Body systems. Attnom Academy

S3.3.1 Chapter 1

Organs and systems

What is inside my body, and how do all the parts work together?

Your guess

Pick one before you read on. It is fine to be wrong.

Your guess

A Each organ does its job alone. It needs no help from the others.
You picked A. Read on. At the end, the chapter comes back to your guess.
B Organs work in teams, and the teams need each other.
You picked B. Read on. At the end, the chapter comes back to your guess.
C Only the brain works. The other parts just fill the space.
You picked C. Read on. At the end, the chapter comes back to your guess.

By the end you can

Name the main organ systems and one organ in each
Explain how two systems work together when you run

Your body is not one lump. It is made of parts, and each part has its own job. Build the picture below one step at a time.

Draw it first

Draw the inside of the body

1 Draw the head, the arms, the trunk and the tops of the legs. Leave the inside empty.
2 Put in the two lungs. Put the heart between them, a little to the left of the middle.
3 Add the liver on the right, the stomach on the left, and the intestines below.
4 Add the brain in the head, the two kidneys and the bladder.

The body in the picture faces you. So its left side is on the right of the page. Its right side is on the left.

An organ is a part of the body with one main job. The heart is an organ. So are the lungs, the stomach and the brain.

Organs work in teams. A team of organs that does a big job together is an organ system.

The digestive system breaks food down. The stomach and the intestines are part of it.

The lungs belong to the breathing system, which takes in air. The heart belongs to the circulatory system, which moves blood.

The brain is in the nervous system, which sends signals. The kidneys and the bladder are in the excretory system, which removes waste liquid. The kidneys lie at the back, one each side of the spine.

Two more systems are not in the picture. One is the reproductive system, for making new life. You can read about it in the book Growing up. The other is the skeleton and the muscles, below.

The skeleton and the muscles make the skeletal and muscular system. It holds you up and moves you. The skull guards the brain. The ribs guard the heart and lungs.

See it three ways

With things

If you are well, run on the spot for one minute. Your chest moves faster and your heart beats faster. Your muscles feel warm.

As a picture

In words

The lungs take oxygen from the air. The heart pushes the blood round the body. The blood carries the oxygen to the muscles. Three systems work as one team.

Try it

Feel your body at work

You need: your own body, a quiet place to sit.

Be safe: Stop at once if you feel dizzy or have any pain. If you have a heart or breathing illness, ask a health worker before you run.

Sit still. Put one hand flat on your chest, a little to the left of the middle. Feel the beat of your heart.
Breathe in slowly. Feel your ribs move up and out under your hand.
If you are well, jog on the spot for 30 seconds. Then feel your chest again.

What you will see: After jogging your heart beats faster and you breathe faster. Two systems speed up together.

If you cannot try it, this is what happens.

A wrong idea many people have

Each organ does its job alone.

Why it feels right: Every organ has its own name, its own place and its own job.

The test that breaks it: Think of running. The muscles need oxygen from the lungs. The heart must carry it there. If any one of them stopped, the runner would have to stop.

What is true: Organs work in teams called systems, and the systems need each other.

Key words

organ: a part of the body with one main job, such as the heart or the lungs.
organ system: a team of organs that does a big job together.

Back to your guess

The answer is B: Organs work in teams, and the teams need each other.

Organs work in teams called systems. When you run, your lungs, heart and muscles all work together, so no part works alone.

Keep it

Copy this into your exercise book.

An organ has one main job. A team of organs is an organ system. Systems need each other. Running uses the lungs, the heart and the muscles together.

Draw: Draw a standing person. Put in the lungs, the heart, the stomach and the brain, and label each one.

S3.3.2 Chapter 2

Digestion

What happens to food after I swallow it?

Your guess

Pick one before you read on. It is fine to be wrong.

Your guess

A It stays in the stomach until the body has used all of it.
You picked A. Read on. At the end, the chapter comes back to your guess.
B It travels through a long tube and is broken into tiny pieces on the way.
You picked B. Read on. At the end, the chapter comes back to your guess.
C It goes straight into the blood, just as it is.
You picked C. Read on. At the end, the chapter comes back to your guess.
D It turns into waste in the stomach, and the body takes nothing from it.
You picked D. Read on. At the end, the chapter comes back to your guess.

By the end you can

Trace food through the mouth, gullet, stomach and intestines
Explain why food must be broken into small pieces to be absorbed

Think of a meal of rice and beans. You chew it, swallow it, and feel nothing more. But your body works on it for many hours. Draw its path first.

