Human Body-A Wonderful Machine

What is our body made up of?

Just as thousands of bricks are used to build a house.Our body is made of millions of tiny cells.Our whole body is supported by a bony structure called the Skeleton.

All living things are made up of cells-plants as well as animals.while most creatures are made up of many cells.there are few single celled creatures like the tiny microscopic amoeba.there are many types of cells.

• Tissues:similar types of cell join together to form a tissue.just like the bricks are joined together to form a wall,cell of similar type join to form a tissue.Tissues are also of many types.The tissues that make up the muscles are different from the tissues that make up the bones.
• Organs:Different types of tissues join to form an organ.If you are asked,"which sense organ helps you to smell?you"ll immediatelysay"Nose" but if you will be asked "which organ helps in digesting your food? i think you'll get a bit puzzeled.No sinle organ can carry out the process of Digestion. The task is so big that one single organ can not carry it out alone.its a Group of organs carry out this function all together.the organs cooperate with each other in a perfect manner to carry out this important process.This is a perfect example of "Team Work" When a group of organs cooperate to carry out a function of the body,we call it an organ system. chart chart lets now look at a few organ system in our body and how these function.
• Blood:As well as organs,a human body contains upto five litres of blood.your heart pumps blood around your bodyalong thousands of tubes calles "blood vessels".As it flows along,blood delivers oxygen and food to every part of your body.
• Skin:Your skin gives your whole body a waterproof covering and protects your insides from dirt and germs.skin is made up of two main layers.The top layer of skin is called the epidermis and underneath the epidermis is a thicker layer called the dermis which is hair shaft.
• Bones and Muscles:Bones and muscles are your bodys support system.

    Your skeleton-All the bones in your body together make up
your skeleton,which acts as a framework for your whole body.Bendy joints where bones meet let you move into different positions.

    Muscles-The bones of your skeleton are moved by muscles.These help you move in all kinds of ways.Muscles work by contracting.As a muscle contracts,it pulls on the bones its joined to,and they move.

The Digestive System:

you know that all living things need food and water.what happens to the food we eat and the water we drink? Our body can not use the food we eat as it is. it has to be broken down into simple substance which are soluble in water.This process of changing the food into simpler substances is called digestion

• Mouth : the process of digestion starts in the mouth.We chew the food with our teeth.As we chew the food a juice is secreted in the mouth.This juice is called saliva.saliva mixes with the food and makes it soft.The more you chewyour food,the better is the mixing with saliva.the starch in the food is then changed to sugar.After the food is chewed properly,you swallow it.It goes down a tube called the food pipe.The food pipe carries the food to the stomach.
• Stomach:the stomach is like a muscular bag.The walls of the stomach secrete another juice .This juice helps to change the chewed food into simpler substances.From the stomach the food goes into the small intenstine.
• Small intenstine-It is a long coiled tube.Some more juices mix with the food here.Then walls of the small intenstine absord the digested food and pass it on to the blood vessels.The blood vessels carry the digested food all over the body,supplying it with nutrition.some parts of the food are not digested.This undigested food reaches the large intenstine.
• Large intenstine: The wall of the large intenstine absorbs the water and the rest of the undigested food is thrown out of the body through the anus.

Points to remember: The wate food should leave the body,otherwise it will harm your health.That is why you should ndevelop regular toilet habits.

Fill in the blanks with correct alternatives:

1. The process of digestion begins in the ______________.(stomach/mouth) 2. Similar types of cells join together to form______________.(an organ/ a tissue)

3. The walls of the small intestine absorb the _________________.(water/digested food)

4. waste food is stored in the _______________(large intenstine/small intestine)

5. Saliva is secreted in the ____________(stomach/mouth)

 

The Circulatory System:

The circulatory system consists of the Heart and Blood Vessels.

put your hand on the left side of your chest.what do you feel ?This beating is from your heart.Your heart is the size of your fist.the heart is like a pump.It pumps the blood to all parts of your body.It works 24 hours.

There are three types of blood vessels that carry blood around your body.

The Arteries and the veins are large blood vessels and capillaries are thin hair like blood vessels. Arteries generally carry pure blood from the heart and the veins usually carry impure blood back to the heart.You must have seen doctors use an instruments called "stethoscope".They use this instrument to listen to your heart beat.

• What is pulse?

Pulse is the "heart beat".Place three fingers on your wrist just below the thumb.You'll feel your pulse.

• What is the function of the blood?

Blood carries digested food and oxygen to all parts of your body,to each and every cell.It also brings back the waste(impure blood)produced in the cells,back to the heart. The heart sends this impure blood to the lungs to be purified.this goes on without any break.even when you are sleeping,The heart and the lungs keep on working to keep your body fit.

The Respiratory System:

All living things breathe.We breathe in through our nose.

Nose:It has fine hair,which trap dust particles and very tiny insects.So always breathe through your nose and not through your mouth.

The respiratory system consists of the nose,winepipe and a pair of lungs.As you breathe in through your nose,air(containing oxgyen)goes in.Through the windpipe it reaches the lungs.

The lungs are made up of thousands of air-sacs,which look like bunches of grapes.Each air-sac is surrounded by capillaries.These capillaries contain impure blood brought from the heart.As the air containing oxygen reaches the air -sacs,the capillaries release carbon dioxide and absorb the oxygen.There is an exchange of gases in the lungs.The air-sacs now contain carbon dioxide.This carbon dioxide leaves your body,as you breathe out.This process goes on continuously.

Frequently asked qustions on respiratory system for kids:

• Name the organs of the respiratory system?
• Where does the exchange of gases take place?
• Why should we always breathe through our nose?

Note:Normally ,we breathe about 75 times in a minute.

We have other systems too in our body,besides the systems mentioned here. these are:

The Excretory System:

This system helps to throw out the waste products produced in our bodies,in the form of urine,excreta and sweat.

The Nervouse System:

This sytem controls and co-ordinates all the other systems.

The Reproctive System:

This system helps to reproduce young ones and babies.