutionarily speaking, goosebumps were integral to keeping us warm and scaring off nasty predators, the latter being a symptom of the "fight or flight" response.
Back when our species had hair all over our bodies, tiny muscles around the hair follicles would contract to make the hairs stand on end. Puffed out body hair provided better insulation than flat hair (keeping us warmer, if needed), plus it made our bodies look bigger and, hopefully, more menacing to ward off attack.
Did you know your mouth produces four to eight cups of saliva per day? And like most other bodily fluids, the spit in your mouth is irreplaceably useful. Thank saliva for your ability to taste and swallow food, speak (that's right!), and fight germs — the enzymes in saliva clean your mouth and prevent tooth decay. One more amazing factoid: Saliva contains opiorphin, which helps activate naturally occurring painkillers in your mouth and digestive tract, according to a 2013 study.
Our skeletons don't just grow as we age into adulthood — our bone cells are also constantly repairing and rebuilding themselves. Bones remodel so much that almost the entire skeleton is replaced every 7 years, according to the Stanford School of Medicine.
Because they are living tissue, bones also respond to our activity levels. If you get injured and aren't able to walk for a while, your bones will shrink correspondingly. But when you are healed and able to stand and do weight-bearing, your bone density will increase, says the American Academy of Orthopaedic Surgeons.
For years many scientists believed that the heart was one of the few organs in the body to remain static over a lifetime. Research from scientists at the Karolinska Institute in Sweden, however, showed that the heart does replace its muscle cells, albeit at a slow rate. Jonas Frisen, M.D., the lead researcher of the study, found that up until age 25, one percent of heart muscle cells are replaced each year, and that the rate of renewal slows as we age. Scientists now know that the heart we have now is different from the heart that we were born with.
It may not be as obvious as a snake shedding it's entire outer skin in one piece, but you might be surprised to learn that the skin you have now is entirely different from the skin you had a month ago. The top layer that you see is just dead skin cells, and new skin cells from the bottom layer are constantly making their way up to replace the top. Every human sheds 500 million skin cells every day and replaces her entire set of skin cells every 35 days — that's roughly 10 spankin' new skins a year and nine pounds of shedded skin.
Millions of times a day, a naturally occurring enzyme in your body saves you from cancer. Here's the story: Each of the 100 trillion cells in your body contains a set of your genetic material, and when your cells divide in a natural cycle that happens every 24 hours, they replicate your DNA so it's included in the "daughter" cell, too. Researchers have found that 120,000 mistakes occur during each DNA replication, and if not for a "proofreading" enzyme called RNase H2, those errors would almost certainly lead to cancer and other genetic diseases. RNase H2 prevents disease by sniffing out and repairing genetic mistakes that might otherwise flourish.
Every day, your kidneys (which are about the size of your fist) filter 50 gallons of blood and deliver about 1/2 gallon of waste and water to your bladder for removal. In other words, every 30 minutes, your kidneys filter all the blood in your body to remove toxins that could make you sick.