Understanding about your body

Understanding about your body

Your body is composed of between 50 and 100 thousand million cells.
A typical cell in the lining of your stomach lives only a few days.
You acquire a new stomach lining every five days (the innermost layer of stomach cells is exchanged in a matter of minutes as you digest food).
The skin’s cells multiply every second to replace those worn away.
A typical skin cell lives only two weeks.
Your skin is new every five weeks.
Your adipose tissue, (fat cells) fill with fat and empty out constantly, so that all of it is exchanged every three weeks.
A red blood cell lives longer – two or three months.
Your skeleton, seemingly so solid and rigid, is entirely new every three months.
Very long-lived cells can be found in the liver, where they take several years to replace themselves.
Heart and brain cells apparently last a lifetime without reproducing.
Every year, fully 98% of the total number of atoms in your body are replaced.
It has been estimated that if all the space was taken out of the atoms which make up the human body, the resulting mass
would be smaller in size than a pin’s head.
Your head weighs about 5kg (11 lbs).
Your scalp contains about 100,000 tiny holes called hair follicles, from which hairs grow.
The brain comprises 2% of body weight but accounts for up to 20% of the body’s energy needs.
A 1,000,000,000,000 (million million or billion) nerve cells or neurones are packed into every human head, almost 200
times as many cells as there are people currently inhabiting the planet.
There are as many stars in the Milky Way galaxy as there are cells in the brain. Each cell can be connected with up to
100,000 others.
Counting each nerve connection in the human brain cortex – the outer layer – at the rate of one a second would take 32
million years.
The number of interconnections that can be made between each brain cell is equivalent to infinite or the number one
followed by 6½ million miles (10.5 million km) of standard (11pt) typewritten zeros!
Even if we lose 10,000 brain cells a day from the time we are born, we have started with so many that the total number
lost by the age of eighty would be less than 3%.
It has been suggested that at any given moment there are between 100,000 and 1,000,000 chemical reactions taking
place in your brain.
A computer working at 400 million calculations per second would, operating for one hundred years, only accomplish
what your brain can accomplish in a minute.
More than half the human body weight is water.
We have between 2 and 3 million eccrine glands, which can produce up to 13 litres (3 gallons) of sweat on a hot day.
The number of living organisms on one person’s skin is approximately equal to the number of people on the planet.
By the time a baby is 9 days old the bacteria in the armpit will number at approximately 490,000 bacteria per 6.45cm2
(square inch).
Each human eye contains 130 million light receptors.
Our eyes can distinguish up to one million colour surfaces and take in more information than the largest telescope known
to man.

You blink your eyes about 20,000 times a day.

Each human ear contains 24,000 fibres.
The human body has 200 bones, 500 muscles and 11 kilometres (7 miles) of nerve fibres.
The human heart beats on an average 36,000,000 times each year, pumping 2,727,600 litres
(600,000 gallons) of blood each year through 150,000 kilometres (90,000 miles) of tubing,
arteries, veins and capillaries.
An average capillary is only 1mm (1/25th of an inch) long.
The combined surface of the capillaries totals 5016m2 (6,000 square yards), larger than a football field.
The blood circulating within the human body contains 22 thousand million blood cells.
Between 2 and 3 million blood cells die each second and are replaced by 2 to 3 million more.
One drop of blood contains approximately 5 million red blood cells.
Each lung contains 300-350 million alveoli (air bubbles).
The wall of each alveoli consists of a single layer of thin, flat, curved cells, only 0.0002mm (0.000008in) thick.
If all the alveoli from both lungs were spread flat they would cover an area nearly the size of a tennis court.
Our lungs inhale over two million litres (440,000 gallons) of air every day.
Each human body has four million pain-sensitive structures.
Throughout the human body there are 500,000 touch detectors.
When we touch something, we send a message to our brain at 199kph (124 mph).
There are 200,000 temperature detectors in the body.
Over 60% of the body’s nerve endings are in the forehead and the hands.
The human olfactory system, or sense of smell, can identify the chemical odorant of an object in
one part per trillion of air.

The highest recorded "sneeze speed" is 165 km (102 miles) per hour

We make one litre of saliva a day.
A human body with straight intestines would be nearly 10m (33ft) tall.
An area of the intestinal wall about the size of your fingernail contains almost 3,000 villi (finger-shaped structures).
On average, the human stomach holds about 2 litres (nearly half a gallon) of contents.
An average adult stomach processes about 500kg (1,100lb) of food each year.
The breakdown of a simple sugar, such as glucose, involves more than 50 reactions.
The liver has at least 600 different roles.
Inside the liver are up to 100,000 tiny clusters called lobules.
Your kidneys contain about one million tiny filters, called nephrons.
All the blood in your body passes through each kidney 400 times in one day, so about 200 litres (44 gallons) of water
and wastes are filtered.
Your bladder can stretch to hold about 400ml (0.7 pint) of urine. By this time you are busting to go!
The testis hold about 1,000 tightly coiled tubes known as seminiferous tubules. Straightened and joined, they would
stretch 500m (1,600ft).
About 500 million sperm mature every day.
The ovaries contain about 600,000 immature eggs at birth.