Draw it first

Draw the path of food

1 Draw the mouth. Food goes in here.
2 Draw the gullet, a tube that leads down from the mouth to the stomach.
3 Draw the stomach, a bag where food is mixed and squeezed.
4 Draw the small intestine, a long tube in many coils.
5 Draw the large intestine round the coils. Waste leaves at the end.

Digestion is breaking food down into tiny pieces. The long tube that food goes through is called the gut. It starts at the mouth and ends where waste leaves the body.

In the mouth, your teeth cut and grind food. Saliva makes it wet and starts to break it down.

Incisors cut, canines tear and molars grind. Teeth break food into smaller pieces. This is the first step of digestion.

Next you swallow. Food goes down the gullet. Its muscles squeeze, in waves, and push the food along. That is why you can swallow even when you lie down.

The stomach is a stretchy bag. Its muscles squeeze the food and mix it with juices. The food turns into a thick liquid.

The small intestine is a very long, coiled tube. More juices break the food into the tiniest pieces here. These tiny pieces pass through the wall of the small intestine into the blood. We say the blood absorbs them.

This is a model. In it, the gaps are wider than the small pieces and narrower than the big ones. Only small pieces get through.

What is left goes into the large intestine. It takes back water. The rest leaves your body as waste.

Each part of the gut has one job.

See it three ways

With things

Pour rice grains and sugar water through a cloth into a cup. The sugar water goes through. The rice stays on top.

As a picture

In words

A cloth is a model of the gut wall. Only tiny pieces can pass through a cloth with tiny gaps. So food must be broken into tiny pieces before the blood can take it in.

Try it

A cloth for a gut wall

You need: a clean cloth, two cups, a spoon of rice, a spoon of sugar, water.

Be safe: Do not eat or drink the rice, the sugar water or anything from the cloth. Wash your hands afterwards.

Stir the sugar into half a cup of water until it has gone clear.
Hold the cloth tight over the empty cup. Pour the sugar water on to it. Watch what goes through.
Now pour the rice on to the cloth. Watch what happens.

What you will see: The sugar water goes through the cloth. The rice grains stay on top.

If you cannot try it, this is what happens.

A wrong idea many people have

Digestion happens only in the stomach.

Why it feels right: The stomach is big, and you can feel it fill when you eat.

The test that breaks it: Follow the picture of the gut. Food is chewed in the mouth and mixed in the stomach. Most of it is absorbed in the small intestine, which is longer than the rest.

What is true: Digestion starts in the mouth and goes on all along the gut. Most absorbing is done in the small intestine.

Key words

digestion: breaking food down into tiny pieces.
gullet: the tube that takes food from the mouth to the stomach.
small intestine: a long coiled tube where the tiny pieces pass into the blood.
absorb: to take in. The blood absorbs tiny pieces of food through the gut wall.
large intestine: the wide tube that takes back water and leaves the waste.

Back to your guess

The answer is B: It travels through a long tube and is broken into tiny pieces on the way.

Food travels through a long tube called the gut. On the way it is broken into tiny pieces, and the body takes in the useful ones.

Keep it

Copy this into your exercise book.

Food goes mouth, gullet, stomach, small intestine, large intestine. It is broken into tiny pieces. Only tiny pieces pass through the gut wall into the blood.

Draw: Draw the gut as one long tube. Label the five parts and draw an arrow the way the food goes.

S3.3.3 Chapter 3

Nutrients and diet

Why do I need different kinds of food, and what happens if I miss one?

Your guess

Pick one before you read on. It is fine to be wrong.

Your guess

A All food does the same job, so any food will do.
You picked A. Read on. At the end, the chapter comes back to your guess.
B Each kind of food does its own job, so the body needs a mix.
You picked B. Read on. At the end, the chapter comes back to your guess.
C Only meat and sweet food are good for the body.
You picked C. Read on. At the end, the chapter comes back to your guess.

By the end you can

Explain what carbohydrates, proteins, fats, vitamins, minerals and fibre do
Name a disease caused by too little of a vitamin or mineral

Food is more than something that fills your belly. It holds nutrients, the parts of food that your body uses. Build the picture of what each one does.

Draw it first

Draw what each nutrient does

1 Write three nutrients, and one job for each: carbohydrate, protein and fat.
2 Add vitamins and minerals. They keep your body working.
3 Add fibre, and water too. Your body needs both.

Carbohydrates give you energy. Rice, bread, maize and cassava are full of them. Your muscles and brain use this energy all day.

