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Name ________________ Nº___

Surname __________________________

NATURAL SCIENCE

UNIT 1. NUTRITION I

DIGESTIVE SYSTEM & RESPIRATORY SYSTEM

Exam Date: __________________

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UNIT 1. NUTRITION I

DIGESTIVE SYSTEM & RESPIRATORY SYSTEM

In this unit we are going to learn about: 1. What is nutrition?

2. What are the nutrients?

3. Digestive system

3.1.The organs 3.2. The process

4. Respiratory system

4.1. The organs 4.2. The process

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1. NUTRITION

We obtain the energy and the building materials we need to grow from food.

There are four processes involved in nutrition. Each of these processes takes place in a

different system: the digestive system, respiratory, circulatory and excretory system. All

these systems need to work together for proper nutrition to occur.

The four processes involved in nutrition are:

• This is the process of obtaining nutrients from food for our body to use. It is carried out in the digestive system.

DIGESTION

• This is the process of acquiring the oxygen we need to live. It occurs in the respiratory system.

RESPIRATION

• This is the process of transporting nutrients, oxygen and waste products around the body. It occurs in the circulatory system.

CIRCULATION

• This is the process of eliminating waste products produced in our body. It is carried out by the excretory system.

EXCRETION

Nutri tion is a combination of processes which supply our body with the building materials and energy we need to live.

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2. NUTRIENTS Food contains simple substances called nutrients, which provide the building materials

and energy our body needs to grow and work.

Nutrients are classified into groups:

1. CARBOHIDRATES

• Carbohidrates provide fast supply of energy. They are mainly found in pulses, potatoes, cereals and cereal products like bread and pasta.

• FIBRE is a complex carbohidrate that is indigestible for humans. It is necessary to maintain a healthy digestive system, It is found in fruit, vegetables whole grains and cereals.

2. FATS

• Fats provide a slower supply of energy. They are mainly found in oils and butter.

3. PROTEINS • Proteins provide building materials for growth and to repair our body.

They are mainly found in meat, fish, eggs, milk and pulses.

4. VITAMINS AND MINERALS

• Vitamins and minerals are necessary for our body to function properly. They are mainly found in fruit, vegetables and dairy products.

5. WATER

• Water transports other nutrients and waste around the body.

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3. THE DIGESTIVE SYSTEM DIGESTION Digestion is the process of breaking down food into nutrients that our body can use. It

normally takes our body 24 to 48 hours to digest food. Digestion takes place in the

digestive system.

3.1. THE DIGESTIVE SYSTEM: ORGANS The digestive system consists of one long tube, called the digestive tract (also called

digestive tube), and the helper glands.

TEETH Teeth are important for tearing, cutting and grinding food to

prepare it for swallowing and digestion. Children have 20 first (or

milk teeth). From above the age of six, 32 permanent teeth start

to replace their milk teeth.

• The digestive tract is formed by several hollow organs. These organs join together to form a tube from the mouth to the anus. These organs are the mouth, pharynx, oesophagus, stomach, small intestine, large intestine and the anus.

THE DIGESTIVE TRACT

• The helper glands secret substances into the digestive tract. They are the salivary glands (saliva), the liver (bile) and the pancreas (pancreatic juices). These glands produce liquids called the digestive juices.

THE HELPER GLANDS

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3.2. THE PROCESS OF DIGESTION In order to get the nutrients we need from the food we eat, our body first needs to break

down this food. There are four stages in the digestive process:

•  Ingestion begins in the mouth, where our teeth break down food as we chew. The small pieces of food mix with saliva produced by the salivary glands.

• The tongue shapes the food into a ball called a bolus. When we swallow, the bolus is pushed into the pharynx and down the oesophagus, a muscular tube about thirty centimetres long.

1. INGESTION

• Then the bolus reaches the stomach, which produces gastric juices. Muscles in the stomach walls work with gastric juices to break down food even further, forming a thick mixture called chyme.

• The chyme travels to the small intestine, which produces intestinal juices. These juices combine with bile, produced by the liver, and pancreatic juice, produced by the pancreas. The chyme turns into a milky liquid called chyle.

2. DIGESTION

•  In order for the nutrients in chyle to be used by the body, they must pass into the blood. This occurs in the small intestine.

