"Everything old is new again." You know that old saying? It's especially true of the human body.
I'm a total geek about health and science - seriously. And I have no idea where I got that or why. But I read an article recently on New Scientist (subscriber only, see? GEEK!) about how fast the cells in your body re-grow and replace themselves - and was totally amazed at how speedy it is. In fact, in an average adult, the vast majority of their cells is only 7 to 10 years old - so you're not as old as you feel :)
And all this new cell info is incredibly hopeful too. I mean dang, in just a few days you can have a totally new intestinal lining. And you can grow back almost your entire liver, though that's not an excuse to have that extra glass (or five) of wine later.
I did a little more researching and came up with a bit of a list for body parts and how quickly they turn over, just to share with y'all.
- The hair on your head could be anything up to old.
- Each day your head hairs grow 0.5mm.
- Body hair grows more slowly, about
- Your eyebrows renew themselves every
- The surface of the cornea is covered in a thin layer of cells that is continually
renewed. Complete turnover is
- Cells in the retina do not regenerate, which is why vision problems arise with age. However, stem cell treatments are beginning to target degenerating retinas.
- Researchers have managed to regenerate rods, the photoreceptors that capture dim light. But only in a Petri dish, so far.
- The epidermis or surface of the skin is replaced
- Skin cells regenerate four times faster after a gentle injury, like ripping the top layer with sticky tape.
- Damaged nerve cells can regrow to some extent, as long as the nerve cell body is intact.
- The rate of nerve regeneration after injury is thought to be around
- The average age of a fat cell is
of your fat cells are replaced.
- Liver cells turn over every
- The human liver has an amazing capacity to regenerate itself. Remove up to of the organ and it will grow back to its normal healthy size in as little as a couple of months.
- Surgeons have even removed as much as of the liver, although recovery is incomplete.
- The epithelial cells or surface of the gut lining is replaced
- Some cells last longer – those that release antimicrobial fluid last
- Your fingernails grow almost
- Toenails grow at a rate of and the big toenail grows fastest., although the little fingernail grows more slowly than the others.
- The heart is one of the least regenerative organs of the human body.
- A 25 year old turns of their heart cells , and this figure decreases with age.
- In the course of a normal lifespan, less than half of your heart cells are replaced.
- Your taste buds are replaced
- Our fingertips can grow back after injury – at least partly.
- The best results are seen in children, who can regenerate a new fingertip within a few months. But it works for adults too.
- For this to happen, you need an intact nail bed. The new fingertip has sensation and a fingerprint too.
- The lining of the bronchial tubes is replaced every
- Microscopic air sacs called alveoli last
- Oxygen-carrying red blood cells are replaced
- The most common type of white blood cell, neutrophils, only last for a few hours.
- Another important type called lymphocytes are replaced at a rate of
- The average age of a muscle cell is
- All your bones, the whole skeleton is completely replaced
All really cool stuff, eh? I'm hoping it inspires me to eat healthier and grow healthier new cells every second that I'm breathing.