Proteins build your body and mend it when it is hurt. Beans, fish, eggs, nuts and meat have a lot of protein.

Fats and oils store energy and keep you warm. A little fat gives a lot of energy, so you need only a small amount.

Vitamins and minerals are needed in tiny amounts. They help the body use everything else. Vitamins and minerals give no energy themselves.

Fibre is the part of plants that your body cannot digest. It helps food move through the gut. Vegetables, fruit and whole grains have fibre.

Most foods hold more than one nutrient. This table names the one each food is best known for.

Iron helps the blood carry oxygen. Your skin makes vitamin D when sunlight falls on it. Iodine is used by the thyroid, a gland in the neck. With too little iodine the thyroid grows bigger, and the neck swells.

Too little of a vitamin or a mineral, for a long time, can make a person ill. This is a deficiency disease.

Each of these diseases has a cause you can name.

Scurvy makes the gums sore and bleed, and cuts heal slowly. Rickets makes the bones of a child soft, so the legs can bend.

Leg bones hold your weight. They need vitamin D and calcium to grow hard. Without them the bones stay soft and can bend.

Anaemia makes a person pale and tired, because the blood carries too little oxygen. Goitre makes the neck swell.

A mixed diet helps to prevent them. Sunlight on the skin gives vitamin D. Where food has too little iodine, salt with iodine added prevents goitre. Anaemia has other causes too. A health worker can test and advise.

See it three ways

With things

Write down everything you ate yesterday. Put each food under energy or growth. Some foods belong in both.

As a picture

In words

Carbohydrates and fats give energy. Proteins help you grow and mend. Peas, milk and eggs hold both kinds, so they sit in the middle.

Try it

Find the fat

You need: 3 pieces of plain paper, a few drops of cooking oil, water, a slice of raw potato.

Be safe: Do not eat the potato or taste the oil. Wash your hands after you have touched them.

Put a drop of oil on one piece of paper. Put a drop of water on the second. Rub the cut face of the potato on the third.
Leave all three for an hour in a warm place. Hold each one up to the light.
Look for a mark that lets the light through and does not go away.

What you will see: The oil leaves a clear greasy mark. The water dries away. The potato leaves a damp mark that dries away. Fat leaves a clear mark that stays.

If you cannot try it, this is what happens.

A wrong idea many people have

Vitamins give you energy.

Why it feels right: People who feel tired are often told to take vitamins.

The test that breaks it: Energy comes from carbohydrates and fats. A person who eats vitamins but no rice, bread or oil would still run out of energy.

What is true: Carbohydrates and fats give energy. Vitamins and minerals help your body work, and they give no energy.

Key words

nutrients: the parts of food that the body uses.
carbohydrates: nutrients that give energy, such as the starch in rice and bread.
proteins: nutrients that build the body and mend it.
vitamins: nutrients needed in tiny amounts to keep the body working.
minerals: nutrients such as iron and calcium, needed in small amounts.
fibre: the part of plants that helps food move through the gut.

Back to your guess

The answer is B: Each kind of food does its own job, so the body needs a mix.

Each nutrient has its own job. The body needs a mix of them, and too little of one can make a person ill.

Keep it

Copy this into your exercise book.

Carbohydrates and fats give energy. Proteins build and mend. Vitamins and minerals help the body work. Fibre moves food on. Too little iron, iodine or a vitamin can cause disease.

Draw: Draw a table of six nutrients, with one job and one food beside each.

S3.3.4 Chapter 4

Breathing

How does air get into my chest when I breathe in?

Your guess

Pick one before you read on. It is fine to be wrong.

Your guess

A The lungs are muscles. They pull the air in by themselves.
You picked A. Read on. At the end, the chapter comes back to your guess.
B The ribs and a sheet of muscle make the chest bigger, so air flows in.
You picked B. Read on. At the end, the chapter comes back to your guess.
C The nose and mouth push the air in.
You picked C. Read on. At the end, the chapter comes back to your guess.

By the end you can

Make a model lung with a plastic bottle and a bag
Explain how the ribs and diaphragm move air in and out

You breathe all day and all night, and you hardly think about it. How does the air get in? A model will show you. Build it up one step at a time.

Draw it first

Draw the model lung

1 Draw a bottle with no bottom. Hang a balloon inside it on a straw. Stretch a sheet across the open end.
2 Now pull the sheet down. The room inside gets bigger, and the balloon fills with air.

