Tecchilaw - 10. Let us discover our body

Your body is the most valuable asset you own. The body consists of the sense organs such as eyes, ears, nose and skin and various systems to help in its functions. It is your duty and responsibility to protect it and keep it healthy. It is important for you to understand how your body is organized and how it functions.

In grade 6 you learned how to protect your sense organs; eyes, nose, ears and skin.

Think of some activities that you may engage in every day. Walking, running, clapping, jumping and breathing are a few of these. What are the systems that help you to engage in these activities?

Because of the muscles and bones in your hands and legs,you are able to walk and run. Have you ever thought how your muscles got the strength to do what they do?

While you were doing the above activity you must have realised that your breathing and heart beat increased. The nervous system carries the message from your brain to your legs, that you have to run. During running the necessary energy for the muscles is received from glucose and oxygen. These are taken to the muscles through the circulatory system. The digestive system supplies the glucose to the blood and the respiratory system supplies the oxygen to the blood.

You may have realised by now that many systems are involved actively and collectively even in a simple activity like running. In order to maintain the body functions, different systems work jointly and collectively.

What do you mean by 'an organ system'?

Many different organs in the body working together to perform a physiological function or process is known as an organ system.

Think of a car for example. If the car is your body the engine is one of your systems. The different parts of the engine such as the piston and the valves can be compared to our organs. Each of these parts has a special function to fulfil.

But all these parts together that form the engine help it to start. The same way, the various organs in the different systems of the body work together to perform a task. For example, the different organs in the digestive system work together to execute the process of digestion of food.

Given below are the functions of some of the different systems in our body.

If the function of any of the above systems is impaired, one will fall ill affecting normal day to day life. Therefore we have to be careful and protect ourselves well.

The function of the digestive system is to break down the solid food into smaller particles and absorb the nutrients such as glucose into the blood stream and thereafter discard the waste matter produced in semi solid form. The food so absorbed is necessary for the growth of the body, to protect us from diseases and to supply energy required for various activities.

Look at figure 10.1. You can see that the digestive system is made up of different organs.

Mouth

The teeth in the mouth are capable of breaking and grinding even hard solid food. In grade 6 we learnt that children have 20 deciduous teeth and adults have 32 permanent teeth.

The food broken down by the teeth into smaller pieces are mixed with saliva produced by the salivary glands. Thereafter the tongue while making you feel the taste of food, helps in swallowing it, pushing the food down the pharynx.

The nose cavity and the mouth cavity open into the pharynx. The oesophagus and the larynx start from there. When swallowing the food the epiglottis covers the larynx and prevent food passing into the trachea. The swallowed food moves down the oesophagus. When you talk while eating this process does not happen properly and the food accidentally enters the trachea causing you to choke. This is colloquially referred to in Sinhala as ''Ismolle yama'' or ''pita ugure yama''.

Stomach

The food travels through the oesophagus and enters the stomach. The stomach is a sack made up of muscles that can expand gradually. Muscle action in the stomach causes the food to breakdown further.

The digestive juices secreted by the salivary glands, the wall of the stomach, the liver and the pancreas help to digest the food. The bile produced by the liver is stored in the gall bladder.

Small intestine

The small intestine is a narrow but long tube. The main part of digestion takes place in the small intestine. The digested food is absorbed almost entirely here.

Large intestine

After the absorption of nutrients in the small intestine, the water contained in the food and minerals are absorbed in the large intestine. The semi solid waste left over is known as faeces.

At the place where the small intestine meets the large intestine there is a small tube shaped sac which is known as the appendix.

Rectum

The faeces are temporarily stored in the rectum. The rectum can control the process of defecation

What you should do to keep the digestive system healthy?

1. Take meals at the correct time

Sometimes when you are late to school, you may skip your breakfast. When that happens, your brain does not get enough glucose making it difficult for you to concentrate on your work. Therefore it is important that you take your meals at the correct time for the proper function of your body.

2. Take meals with proper nutritional value

You have learnt the importance of a balanced diet in lesson 12. It is important that you take a meal balanced in nutrition for growth and prevention of disease.

3. Take more natural foods and beverages

Preservatives, food colourings, sweeteners and additives are sometimes used in the production of certain instant and precooked foods and beverages. When these are taken in large quantities it can be harmful to the body. Therefore it is advisable that we consume natural fruits and vegetables and avoid artificial food.

4. Take clean food and drink sterilized water

You can contract diseases such as diarrhoea, cholera and typhoid if you eat food contaminated by flies or drink polluted water. By eating food stored cleanly and drinking water boiled at least for one minute at the boiling temperature and filtered, these diseases can be minimized.

