Cell and number

Cells and related numbers in our bodies

hair
 

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.
Your eyebrows renew themselves every 64 days.

YOUR ONLY BRAIN Cells in the brain셲 cortex are not renewed and are as old as you are, although there is evidence for continuous regeneration in the hippocampus.

petri-dish

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.

SAME BUT DIFFERENT

We all spent the first 30 hours of our lives as a single cell.
Babies born with teeth are rare only 1 in 1000 by the highest estimates.
Some 6 percent of people have an extra nipple. They tend to occur on the left side of the body and are more common in men.
Each day your blood travels a total of 19,000 kilometres half the circumference of Earth.
Messages travel along the fastest neurons at 400 kilometres per hour faster than a Formula 1 racing car.
A handful of people go through life with no fingerprints, thanks to a rare gene variant, a condition dubbed immigration delay disease.

neuron

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 3 mm per day.

FAT CHANCE

The average age of a fat cell is 10 years.
Each year 10 percent of your fat cells are replaced.

A LIVER ISN셏 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 percent 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 percent of the liver, although recovery is incomplete.

IT TAKES GUTS

gut
The gut lining is replaced every 2 to 3 days.
Some cells last longer those that release antimicrobial fluid last 6 to 8 weeks.
Source : NewScientist the Collection Vol.2.
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