In the model, the bottle stands for your chest. The balloon is a lung, the straw is the windpipe, and the sheet is the diaphragm.

Pull the sheet down and the room inside gets bigger. The air in the bottle, round the balloon, is spread thinner, so it squeezes the balloon less. Air from outside squeezes more, so it pushes in through the straw and blows the balloon up.

Push the sheet up and the room gets smaller. The air is squeezed, and it flows out through the straw.

Your chest works the same way. The lungs are two soft bags full of tiny air spaces. They have no muscles that move them. They are filled and emptied by the movement of the chest around them.

Breathing out. The diaphragm domes up. The ribs move down and in. The chest gets smaller.

Breathing in. The diaphragm tightens, flattens and moves down. The ribs move up and out. The chest gets bigger.

The diaphragm is a sheet of muscle under the lungs. When you breathe in, it tightens, flattens and moves down. The muscles between your ribs lift them up and out.

The chest gets bigger, so the air inside the lungs is squeezed less. Its pressure falls, and air from outside flows in. When you breathe out, these muscles relax. The diaphragm goes back up into a dome, and the ribs drop. The chest gets smaller and air flows out.

The ribs make a strong cage round the lungs. They can still move a little, so the chest can grow bigger.

See it three ways

With things

Put your hands on the sides of your ribs. Breathe in slowly. Feel your ribs move out. Breathe out and feel them go back.

As a picture

In words

Air goes in through the nose or mouth. It goes down the windpipe and into the lungs. It comes out the same way. This is breathing in and breathing out.

Try it

Make a model lung

You need: a clear plastic bottle, a balloon, a straw or a short tube, a strong plastic bag, string and tape, a grown up to cut the bottle.

Be safe: A grown up must cut the bottle, because the cut edge is sharp. Cover it with tape. Never put the straw or the balloon in your mouth. Keep balloons and bags away from small children.

A grown up cuts the bottom off the bottle. Cover the cut edge with tape.
Push the straw into the neck of the balloon. Tie it tight with string.
Push the straw through the neck of the bottle, so the balloon hangs inside. Seal the neck with tape, so air can only move through the straw.
Tape the plastic bag over the open end of the bottle, a little loose. Tape a small tab to the middle of the bag, to pull it by.
Pull the tab down, gently. Then push the bag up, gently. Watch the balloon each time.

What you will see: When you pull the bag down, the balloon fills. When you push the bag up, the air comes out of the balloon.

If you cannot try it, this is what happens.

A wrong idea many people have

The lungs are muscles that pull air in.

Why it feels right: Your chest moves when you breathe, and the lungs are inside it.

The test that breaks it: In the model, nothing pulls on the balloon. It fills only because the room around it grows. Your lungs work the same way.

What is true: The lungs have no muscles that move them. The diaphragm and the rib muscles change the size of the chest. Then air flows in or out.

Key words

lungs: the two soft bags in the chest that fill with air.
windpipe: the tube that takes air from the nose and mouth to the lungs.
ribs: the curved bones that make a cage round the lungs.
diaphragm: the sheet of muscle under the lungs.
breathing in: taking air into the lungs. The chest gets bigger.
breathing out: pushing air out of the lungs. The chest gets smaller.

Back to your guess

The answer is B: The ribs and a sheet of muscle make the chest bigger, so air flows in.

The lungs have no muscles. A sheet of muscle called the diaphragm and the ribs make the chest bigger. Then air flows in.

Keep it

Copy this into your exercise book.

The lungs have no muscles. Breathing in, the diaphragm moves down and the ribs move up and out. The chest gets bigger and air flows in. Breathing out is the reverse.

Draw: Draw the bottle model with the sheet pulled down. Label the straw, the balloon, the bottle and the sheet.

S3.3.5 Chapter 5

Gas exchange in the lungs

How does the oxygen in the air get into my blood?

Your guess

Pick one before you read on. It is fine to be wrong.

Your guess

A The air goes straight into the blood, and the blood carries it round.
You picked A. Read on. At the end, the chapter comes back to your guess.
B Oxygen passes through the very thin walls of tiny air sacs into the blood.
You picked B. Read on. At the end, the chapter comes back to your guess.
C The heart takes the oxygen out of the air.
You picked C. Read on. At the end, the chapter comes back to your guess.

By the end you can

Explain how oxygen enters the blood and carbon dioxide leaves it
Explain how smoke from tobacco and cooking fires harms the lungs

Breathing brings air into your chest. But the air is not the part your blood needs. It needs one gas in the air. Draw the place where it passes in.