• The inside of the small intestine has thin walls with numerous folds. Each fold has thousands of tiny, finger-like projections called villi. Each villus has numerous capillaries which help to absorb the nutrients into the blood.

3. ABSORPTION OF NUTRIENTS

• After absorption, those parts of food that could not be digested move into the large intestine. In the large intestine, water is absorbed and the remaining undigested food parts turn into solid faeces. Faeces leave the body through the anus.

4. ELIMINATION OF WASTE

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An adult’s digestive

tract is about 9 metres

long in total and food can

take between 24 and 72

hours to make its way from

the mouth to the anus,

depending on the food

and the person.

The small intestine is

packed inside you beneath

your stomach. If you

stretched an adult’s small

intestine it would be about

6,7 metres long- that’s like

22 notebooks lined up end

to end in a row!!!

How long is the large

intestine?

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WHAT HAPPENS WHEN WE SWALLOW?

THE EPIGLOTTIS The epiglottis is a flap of cartilage located

behind the tongue, at the top of the larynx. It

prevents the food from going down the windpipe

and into the lungs. It flops down over the

windpipe when you shallow to keep food from

going into your lungs. Without your epiglottis,

you would cough or choke every time you eat.

PERISTALTIC MOVEMENTS The muscles in the wall of the oesophagus slowly

squeeze the food down to the stomach. It’s wave-like

successive muscular contractions. The smooth muscle

of the oesophagus contracts and relaxes in sequence,

and this pushes the ball of food down the oesophagus.

This works in one direction only, and also works in the

lower regions of the digestive system.

DIGESTION AND HEALTH In order to look after our digestive system, we need to have a healthy diet.

Diet refers to all the foods that a person regularly eats. A complete balanced

diet means eating the right amount of food from each of the food groups.

• A diet is complete when it includes all of the types of nutrients.

• A diet is balanced when it has the correct amount of each nutrient.

When a diet is not complete or balanced, we can develop disorders or diseases.

For example, if a diet is too rich in carbohydrates and fats, energy intake is too

high. When this happens, the body stores extra energy as fat. This causes

obesity and other health problems.

On the contrary, when a diet is missing nutrients, we have little energy. This

slows down growth and development and also leads to disease.

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4. THE RESPIRATORY SYSTEM RESPIRATION Respiration is the process by which we breathe in or inhale, to obtain the oxygen our

body needs, and we breathe out, or exhale, to expel the carbon dioxide our body

produces. Respiration is carried out by the respiratory system.

4.1. THE RESPIRATORY SYSTEM:ORGANS The respiratory system consists of the respiratory tract or (air passageways) and the

lungs.

• The respiratory tract are the tubes through which air goes in and out of our bodies. They connect the lungs with the outside of the body. They include the nasal cavity (nostrils), pharynx, larynx, trachea, bronchi and bronchioles.

THE RESPIRATORY TRACT

• The lungs are two spongy organs where the gas exchange takes place. Each of our lungs is made up of millions of alveoli (about 600 million!).

• They are in the thoracic cavity, which is formed by the sternum, the ribs and the spinal column. They are separated from the stomach by a muscle called the diaphragm.

THE LUNGS

The LEFT lung is

smaller than the right

one…why??

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4.2. THE PROCESS OF RESPIRATION Breathing movements, inhalation and exhalation, are carried out by the diaphragm and

the intercostal muscles.

• During inhalation, the lungs and the thoracic cavity expand. The diaphragm, a strong muscle below the lungs, contracts and goes down. The muscles between the ribs, which are called intercostal muscles, push the ribcage up and out. The space inside the thoracic cavity increases, so air comes in. Then the lungs inflate.

• When we inhale, air enters through the nose (nostrils) and mouth. The hairs inside the nose trap dust particles and cleans the air.

• The air passes through the pharynx, then travels down to the larynx and the trachea. The trachea is divided into two branches called bronchi. The bronchi take the air to each lung.

• Inside the lungs, the bronchi are divided into smaller branches called bronchioles. The bronchioles lead to the alveoli or air sacs. Alveoli are moist surfaces covered in

blood vessels (capillaries) in the lungs where GAS EXCHANGE takes place: oxygen in the air is absorbed into the blood and carbon dioxide passes from the blood to the alveoli.

