Our Amazing, Renewable Body Parts Here's How Long It Takes to Regrow Your Own

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Many people
fret about ageing, little realising that whatever your age in years,
some of your body parts are just a few weeks, even days, old.

This is because
they are constantly renewing themselves.

LIVER AGE:
5 MONTHS

The liver is
known for its amazing capacity to repair and re-grow itself thanks
to its rich blood supply.

This means
it can continue with its main job of flushing toxins out of the
body.

If you’ve ever
wondered why even heavy drinkers can sometimes improve the state
of their liver, it’s because liver cells only have a life span of
around 150 days.

‘I can take
70 per cent of a person’s liver away in an operation and around
90 per cent of it will grow back within two months,’ explains David
Lloyd, consultant liver surgeon at Leicester Royal Infirmary.

However, in
heavy drinkers the parenchymal cells – the liver’s main cells – can become so damaged that scar tissue forms, a condition known
as cirrhosis. So though a healthy liver can regenerate itself, with
cirrhosis the damage is permanent – and sometimes fatal.

TASTE BUDS
AGE: 10 DAYS

The tongue
is covered with around 9,000 taste buds that help us to detect sweet,
salty, bitter or sour flavours, explains Professor Damian Walmsley,
scientific adviser to the British Dental Association.

The taste buds
themselves are a collection of cells on the surface of the tongue,
each housing about 50 taste cells. The buds renew themselves every
ten days to two weeks.

However, anything
that causes inflammation, such as infections or smoking, can damage
the taste buds and affect their renewal – deadening their sensitivity.

BRAIN AGE:
SAME AS YOUR AGE

Most of our
cells that last a lifetime are found in the brain, explains John
Wadley, consultant neurosurgeon at Barts and the London Hospital.

‘We are born
with all the brain cells we’ll ever have – around 100 billion – and most of the brain does not regenerate as it gets older.

In fact, we
actually lose cells, which is the underlying reason for dementia
and why head injuries are so devastating.

‘There are,
however, two areas of the brain that do regenerate,’ says Mr Wadley.
‘The olfactory bulb that governs our sense of smell, and the hippocampus,
which is an area for learning.’

HEART AGE:
20 YEARS

Until recently
it was thought the heart couldn’t renew itself. However, a study
at New York Medical College found it is actually dotted with stem
cells that constantly rejuvenate it – at least three or four times
over a lifetime, say the researchers.

LUNGS AGE:
2-3 WEEKS

The cells in
the lungs constantly renew themselves, explains Dr Keith Prowse,
vice-president of the British Lung Foundation.

However, the
lungs contain different cells that renew at different rates. The
alveoli or air sac cells – needed for the exchange of oxygen and
gases – deep in the lungs have a steady progress of regeneration
that takes about a year.

Meanwhile,
the cells on the lung’s surface have to renew every two or three
weeks.

‘These are
the lungs’ first line of defence, so have to be able to renew quickly,’
says Dr Prowse.

The lung disease
emphysema can prevent this regeneration as it begins with the destruction
of the alveoli, which creates permanent ‘holes’ in the walls of
the lungs.

EYES AGE:
SAME AS YOUR AGE

Your eyes are
one of the few body parts that don’t really change during your life.

The only part
that is constantly being renewed is the cornea, the transparent
top layer. If this is damaged, it can recover in as little as 24
hours, says Dr Rob Hogan, president of the College of Optometrists.

‘The cornea
has to have a smooth surface, so you can focus properly. That’s
why the cells renew themselves so quickly.’

Unfortunately,
this isn’t the case with the rest of the eye – as we age, the lens
loses flexibility, which is why we struggle to focus as we get older.

Read
the rest of the article

October
29, 2009

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