Draw it first

Draw an air sac and a capillary

1 Draw a tiny air sac with a very thin wall. Draw a capillary, a narrow tube of blood, right against it.
2 Draw an arrow for oxygen into the blood, and an arrow for carbon dioxide out of the blood.

Your lungs hold millions of tiny air sacs. Each one is like a very small balloon, wrapped in a net of capillaries. A capillary is a blood tube so thin that blood cells pass through it in single file.

The windpipe splits into smaller and smaller tubes. Each ends in a cluster of air sacs.

The wall of an air sac and the wall of a capillary are both very thin. The blood is very close to the air.

The blood that comes to the lungs has used up some of its oxygen. It holds a lot of carbon dioxide, a waste gas. The air in the sacs has plenty of oxygen and little carbon dioxide.

Gases spread from where there is more of them to where there is less. So oxygen passes from the air sac into the blood. Carbon dioxide passes from the blood into the air sac. This swap is gas exchange. You breathe the carbon dioxide out.

Air holds about 21 parts in 100 of oxygen. Breathed-out air has less oxygen and more carbon dioxide. It still holds about 16 parts in 100 of oxygen.

See it three ways

With things

Put a hand on your chest and breathe in deeply. The air goes towards your air sacs. The blood then carries its oxygen to every cell, even in your fingers.

As a picture

In words

Oxygen passes from an air sac into the blood. The blood carries it to every cell. Carbon dioxide makes the trip the other way.

Why does the body want oxygen? Every cell uses it. In respiration, a cell uses oxygen to release energy from sugar. It makes carbon dioxide and water as waste.

In words: sugar + oxygen → carbon dioxide + water, and energy is released. Respiration happens in every cell. Breathing is only how the air gets in and out.

Breathing and respiration are two different things.

Smoke harms the lungs. Tobacco smoke holds a sticky tar, poisons, and a drug called nicotine that is hard to give up. It damages the lining of the tubes. It breaks down the walls between air sacs. Then there are fewer, bigger sacs with less surface, so less oxygen can pass in. It also holds a gas that takes the place of oxygen in the blood. Then the blood carries less. It harms people who breathe it near a smoker.

Smoke from a cooking fire indoors harms the lungs too. Wood, charcoal or dung can all give smoke that causes coughing and lung disease. Children and the person who cooks are at most risk. Never burn charcoal in a closed room, even when you see no smoke. It makes a poison gas that you cannot see or smell.

Many small sacs give a large surface. After smoke damage there are fewer, bigger sacs, so less oxygen can pass into the blood.

A window, a door or a chimney lets the smoke out. Keep small children away from the smoke. Never burn charcoal in a closed room. A health worker can advise.

Try it

Mist from your breath

You need: 2 spoons, a cup of cold water, a dry cloth.

Be safe: Use only cold water from the tap or a jar. Do not blow on anything hot. Do not put a spoon in your mouth.

Put both spoons in the cold water for one minute. Dry them with the cloth.
Hold one cold spoon close to your mouth. Breathe out slowly on to it.
Hold the other cold spoon the same way, in the room air, for the same time. Do not breathe on it.

What you will see: A thick mist forms on the spoon you breathed on. The other spoon stays clear, or mists only a little. Breath is warm and carries much water.

If you cannot try it, this is what happens.

A wrong idea many people have

We breathe in oxygen and breathe out only carbon dioxide.

Why it feels right: People say that oxygen goes in and carbon dioxide comes out.

The test that breaks it: The air sacs take only some of the oxygen from each breath. The rest is breathed out again.

What is true: Breathed-out air has less oxygen and more carbon dioxide than breathed-in air. It still holds some oxygen.

Key words

air sacs: the tiny bags at the ends of the lung tubes. Gases pass in and out of the blood here.
capillaries: the thinnest blood tubes. They wrap round the air sacs.
gas exchange: oxygen passing into the blood while carbon dioxide passes out.
respiration: what every cell does to release energy from sugar, using oxygen.

Back to your guess

The answer is B: Oxygen passes through the very thin walls of tiny air sacs into the blood.

The lungs hold millions of tiny air sacs. Oxygen passes through their thin walls into the blood, and carbon dioxide passes the other way.

Keep it

Copy this into your exercise book.

Oxygen passes from the air sacs into the blood. Carbon dioxide passes out. Respiration happens in every cell. Smoke harms the lungs.

Draw: Draw one air sac with a blood tube beside it. Add an arrow for oxygen in and an arrow for carbon dioxide out.

