Tyler James5
Active Member
142 messages
joined Jul 2012
The human body doesn't need to get trashed to start rebuilding itself. Take red blood cells, for example—they’ve got about a 120-day lifespan, and after that, they're just... replaced. It's a constant stream of fresh cells following the blueprint of your existing DNA. So, how can they theoretically be the SAME old cells that died? They're simultaneously brand new and almost identical to the ones they replaced... kind of wild when you think about it.
(Trying not to sound like a total biology professor here, so I'm just gonna paste this catchy little article I found on the subject):
ONLY THE BRAIN AND EYES STAY OLD
Our organs are actually younger than we are
Over an average lifetime, your heart regenerates two or three times. Lung cells rebuild even faster than your nails or hair. In fact, there are only two parts of you that stay as old as your actual body: the brain and the eyes.
If you've ever wondered how some local heavy drinker can knock back massive amounts of booze and still be standing, just think about the liver's insane ability to bounce back. Liver cells only live for about 150 days—assuming cirrhosis doesn't catch up to them first, according to The New York Post.
And yeah, the heart can renew itself too. A study out of New York showed that certain heart cells rejuvenate, meaning the heart basically replaces itself two or three times over a person's life.
Cells deep inside the lungs regenerate once a year, while the ones on the surface move way faster—every two to three weeks. That is, unless you're a smoker dealing with emphysema. Diseases like that wreck those regenerative cells, basically punching holes in the lung walls.
Skin is also quick to refresh: every two to four weeks. But, obviously, as collagen and elasticity tank over the years, wrinkles eventually win the race.
Bones get a full overhaul every 10 years, but as the body ages, that whole process slows down. Bones get thinner and thinner, which is usually when osteoporosis starts making its move. Meanwhile, intestinal cells are constantly renewing every two or three days.
Even though nails grow about 3.4 millimeters a month, it takes much longer to fully replace them—anywhere from six to ten months (six for fingernails and ten for toenails).
Hair lifespan depends on how long you grow it, but it can last anywhere from three to six years.
Most cells that stick around for your entire life are tucked away in the brain, which doesn't really regenerate (though there is some research suggesting neuron regrowth happens within the brain itself), and those cells are gone for good once they pass. That's exactly why dementia hits so hard, and why brain injuries are so incredibly dangerous. Same goes for the eyes; they stay as old as you are, with only the cornea being able to regenerate. If the cornea gets damaged, it can fix itself in just 24 hours.
Author: T.T.