5. Take food rich in fibre

We can prevent constipation and bowel (intestinal) cancer by eating food rich in fibre.(Fruits, vegetables and greens-leafy vegetables)

6. Minimize the consumption of oil, salt, chillies and wheat flour

Excessive consumption of the above mentioned items of food can cause obesity, high blood pressure and discomfort in the stomach.

7. Drink enough water

Water is very important for the digestion of food and proper maintenance of blood circulation. You can prevent dehydration by drinking plenty of water. You learnt this in lesson 12 of this book.

8. Protection of your teeth

Teeth are very important to break food into small pieces, to speak and to have a pleasant appearance. Breaking food into small pieces helps in the digestion of food and prevents choking. You must brush your teeth at least after the three main meals to prevent decaying of teeth. You must use a suitable brush and toothpaste for this purpose. At least every year you must get your teeth examined by a dental surgeon.

9. Develop good bowel habits

Constipation can be prevented by passing stools when the urge arises and having regular bowel habits. Seek medical advice if there is a change in the normal movement of bowels.

10. Prevention of diseases caused by worms

Diseases caused by worms can be prevented by using toilets with proper sanitary facilities and by developing good health habits. Use footwear when walking outdoors to prevent getting infected by hookworms. Diseases caused by worms can be minimized by taking worm treatment. There is a programme to supply worm treatment annually by the Ministry of Health.

11. Avoid smoking, drinking alcohol and chewing betel

To prevent oral cancers and cirrhosis, you should avoid such things.

The function of the respiratory system is to transport oxygen from the atmosphere into blood and release carbon-dioxide from blood into the atmosphere.

Oxygen is necessary to produce energy. Although we can live for a day or two without water and food, we cannot live without oxygen for more than a few minutes. The oxygen absorbed by the lungs is taken to various organs and cells of the systems through the blood. The carbon dioxide formed in the process of producing energy, is taken back to the lungs by blood. Respiration is this process of exchanging gases in the lungs and transporting these gases between the lungs and other organs of the body, through the blood stream.

The process of taking air into the lungs is known as inhalation while, the process of exhaling air from the lungs is known as exhalation. Inhalation and exhalation together is known as breathing.

Nose

In the nose, there are small hair like projections called cilia and a sticky substance called mucus. Cilia trap dust particles and germs contained in the air breathed in. Dust particles and germs also stick to mucus, further purifying the air breathed in. There are many blood capillaries in the nostrils which warm the air taken into the nose before it enters the lungs. The nasal tract opens into the pharynx.

Pharynx and larynx

Pharynx is a space common to both respiratory and digestive systems. The larynx starts from the pharynx. The larynx helps to produce our voice.

Lungs

The main organ in the respiratory system is the lung. The lungs are protected by the rib cage. The lungs are made up of millions of sacks filled with air known as alveoli which are covered by a delicate membrane.

Trachea

Think of a tree with two branches. If the trunk is the trachea the two branches are the bronchi. The trunk divides further, finally into twigs with leaves at their ends. The bronchus divides further into branches called bronchioles that open into small sacs called alveoli referred to above.

From the air in the alveoli, oxygen diffuses into the blood through the capillaries. The carbon dioxide in the blood capillaries is released into the alveoli.

In the above activity you would have noticed that the rate of your breathing increased after running around the school ground. The normal rate of breathing is about 20 times per minute. One's breathing rate increases when one is doing exercises or when one gets frightened. That is because the respiratory system supplies extra oxygen required to produce extra energy to cope with such situations.

What should be done to maintain a healthy respiratory system

1. Engage in exercises

It is important to lead an active life to maintain healthy lungs.

2. Stay away from polluted environments

When air polluted with smoke, harmful gases and dust enters the lungs one could fall ill. Therefore it is important to keep your environment, home and bed room clean. When necessary, you can wear masks covering your nose and mouth for protection. One should not breathe through the mouth as the air is cleaned only by the nose. It is your responsibility to stay away from others when you have respiratory diseases and you must not stay near others who have respiratory diseases. You must also contribute as far as possible towards minimizing environmental pollution.

3. Avoid using objects to clean your nose

4. Refrain from smoking and staying near others when they smoke

The main reason for respiratory diseases and cancer is smoking. You become a passive smoker when you are present where people smoke. Develop awareness about health hazards caused by smoking. If your parents smoke, explain the harmful effects of smoking to them.

5. Vaccinations such as BCG should be taken at the right time to avoid tuberculosis and respiratory diseases

Look at the top of your left hand and check whether you have the BCG scar. If you have a long standing cough or loss of weight, get medical advice.

6. Those who have allergic conditions such as asthma or allergic rhinitis should refrain from exposing to allergens

The blood stream transports oxygen and nutrients required to all the organs and cells in the body. It also transports the carbon-dioxide produced in the cells during respiration to the lungs, and all other waste matter to the liver and the kidney. It is the circulatory system that circulates blood in the entire body.