S3.3.6 Chapter 6

The heart and blood

Where does my blood go, and what does it carry?

Your guess

Pick one before you read on. It is fine to be wrong.

Your guess

A Blood goes from the heart to the body, and then it is used up.
You picked A. Read on. At the end, the chapter comes back to your guess.
B Blood goes round and round in a loop, past the lungs and the body.
You picked B. Read on. At the end, the chapter comes back to your guess.
C Blood goes to the lungs and stays there until you breathe out.
You picked C. Read on. At the end, the chapter comes back to your guess.

By the end you can

Trace the path of blood through the heart, lungs and body
Name what blood carries, such as oxygen, food and waste

Put a hand on your chest. The beat you feel is your heart. The heart is a strong muscle that pushes blood round your body, all day and all night. Draw the loop first.

Draw it first

Draw the loop of blood

1 Draw three boxes: the body, the heart in two halves, and the lungs. Add an arrow from the body to the right side of the heart.
2 The right side pumps the blood to the lungs. Add that arrow.
3 In the lungs the blood takes up oxygen. It goes to the left side of the heart.
4 The left side pumps it round the body. This closes the loop.

The picture is a plan, not a map of the real heart. It shows the order. The right side of the heart is on the left of the page, because the body faces you.

Dashed arrows are blood with less oxygen. Solid arrows are blood with more oxygen. The blood goes through the heart twice on each trip round the body.

The heart sits between the lungs, a little to the left of the middle. It is about as big as your fist.

The heart is made of muscle. Each time it squeezes, it pushes blood along. One beat is one squeeze. The two sides squeeze together.

Blood moves in tubes called blood vessels. Arteries carry blood away from the heart. Veins bring blood back to it. Capillaries are the tiny tubes between them. Gases and food pass in and out through their thin walls.

See it three ways

With things

Put two fingers on your wrist, below the thumb. Press gently. The beat you feel is the push of the blood along an artery.

As a picture

In words

Blood leaves the heart in arteries. It passes through capillaries. It returns to the heart in veins. Each push of the heart is felt as a pulse.

Blood is a delivery service. It picks up from one place and drops off in another.

Blood picks up oxygen in the lungs. It picks up nutrients from the small intestine. It collects waste from the cells and drops it at the lungs and the kidneys.

Blood has a liquid part, called plasma, and cells in it. Plasma also carries waste.

Try it

Feel your pulse

You need: your own hand and wrist, a quiet place to sit.

Be safe: Press gently. Never press hard on your neck.

Sit still for a minute. Turn one hand palm up.
Lay two fingers of the other hand on the wrist, in line with the thumb. Do not use your thumb, because it has a pulse of its own.
Press gently until you feel a small beat. Then put your hand flat on your chest and feel the beat there.

What you will see: You feel a beat at your wrist and a beat in your chest. They keep time, because each beat of the heart pushes blood along your arteries.

If you cannot try it, this is what happens.

A wrong idea many people have

Blood is blue inside the body until air touches it.

Why it feels right: Veins look blue under the skin, and some pictures draw them blue.

The test that breaks it: At a clinic, a health worker takes blood from a vein straight into a closed tube. The blood in the tube is dark red, and no air has touched it.

What is true: Blood is always red. It is bright red with more oxygen and a darker red with less. The skin makes veins look blue.

Key words

blood vessels: the tubes that blood moves in.
arteries: blood vessels that carry blood away from the heart.
veins: blood vessels that bring blood back to the heart.
capillaries: the tiniest blood vessels, where gases and food pass in and out.

Back to your guess

The answer is B: Blood goes round and round in a loop, past the lungs and the body.

Blood goes round and round in a loop. It passes through the heart, then the lungs, then the heart again, then the body.

Keep it

Copy this into your exercise book.

Blood goes body, heart, lungs, heart, body. Arteries carry it away from the heart and veins bring it back. Blood carries oxygen, food and waste. Blood is always red.

Draw: Draw the loop of blood: body, right side, lungs, left side, with arrows. Show less oxygen with dashes.

S3.3.7 Chapter 7

Pulse, breathing and exercise

Why do my heart and my breathing speed up when I run?

Your guess

Pick one before you read on. It is fine to be wrong.

