HOW OLD IS YOUR HAIR?
The hair on your head could be anything up to 6 to 7 years old
Each day your head hairs grow 0.5mm
Body hair grows more slowly, about 0.27mm per day
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Your eyebrows renew themselves every 64 days
YOUR ONLY BRAIN
Cells in the brain鈥檚 cortex are not renewed and are as old as you are, although there is evidence for continuous regeneration in the hippocampus
THE EYES HAVE IT
The surface of the cornea is covered in a thin layer of cells that is continually renewed. Complete turnover is every 7 to 10 days
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
SKIN DEEP
The surface of the skin is replaced every couple of weeks
Skin cells regenerate four times faster after a gentle injury, like ripping the top layer with sticky tape
THE NERVE OF IT
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 2 to 3mm per day
FAT CHANCE
The average age of a fat cell is 10 years
Each year 10 per cent of your fat cells are replaced
A LIVER ISN鈥橳 FOR LIFE
Liver cells turn over every 300 to 500 days
The human liver has an amazing capacity to regenerate itself. Remove up to 70 per cent 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 90 per cent of the liver, although recovery is incomplete
IT TAKES GUTS
The gut lining is replaced every 2 to 3 days
Some cells last longer 鈥� those that release antimicrobial fluid last 6 to 8 weeks
NAILED IT
Your fingernails grow almost 3.5mm each month, although the little fingernail grows more slowly than the others
Toenails grow at a rate of 1.6mm each month and the big toenail grows fastest
HEART OF THE MATTER
The heart is one of the least regenerative organs of the human body
A 25 year old turns over just 1 per cent of their heart cells every year, and this figure decreases with age
In the course of a normal lifespan, less than half of your heart cells are replaced
MOUTH TO MOUTH
Your taste buds are replaced every 10 days
THAT鈥橲 HANDY
Our fingertips can grow back after injury 鈥� 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
BREATH OF FRESH AIR
The lining of the bronchial tubes is replaced every 2-10 days
Microscopic air sacs called alveoli last 4 to 5 weeks
A RUSH OF BLOOD
Oxygen-carrying red blood cells are replaced every 4 months
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 10,000 cells every second
MIGHTY MUSCLE
The average age of a muscle cell is 15 years
THEM BONES
The skeleton is completely replaced every 10 years
This article appeared in print under the headline 鈥淢any versions of you鈥