Saturday, May 5, 2012

Basic information about human body


THE HUMAN BODY           
You have seen many wonderful things man has made. Can you name some what you have seen recently? None of the things you can name are as wonderful as the human body. The part of the body that guides and directs it is the brain. Do you see why the brain must be protected against damage? You can tell that a bony layer lies beneath the hair and skin of your head. You can feel it. Your brain is protected by this layer of bone. This layer of bone is part of the skull. Are other important parts of your head protected by these layers of hair, skin and bone? Can you name some?            

Your heart and lungs also lie within a bony framework. This bony framework is your chest. It, too, is covered by layers of skin and of flesh. How do these layers protect the bones that lie beneath them? Your skin and hair, the layers of flesh beneath the skin and the bony framework of your body protect vital parts. But your body has other forms of protection. Its ability to avoid harmful things is one of its best defenses. All of your senses, for example, give warnings of possible dangers. You use these warnings in deciding what action to take to avoid getting hurt. Sometimes your body takes action before you are able to think about what to do. Your eyelids, for example, close immediately when a fast-moving object comes toward your eye. Your hand is immediately jerked away from a hot object. Think of other things your body does to protect itself, even before you think about what to do. Some of the things that can harm your body are very small. These you can see only under a powerful microscope. Some of these things are non-living. Some are living and are therefore either plants or animals. Many of the tiny things that can be harmful are called germs.             

Your body has forms of protection against germs. But sometimes the germs overcome some of the defenses of the body. They get inside your body. There they live, grow and produce more of their own kind. They begin to harm the body. Warning signals are sent to the brain. Sometimes these signals are pain signals. There may be other signals too. These include fever, chills and sneezing. As warning signals reach the brain, other body defenses go to work. They must overcome the germs. Otherwise, great damage may be done.

 
HOW SENSE ORGANS ARE USED            
Most of the foods you like are foods that your body needs for growth and energy. Your senses are important in the selection of food.               
Your senses not only help you choose foods your body needs; they also help you avoid foods that may be harmful. Meat that has begun to spoil often has a bad odor. It may also have a bad taste. Sometimes it may even look unfit to eat. Disturbances relayed to your brain from nerve endings in your sense organs can help protect you from food that may be harmful. Of course, you are only warned by senses. You must still decide what to do about the warnings.              


SAFEGUARD AGAINST INJURY          
The smell of wood smoke within a room may cause you to become alarmed. The gases and particles given off by the burning wood go into the air. They reach your nose. Some of the nerve endings there set up disturbances which are transmitted to your brain. You become aware of the smoke and think of fire. You may decide to do one of several things. Perhaps you will decide to give an alarm for others to hear. Or you may see a smoking log in the fireplace and decide that there is no reason to become alarmed. Perhaps you will decide to go into the open air. You will certainly do whatever is necessary to protect yourself from harm. Whatever you decide will depend a great deal upon what you learn through your senses.             
All about you are things that could harm your body. You become aware of these things because the nerve endings in different sense organs become disturbed by the light, sound, odor, or touch of these things.                   
Sometimes the amount of disturbance of the sense organs is great enough to cause harm to the sense organs themselves. Then your body defenses take over. Suppose, for example, that a fast-moving object comes toward you. Your sense organs are disturbed by its sound and appearance. You may duck or dodge. Your eyelids may close. Perhaps you will cover your ears with your hands.            



PROVIDING PLEASURES            
Have you rubbed the soft fur of a kitten? Did the kitten's fur feel pleasant to your touch? What are some other pleasures you enjoy because of your sense of touch?                   
Each of your senses provides you with pleasant experiences. You enjoy seeing the face of a friend. You also enjoy seeing a beautiful sunset or picture. Smelling the odor of a cake being baked is also enjoyable. Many people find music pleasing. Which of your senses do you use when enjoying music?              



 

EYES: Look at the eyes of one of your classmates. Notice how the eyes are set in the head. Is it possible to strike a person over his eye without touching the eye itself? Feel the hard bony surface that lies beneath the skin that surrounds your eyes. Do you see that the eyes are well protected against blows? What other natural protection do your eyes have? Did you name the eyelids, eyebrows, eyelashes and tear glands?           
What other things besides moving objects can harm the eyes? Do you know that too much light energy can be harmful? For this reason avoid looking directly at very bright lights. Sun lamps and heat lamps can also be harmful to the eyes. For this reason do not look directly at them. Because the same type of energy comes from the sun, you should not look directly at the sun.                





NOSE: Which of the nerve endings that lie within your head have the least protection? Might they be those of your sense of smell? Where are these nerve endings? Do you see why baseball catchers wear masks? Do you see why players in other sports also are encouraged to wear nose guards?                 
The nose and all of the other sense organs have natural protections. These protect against many dangers which might cause damage to the sense organs. You can add to the natural protections by doing everything possible to give proper care and protection to your sense organs.

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