Your guess

A The heart beats faster, but my breathing stays the same.
You picked A. Read on. At the end, the chapter comes back to your guess.
B Both speed up, because my muscles need more oxygen.
You picked B. Read on. At the end, the chapter comes back to your guess.
C Both speed up only because I feel afraid.
You picked C. Read on. At the end, the chapter comes back to your guess.
D My lungs have run out of air, so I must gasp.
You picked D. Read on. At the end, the chapter comes back to your guess.

By the end you can

Measure pulse and breathing rate before and after exercise
Show the results in a table and a bar chart
Explain why both rates rise during exercise

Your body keeps count of its own work. The pulse is how many times your heart beats in one minute. The breathing rate is how many breaths you take in one minute. Here are the results of one test. Draw them first.

Draw it first

Draw the results of the test

1 Write the two pulse counts in a table, with the unit, beats per minute, at the top.
2 Draw a bar for each count. The taller bar is the faster pulse.

Amina sat still, then counted the beats at her wrist for 15 seconds. She ran on the spot for one minute and counted again, at once. A bar chart shows the same numbers as bars. The taller bar is the larger number.

A minute is four lots of 15 seconds. So a count in 15 seconds, times 4, gives beats per minute.

See it three ways

With things

Find your pulse at the wrist. Count the beats for 15 seconds. Multiply the count by 4.

As a picture

In words

There are four lots of 15 seconds in one minute. So the count in 15 seconds, times 4, is the pulse for a whole minute.

In symbols

18 × 4 = 72

Worked example

Amina counts 18 beats in 15 seconds at rest. What is her pulse in beats per minute?

A minute is four lots of 15 seconds.
So multiply the count by 4.
18 × 4 = 72.

Answer: 72 beats per minute

Breathing is counted the same way. One breath is one breath in and one breath out. Kofi counted his breaths for 30 seconds and multiplied by 2.

Kofi took more breaths each minute after his run.

Everyone is different. A resting pulse is not the same for every person, and there is no one right number. The best test is you against you: compare your own pulse at rest and after exercise.

Both rates went up. Here is why. Working muscles use oxygen faster and make more carbon dioxide. The blood must carry oxygen to them quickly, so the heart beats faster. The lungs must take in more air and clear the carbon dioxide, so you breathe faster. The heart does not make you breathe faster. Both answer the same need.

The muscles need more oxygen, so the heart and the lungs both speed up. Neither one speeds up the other.

After you rest, both rates slow down again. A fair test counts for the same time each time. It starts when you have been still for a few minutes.

Try it

Test your pulse and breathing

You need: a clock or a watch with a second hand, paper and a pencil, a quiet place to sit.

Be safe: Exercise only if you feel well. Stop at once if you feel dizzy or have pain. If you have a heart or breathing illness, ask a health worker first.

Sit still for a few minutes. Count your pulse for 15 seconds, then count your breaths for 30 seconds. A friend can count your breaths for you. Write both numbers down.
If you are well, jog on the spot for one minute. Then sit down and count again at once.
Multiply the pulse count by 4 and the breath count by 2. Draw a table and a bar chart of your own results.

What you will see: Your pulse and your breathing are both higher straight after you run. They slow down again as you rest.

If you cannot try it, this is what happens.

A wrong idea many people have

Everyone has the same resting pulse, and there is one right number.

Why it feels right: A book or a chart often gives just one number.

The test that breaks it: Ask a few people to count their pulse at rest. Each count may differ, and all of them may be well.

What is true: A resting pulse differs from person to person. Compare your own pulse at rest and after exercise.

Key words

pulse: the number of times your heart beats in one minute, felt as a beat at the wrist.
breathing rate: the number of breaths you take in one minute.
beats per minute: the unit of pulse. A count in 15 seconds, times 4, gives it.
bar chart: a chart where the height of each bar shows an amount.

Back to your guess

The answer is B: Both speed up, because my muscles need more oxygen.

Both speed up because working muscles use oxygen faster. The heart sends more blood and the lungs take in more air.

Keep it

Copy this into your exercise book.

Pulse is beats per minute. Count for 15 seconds and multiply by 4. Both pulse and breathing rise in exercise, because muscles need more oxygen.

Draw: Draw a table of your pulse at rest and after a run. Then draw a bar chart of it.

S3.3.8 Chapter 8

Drugs, alcohol and health

What do tobacco, alcohol and medicines do to my body?

Your guess

Pick one before you read on. It is fine to be wrong.

Your guess

A Anything a doctor gives you is safe, in any amount.
You picked A. Read on. At the end, the chapter comes back to your guess.
B A medicine helps only in the right amount. Too much can harm.
You picked B. Read on. At the end, the chapter comes back to your guess.
C Tobacco and alcohol only harm the person who uses them.
You picked C. Read on. At the end, the chapter comes back to your guess.

