Download Your Body, by the Numbers

The adult brain contains 100 billion neurons — more than the number of stars in the
Milky Way galaxy. Each of the brain's neurons connects to as many as 200,000 other
neurons.
At three pounds, the brain makes up only 2 percent of total body weight but consumes
about 15 percent of the energy used by the entire body.
Nerve impulses carrying images from your eyes to your brain travel at almost 400 feet
per second. (The speed of light is 186,000 miles per second.)
The average man has about 16 square feet of skin that weighs between nine and 15
pounds.
Each square inch of skin contains several hundred sweat glands, blood vessels, nerve
endings and oil glands. The sweat glands number more than 2 million overall.
Skin is thickest — about 1/5 inch — on the soles of the feet and the palms of the hands.
It is thinnest on the scalp.
Fingernails grow about one millimeter (0.04 inch) every 10 to 15 days. It takes them
about six months to grow from the nail bed to the tip of the finger. Nails grow faster on
your favored hand and on your longer fingers.
Millions of dead skin cells are replaced each day with new ones. A cell's life lasts
about 10 to 30 hours total.
There are five liters of blood in the adult human body, which is about 7 percent of your
total body weight. The entire blood supply makes a complete circuit of the heart, lungs,
blood vessels, and back to the heart every 60 seconds.
There are four major blood types, O, A, B and AB. Nearly half the population is type
O, and they can donate blood to people with all other blood types but can only receive
type O blood. The rarest blood type, AB, is present in about 4 percent of the
population. These people can receive all types of blood.
There are about 75 to 100 trillion cells in the body, about 25 trillion of which are red
blood cells. An individual red blood cell contains about 250 million molecules of the
iron-containing protein called hemoglobin, which is capable of picking up four
molecules of oxygen. As a result, a single red blood cell can deliver up to 1 billion
molecules of oxygen.
Laid end-to-end, the arteries, capillaries and veins in the average child would stretch
for about 60,000 miles and, in the average adult, would be about 100,000 miles —
enough to wrap around the world at least twice.
At about 11 inches long and nearly 6 inches wide, the lungs together weigh only about
two pounds. They contain about 1 1/2 gallons of air.
The inside of your lungs is covered with 300 to 600 million tissue-thin sacks called
alveoli. Stretched out flat, the alveoli would cover a tennis court.
Each day, the average adult inhales about 4,250 gallons of air, containing about 40
billion trillion molecules of oxygen. Along with it comes about 20 billion particles of
dirt and other foreign matter.
When you cough, the air rushing out of your lungs hits speeds of 75 to 100 miles per
hour.
The nose traps and filters up to 70 percent of the 20 billion dust particles that are
inhaled each day. It also changes the temperature of the incoming air to about 95 F and
regulates humidity up to 100 percent.
Each year, people living in the United States catch almost 1 billion colds. That's about
two to four colds for each adult and six to eight colds for each child. The reason: There
are more than 100 different rhinoviruses, the most common cold-causer, plus about 90
other kinds of cold-causing viruses.
The fastest sneeze ever recorded was clocked at just over 100 miles per hour.
Your nose contains 20 types of odor-detecting cells. With these, you can distinguish
thousands of different smells.
The tongue has 3,000 to 10,000 taste buds. Although the tongue can perceive hundreds
of different tastes, the taste buds generally detect only sweet, sour, bitter and salty.
The mouth produces about a quart of saliva each day.
Despite its diminutive name, the small intestine is actually the longest part of the
digestive tract, stretching some 22 feet in length. The large intestine, however, is just
five feet long. The names, small and large intestine, refer to their width, not length.
When full, the stomach holds between a quart and a quart and a half of food and
liquids. And it takes about four hours for the stomach to fully digest a meal and pass it
along to the small intestine. Food passes through the small intestine in just four hours,
zipping along at more than a half an inch per second. Inside the large intestine, it takes
about eight to 15 hours, traveling at a more leisurely rate.
The inside of the small intestine, which absorbs the digested proteins, sugars and fats
from food, is covered with a furlike layer of tiny projections called villi and microvilli.
This food-absorbing "fur" boosts the surface area by 600 to 1,000 times, compared to
what a smooth interior surface would provide. If the interior of the small intestine were
smooth, it would have to be more than 1 mile long to provide the same food-absorbing
power as its present 22 feet.
Each day, about three gallons of food, liquids and digestive juices gurgle through the
digestive tract. Only about half a cup emerges as feces.
Almost half of your body is muscle. There are more than 650 muscles, and they make
up about 50 percent of total body weight.
The biggest muscle in the body is the gluteus maximus - the butt. Each of these two
muscles tips the scales at about two pounds (not including the overlying fat layer). The
tiniest muscle, the stapedius of the middle ear, is just one-fifth of an inch long.
Most cells in the body are microscopic in size, but muscle cells, also called muscle
fibers, can be up to 1 foot long and visible to the naked eye.
When you're born, you have 270 bones. But an adult has only 206 bones. Why so?
Many bones, such as those that make up the skull and spine, fuse together as you grow.
Most people have 12 pairs of ribs, but about 5 % of the population has an extra pair.
The tiniest bone in the body is the stirrup bone in the ear, which is less than an inch
long. The longest bone is the femur, which varies in length from person to person but is
about one-fourth of a person's overall height.
Hand over foot: There are 54 bones in all in your wrists, hands and fingers but only 52
in both feet, ankles and toes.
-- Courtesy : http://www.intelihealth.com