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Transcript
00:00Unit 3. Our human body. A wonderful machine. Just as a house is supported by concrete pillars,
00:15a mandap is supported by a bamboo structure, an umbrella is supported by the metal ribs.
00:25Similarly, our body is supported by a bony structure called the skeleton. It gives us
00:35strength and also protects our delicate organs.
00:41Cells to Organ System. Cells. Look at this house. It is made up of a number
00:52of bricks. Similarly, our body is made up of millions of tiny units called cells. All
01:03living things are made up of cells. Tissues. Cells of similar type join together
01:13to form a tissue. There are many types of tissues on the basis
01:21of different types of cells they are made up of. The tissues that make up the muscles
01:29are different from the tissues that make up the bones.
01:35Organs. Different types of tissues join to form an
01:40organ. Eyes, Nose, Tongue are organs that are made
01:50up of tissues that help us to see, smell and taste.
01:58A football game can only be won if all the players play it in a coordinated manner.
02:10Similarly, our body organs also need to function in a coordinated manner for us to live a healthy
02:23life. When a group of organs cooperate with one
02:30another to carry out a function of the body, we call it an organ system.
02:43Look at this diagram showing the journey of a cell to form an organ system.
02:51Now let's look at the organ systems in our body and how these systems function.
03:01The Digestive System. Our body cannot use the food in the form we
03:07eat. It has to be broken down into simple substances.
03:14This process of changing the food into simpler substances is called digestion.
03:24Process of Digestion. Mouth. The process of digestion starts in the mouth.
03:34We chew the food with our teeth. As we do so, a juice is secreted in the mouth.
03:42This juice is called saliva. Saliva mixes with the food and makes it soft.
03:51The more you chew your food, the better it mixes with saliva.
03:57The food is partially digested here. After the food has been chewed properly, you
04:03swallow it. It goes down a tube called the food pipe.
04:13The food pipe carries the food to the stomach. Stomach. The stomach is like a muscular bag.
04:26The walls of the stomach secrete other digestive juices.
04:32These juices help to change the chewed food into simpler substances.
04:39From the stomach, the food goes into the small intestine.
04:47Small Intestine. It is a long coiled tube. Some more digestive juices mix with the food
04:56here, digesting it completely. The walls of the small intestine absorb the
05:03digested food and pass it on to the blood vessels. The blood vessels carry the digested
05:11food all over the body, supplying it with nutrition. Some parts of the food are not
05:20digested. This undigested food reaches the large intestine.
05:30Large Intestine. The walls of the large intestine absorb the
05:35water and the rest of the undigested food is released from the body through the anus.
05:44Digested food should leave the body, otherwise it will harm your health.
05:52That is why you should develop regular toilet habits.
05:59The Circulatory System. The circulatory system consists of the heart
06:06and blood vessels. Your heart is the size of your fist.
06:13The heart works just like a pump. It pumps blood to all parts of your body.
06:24Put your hand on the left side of your chest. What do you feel?
06:31This is your heart pumping blood. There are three types of blood vessels in
06:38the human body. Arteries and veins are large blood vessels
06:44and capillaries are thin hair like blood vessels. Blood makes up to about 7% of body weight
06:54for a normal healthy adult. You must have seen doctors use an instrument
07:01called stethoscope. They use this instrument to listen and count
07:08your heartbeat. Heart of an adult beats 72 times per minute.
07:16Pulse is the measure of heartbeat. Place two fingers on your wrist just below
07:25the thumb. You can feel the pulse if you press your
07:29fingers a little.
07:33Unit 3. Our Human Body.
07:38A Wonderful Machine. Process of Circulation.
07:47Blood carries digested food and oxygen to each and every cell of the body.
07:55It also carries back carbon dioxide and waste material back to the heart.
08:03The heart sends this impure blood to the lungs to be purified.
08:11Arteries generally carry pure blood that contains oxygen from the heart to different
08:16parts of the body and the veins usually carry impure blood that contains carbon dioxide
08:24back to the heart. This goes on continuously even when you are
08:35sleeping.
08:38Human Respiratory System. All living things breathe air.
08:45We breathe in and breathe out through our nose.
08:51The nose has fine hair which trap dust particles. You must always breathe through your nose
09:00and not through your mouth. This prevents dust from entering your body.
09:10The respiratory system consists of the nose, the windpipe and a pair of lungs.
09:21As you breathe in through your nose, air containing oxygen goes in.
09:27Through the windpipe it reaches the lungs. The windpipe connects the nose to the lungs.
09:38Lungs are made up of thousands of air sacs which look like bunches of grapes.
09:47Each air sac is surrounded by blood capillaries. There is an exchange of gases between air
09:56sacs and blood capillaries in the lungs.
10:03Process of Respiration. Impure blood is brought from the different
10:09parts of the body to the heart. From the heart it goes to the lungs.
10:18As you breathe, the air containing oxygen reaches the air sacs in the lungs and the
10:25blood takes up oxygen from the air sacs and releases carbon dioxide.
10:33The air sacs must contain carbon dioxide. This carbon dioxide leaves your body as you
10:43breathe out. This process goes on continuously and is called
10:50breathing. The oxygen helps to release energy by burning
10:57the digested food in every cell. This process is called respiration.
11:09Remember to follow these healthy habits. Breathe through your nose.
11:18Try to get as much fresh air as you can. Physical exercise is the best way to build
11:26a strong and healthy body. Play games as exercise helps you to breathe
11:33more deeply and you get more oxygen. Do not sleep with your face covered as you
11:42will not be able to breathe fresh air.