By the end you can

Explain how tobacco, alcohol and other drugs harm body systems
Explain why medicines must be taken only as directed

A drug is anything, other than food, that changes the way your body works. Some drugs are medicines. Others are tobacco, alcohol and drugs that some people use for the way they feel. This chapter gives plain facts. Build the picture of what they harm.

Draw it first

Draw what each one can harm

1 Draw the lungs and the heart. Tobacco harms both.
2 Add the liver and the stomach. Alcohol harms both.
3 Add the brain. Alcohol and other drugs change how it works.

Tobacco smoke harms the lungs. You read about this in the last chapters. It also makes the heart and the blood tubes work harder. Tobacco holds nicotine, a drug that makes a person want more. Chewed tobacco harms the mouth. Tobacco smoke also harms people who breathe it near a smoker.

Alcohol is a drug that slows the brain. A person who has drunk alcohol reacts more slowly, loses balance and judges badly. This is why alcohol and driving never mix.

The liver breaks alcohol down. Drinking a lot, for years, can badly damage the liver. It also harms the stomach, the heart and the brain. Young bodies are still growing, so they are harmed more. Alcohol is also harmful during pregnancy.

Other drugs affect the brain and the nervous system. Some make the heart race. Some slow the breathing. A drug from an unknown source can be especially dangerous, because nobody knows what is in it.

Each one can harm more than the organs named here. These are the main ones.

A drug can lead to addiction. This means the body and mind come to need it, and stopping is very hard. Addiction is a health problem. It is not a weakness, and nobody should be shamed for it.

Worried about a drug, for yourself or for a friend? You can always tell an adult you trust, or ask a health worker.

Someone may have taken a drug and be very sleepy. They may not wake, or may have trouble breathing. Get help at once, and stay with them. Tell an adult near you, or call the emergency number in your place.

A medicine is a drug that treats or prevents an illness. A medicine helps only when it is taken the right way. The amount you take each time is the dose.

See it three ways

With things

With an adult, read the label on a medicine box. Find how much to take, how often, for how long, and the last safe day.

As a picture

In words

Too little medicine may not work. Too much can poison the body, for example the liver. So take a medicine only as the label or a health worker says.

Take only the medicine that was meant for you. Never share it. Never take more to feel better sooner. Keep medicines where small children cannot reach them.

The order matters. Ask first, then take the medicine the way you are told.

Try it

Read a medicine label

You need: an empty medicine box or packet, given by a grown up, paper and a pencil.

Be safe: Use an empty box only. Never taste, smell or take any medicine as part of an activity. Keep real medicine where small children cannot reach it.

Ask a grown up for a medicine box that is empty. Put the box on the table in front of you.
Find the dose, how often it is taken, and the use by date.
Write each one in a table like the example in the picture.

What you will see: The label tells you exactly how much, how often and until when. It leaves nothing to guess.

If you cannot try it, this is what happens.

A wrong idea many people have

If a little medicine helps, more will help more.

Why it feels right: More of a good thing often seems better.

The test that breaks it: The label gives one dose for a reason. Above that amount a medicine can harm the body. Too much of a common pain medicine, for example, can damage the liver.

What is true: Take a medicine only as a health worker or the label says. More is not better, and it can be harmful.

Key words

drug: anything, other than food, that changes how the body works.
medicine: a drug that treats or prevents an illness.
dose: the amount of a medicine to take each time.
addiction: a strong need for a drug that is very hard to stop.

Back to your guess

The answer is B: A medicine helps only in the right amount. Too much can harm.

A medicine helps when it is taken as directed. Too much, or the wrong one, can harm. Tobacco and alcohol can harm other people too.

Keep it

Copy this into your exercise book.

Tobacco, alcohol and other drugs can harm the lungs, heart, liver and brain. Addiction is a health problem. Take a medicine only as directed. Ask a trusted adult or a health worker for help.

Draw: Draw the lungs, heart, liver and brain. Under each one write a drug that can harm it.

Draw the inside of the body

Feel your body at work

Draw the path of food

A cloth for a gut wall

Draw what each nutrient does

Find the fat

Draw the model lung

Make a model lung

Draw an air sac and a capillary

Mist from your breath

Draw the loop of blood

Feel your pulse

Draw the results of the test

Test your pulse and breathing

Draw what each one can harm

Read a medicine label

Key words, A to Z