We filter out 99 percent of the sights, sounds, and other sensations around us if they don't seem threatening or important. If we didn't filter, the sensory overload would drive us insane.
We think we cannot see at night. But given enough time to adjust, the human eye can, for a time, see almost as well as an owl's. Ultimately, as the amount of light decreases, an owl detects shapes after a human no longer can.
Well-conditioned athletes commonly have low resting pulse rates in the range of 40 to 50 beats per minute. This compares with 70 to 80 beats per minute in the average adult.
In one day, the human brain generates more electrical impulses than all the telephones in the world put together. The nerve impulses can travel as fast as 170 miles per hour.
In one minute of breathing, the average human takes in 14 pints (6 liters) of air.
In one square inch of skin there are 3 yards of blood vessels, 3 million cells, 4 yards of nerve fiber, 1,300 nerve cells, and 100 sweat glands.
In one year, the average human heart circulates from 770,000 to 1.6 million gallons of blood through the body. This is enough fluid to fill 200 tank cars, each with a capacity of 8,000 gallons.
In the adult human body, there are 46 miles of nerves.
In the afternoon, your feet are bigger than at any other time of the day.
In the latter part of the eighteenth century, Prussian surgeons treated stutterers by snipping off portions of their tongues.
In the past few years, doctors have identified more than 100 sleep disorders, but the one most people suffer from is simply not taking the time to get enough sleep.
In the past one hundred years, the average American's lifespan has risen by more than 30 years.
In the past ten years, organ donors have saved more lives and improved the quality of living for more Americans than the United States lost in the Korean and Vietnam wars combined.
In the second it takes to turn the page of a book, you will lose about 3 million red blood cells. During that same second, your bone marrow will have produced the same number of new ones.
In the time it takes to read this sentence, 50,000 cells in your body will die and be replaced with new cells.
Innate immunity means you were born with an immunity to germ. Acquired immunity is gained by exposure to or immunization from a germ.
Iridescent beetle shells were the source of the earliest eye glitter ever used – devised by the ancient Egyptians.
It has been determined that one brow wrinkle is the result of 200,000 frowns.
It has been medically proven that pessimism raises blood pressure. The more pessimistic a person is, the more likely he or she is to die earlier than optimistic counterparts.
It has been proven that frequent laughter helps control pain, lower blood pressure, and relieve stress.
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