Heart

The main organ of the circulatory system is the heart. It is situated in the rib cage, between the two lungs and slightly to the left. The heart acts like a pump and supplies the necessary power to make the blood flow through the blood vessels. The heart is an organ made up of muscles. As the muscles of the heart don't get exhausted, the circulation of the blood continues throughout the life. There are four chambers in the heart namely the right and left atrium and the right and left ventricles.

Blood vessels

The blood vessels that take the blood away from the heart are called arteries. The blood vessels that bring the blood back from the organs to the heart are called veins. The arteries and veins are connected to each other through the capillaries. The capillaries are like fine fibre and when blood travels through them, substances necessary for the cells are absorbed into the cells and waste matter is released out of the cells into the blood. Other than transportation of substances the blood circulation helps to maintain body temperature.

When we do exercises or get excited our heart beat increases and then the pulse rate also increases. The heart beat of an adult is generally 72 beats a minute.

Blood

When you get a wound you may see blood flowing out of it. There are different types of cells in your blood. The red blood cell is one such type. The blood is red because of the red pigment with iron in it. Red blood cells help to transport both oxygen and carbon dioxide.

The white blood cells fight against germs that enter the body.

When you have bleeding the platelets in the blood help to form blood clots and stop bleeding.

The blood cells not only transport different gases and nutrients, but also transports medicines, hormones and a variety of enzymes.

What you can do to keep the circulatory system healthy

1. Exercise daily

By exercising the heart muscles and all other muscles can be kept healthy. Controlling the body weight will help to maintain a healthy body.

2. Have a balanced diet daily

In lesson 12 you learnt the importance of a nutritional diet and the use of less salt, oil and sugar. Iron rich food improves the transportation of oxygen by the red blood cells. When there is a deficiency of iron, the cells will have less oxygen and you will feel tired.

3. Drink enough water

4. Avoid smoking and be mindful about its ill effects

Smoking can cause heart attacks.

5. Take precautions to avoid diseases such as hookworm disease

As hookworms in your intestines suck your blood, it results in deficiencies of iron and other nutrients. Therefore haemoglobin in the blood decreases. This disease can be avoided by maintaining cleanliness, using footwear and the proper disposal of toilet waste.

6. Be stress free

Stress can cause high blood pressure.

The excretory system is responsible for the removal of wastes produced in the body.

Kidney

The main organ in the excretory system is the kidney. The two kidneys shaped like bean seeds, are placed towards the back of the abdomen on either side of the vertebral column. There are about a million nephrons in each kidney that help to filter the urine. Urine is formed in the nephrons when blood travels through the kidney.

Urinary bladder

The urine produced by the kidneys is taken to the urinary bladder through the ureter and it is stored there. The expandable, muscular walls of the urinary bladder can store the urine. The urine is passed out when the need arises.

Not only the kidneys but also the liver, lungs and the skin help in the excretory process.

How to maintain a healthy excretory system

1. Drink a sufficient amount of clean water

Since a great amount of waste is passed out through urine, it is important to have enough water to make it happen properly. On days where less water is consumed small quantities of dark yellow urine is produced. When, more water is consumed, more light coloured urine is passed.

Reducing the use of chemicals in agriculture and avoiding the release of chemicals into the environment and water, will help us to have clean water. When there is no water sources suitable for consumption, use protection filters to purify water.

2. Pass urine when the need arises

Passing urine when the need arises is important. When urine is stored for a long time it can lead to urinary infections.

3. Keep reproductive organs clean

The organs in the reproductive and excretory systems must be kept clean to avoid diseases. It is better to use underwear made of cotton rather than artificial material such as nylon in a warm country like ours. Change underwear daily and keep them clean.

4. Don't use any medicines without medical advice

5. Minimize the intake of salt

Salt should not be added to the diet of infants from 6 months to one year. You must control the intake of salt right from your childhood.

6. Avoid smoking and the use of alcohol

Smoking and alcohol can cause cancer in the excretory system.

Different organs together form systems. These systems together perform different functions in the body and help to maintain life. These systems act on their own as well as together. In this lesson you learnt about the digestive system, the circulatory system, the respiratory system and the excretory system.

The digestive system digests the food, absorbs the nutrients and passes out the waste matter.

The respiratory system absorbs oxygen into the blood and removes carbon-dioxide formed during this process.

Various substances are transported throughout the body by the circulatory system.

Wastes produced in the body are eliminated from the body by the excretory system.

Various types of diseases can impair the proper functioning of each of these systems. Therefore we must maintain these systems in good health.

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