Video 4 Myelty

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Unit 4. The human body

The human body. No machine can match the feats it performs every day.
Our lungs suck in 70 quarts of air each minute when we exercise…
Our hearts pump two thousandgallons of blood each day…
And more than 600 muscles keep us moving, in every direction.
Like all living things, human beings are made up of cells – 100 trillion of them.
Individual cells areorganized into tissues… like this heart muscle tissue.
Different kinds of tissue form an organ, such as the heart. And several organs working together create an organ system.
Each of the 10 major organsystems in the human machine performs a special job.
The circulatory and respiratory systems supply energy 24 hours a day.
The heart works automatically, and incredibly hard. No other muscle in thebody is as strong.
It beats 100.000 times a day… 36 million times a year, sending blood on a complete trip around the body in less than a minute.
The lungs pull in oxygen form the air, deliveringbreath through 15 hundred miles of airways.
All this work is fueled by food… And turning pizza into useable molecules is the job of the digestive system.
Swallowing sends food down the esophagus intothe stomach.
Like a blender, the stomach contracts to break it down, helped out by acid and enzymes.
This liquefied food travels into the small intestine, which can be over 20 feet long, where mostnutrients enter the bloodstream…
And the brains of this whole operation – is the human brain.
A wrinkled blob about the size of a grapefruit, it’s the most complex object on earth.
The braincontains up to 100 billion neurons, or nerve cells.
Neurons send signals rocketing through the brain at over 200 miles an hour.
The brain, spinal cord, and nerves make up the nervous system – and all worktogether to control the body’s activities.
The reproductive system creates new life.
Each human begins as two single cells – and egg cell from the mother, and a sperm cell from the father.
When...