1. INHALATION

• During exhalation, the lungs and the thoracic cavity contract. The diphragm relaxes and goes up. The ribcage goes down and in. The space inside the chest cavity (ribcage) decreases, so air is pushed out. Then the lungs deflate.

• This pushes the air that contains carbon dioxide out of our body. It goes through the bronchioles to the bronchi and the trachea. Then to the larynx, then the pharynx and finally out through the mouth and nose.

2. EXHALATION

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GAS EXCHANGE The alveoli in the lungs are surrounded by tiny blood vessels. Both the alveoli and the

blood vessels have very thin walls. This allows oxygen and carbon dioxide to pass

between the lungs and the blood.

• The oxygen in the air we inhale

passes from the air sacs into the

blood. The blood carries the oxygen

to all the cells in our body.

• The carbon dioxide produced by all

the body cells travels through the

blood and passes into the air sacs.

The air sacs expel the carbon dioxide

when we exhale.

WHY DO WE NEED OXYGEN?

CELLULAR RESPIRATION

All animals need oxygen to burn up food and

produce energy in their bodies.

Nutrients and oxygen enter the cell and

combine to produce the energy the cell needs.

This process is called cellular respiration.

During this process, carbon dioxide is produced,

which must be expelled from our bodies.

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THE VOCAL CORDS The vocal cords are two very thin bands of

muscle inside of the larynx. When we breathe

in, the vocal cords open to let the air pass

through the larynx, into the trachea and down to

the lungs. When we breathe out and want to

talk, the vocal cords close. The air causes the

vocal cords to vibrate, which makes sound. Hum a

little bit of your favourite song and touch you larynx. Can you feel vibrations?

RESPIRATION AND HEALTH To keep your respiratory system healthy you

should:

• Exercise regularly.

• Eat a diet that is high in

vitamins and minerals

• Drink water regularly.

• Wash your hands regularly.

• Do not smoke.

• Avoid places with high levels

of air pollution, especially

when exercising.

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REFERENCES

BOOKS - Science The world around us 6 Primary Education. Anaya English, 2013

- Science The world around us 5 Primary Education. Anaya English, 2013

- Top Science 5 Primary. Ed Santillana/ Richmond, 2011

- Top Science 6 Primary. Ed Santillana/ Richmond, 2011

- Natural and Social Science Primary 5 Pupil’s book Macmillan, 2012.

- Social and Natural Sciences 5 Look and Think Oxford Education, 2010

- Science 5 Primary, sm, 2009

- Natural Science. Primary 5 Anaya English- ANAYA, 2014

- Natural Science. Primary 6 Anaya English- ANAYA, 2015

- Science “My World” Primary 6, Edelvives, 2013.

- Natural Science 6. Santillana.

- Natural Science Primary 6 ByME Macmillan Edelvives, 2015.

- Natural Science 5 Primary Student’s book. edebé, 2015.

- Natural Sciences Think, Do, Learn. OUP, 2014.

WEBS

• https://www.ducksters.com/science/digestive_system.php

• https://www.ducksters.com/science/breathing.php

• https://kidshealth.org/en/kids/digestive-system.html?WT.ac=en-k-slpmsh-k-lt#catchanging-body

• http://sciencewithme.com/digestive-system-for-kids/

• https://kidsbiology.com/human-biology/digestive-system/

• http://www.sciencekids.co.nz/sciencefacts/humanbody/digestivesystem.html

• https://www.dkfindout.com/us/human-body/digestion/

• https://www.dkfindout.com/us/human-body/lungs-and-breathing/

• http://mocomi.com/cellular-respiration/

• http://mocomi.com/how-does-the-digestive-system-work/

• http://mocomi.com/how-does-the-respiratory-system-work/

• https://thekidshouldseethis.com/post/22254893339

• https://kidshealth.org/en/kids/word-epiglottis.html#catchanging-body

• https://kidshealth.org/en/kids/digestive-system.html#catchanging-body

• https://kids.kiddle.co/Peristalsis

• http://encyclopedia.kids.net.au/page/pe/Peristalsis

• https://study.com/academy/lesson/the-human-voice-lesson-for-kids.html