Chapter 6 of 8

All 8 chapters
  1. 1Organs and systems, readunderstood
  2. 2Digestion, readunderstood
  3. 3Nutrients and diet, readunderstood
  4. 4Breathing, readunderstood
  5. 5Gas exchange in the lungs, readunderstood
  6. 6The heart and blood, readunderstood
  7. 7Pulse, breathing and exercise, readunderstood
  8. 8Drugs, alcohol and health, readunderstood

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

  • You picked A. Read on. At the end, the chapter comes back to your guess.

  • You picked B. Read on. At the end, the chapter comes back to your guess.

  • 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. A plain, schematic picture of blood going round the body. It is not a map of the real chambers. Four steps. A box labelled body at the bottom, a box labelled lungs at the top, and between them the heart in two halves, the right side on the left of the page and the left side on the right of the page. First a dashed arrow goes up from the body into the right side of the heart, marked less oxygen. Second a dashed arrow goes up from the right side to the lungs, marked less oxygen. Third a solid arrow goes down from the lungs into the left side, marked more oxygen. Fourth a solid arrow goes down from the left side to the body, marked more oxygen. Labels: lungs, body, right side, left side, heart, less oxygen, more oxygen.bodyright sidelungsleft sidelessoxygenheart

    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. A plain, schematic picture of blood going round the body. It is not a map of the real chambers. Four steps. A box labelled body at the bottom, a box labelled lungs at the top, and between them the heart in two halves, the right side on the left of the page and the left side on the right of the page. First a dashed arrow goes up from the body into the right side of the heart, marked less oxygen. Second a dashed arrow goes up from the right side to the lungs, marked less oxygen. Third a solid arrow goes down from the lungs into the left side, marked more oxygen. Fourth a solid arrow goes down from the left side to the body, marked more oxygen. Labels: lungs, body, right side, left side, heart, less oxygen, more oxygen.bodyright sidelungsleft sidelessoxygenheartlessoxygen

    2 The right side pumps the blood to the lungs. Add that arrow.

  3. A plain, schematic picture of blood going round the body. It is not a map of the real chambers. Four steps. A box labelled body at the bottom, a box labelled lungs at the top, and between them the heart in two halves, the right side on the left of the page and the left side on the right of the page. First a dashed arrow goes up from the body into the right side of the heart, marked less oxygen. Second a dashed arrow goes up from the right side to the lungs, marked less oxygen. Third a solid arrow goes down from the lungs into the left side, marked more oxygen. Fourth a solid arrow goes down from the left side to the body, marked more oxygen. Labels: lungs, body, right side, left side, heart, less oxygen, more oxygen.bodyright sidelungsleft sidelessoxygenheartlessoxygenmoreoxygen

    3 In the lungs the blood takes up oxygen. It goes to the left side of the heart.

  4. A plain, schematic picture of blood going round the body. It is not a map of the real chambers. Four steps. A box labelled body at the bottom, a box labelled lungs at the top, and between them the heart in two halves, the right side on the left of the page and the left side on the right of the page. First a dashed arrow goes up from the body into the right side of the heart, marked less oxygen. Second a dashed arrow goes up from the right side to the lungs, marked less oxygen. Third a solid arrow goes down from the lungs into the left side, marked more oxygen. Fourth a solid arrow goes down from the left side to the body, marked more oxygen. Labels: lungs, body, right side, left side, heart, less oxygen, more oxygen.bodyright sidelungsleft sidelessoxygenheartlessoxygenmoreoxygenmoreoxygen

    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.

A standing person from the front with the two lungs and the heart between them. The heart is a little to the left of the middle of the body, which is the right of the page. Labels: lungs, heart.lungsheart
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

A row of boxes joined by arrows: heart, then arteries, then capillaries, then veins, then back to the heart. Labels: heart, arteries, capillaries, veins.heartarteriescapillariesveinsheart

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.

A table with two columns, blood carries and to. Oxygen goes to the cells. Nutrients go to the cells. Carbon dioxide goes to the lungs. Waste goes to the kidneys. Labels: blood carries, to, oxygen, the cells, nutrients, the cells, carbon dioxide, the lungs, waste, the kidneys.blood carriestooxygenthe cellsnutrientsthe cellscarbon dioxidethe lungswastethe kidneys
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.

A table with two columns, part and job. Red cells carry oxygen. White cells fight germs. Plasma carries food. Platelets close cuts. Labels: part, job, red cells, carry oxygen, white cells, fight germs, plasma, carries food, platelets, close cuts.partjobred cellscarry oxygenwhite cellsfight germsplasmacarries foodplateletsclose cuts
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.

  1. Sit still for a minute. Turn one hand palm up.
  2. 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.
  3. 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 table with two columns, place and you feel. At the wrist you feel a beat. At the chest you feel a beat. Labels: place, you feel, wrist, a beat, chest, a beat.placeyou feelwrista beatchesta beat

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.

Check yourself

Try each one before you look. A wrong answer tells you where to go next.

  1. Which part does blood go to just after it leaves the right side of the heart?

    A plain, schematic picture of blood going round the body. The body is at the bottom, the heart in two halves in the middle, and the lungs at the top. Dashed arrows go from the body to the right side and from the right side to the lungs. Solid arrows go from the lungs to the left side and from the left side to the body. Labels: lungs, body, right side, left side, heart, less oxygen, more oxygen.bodyright sidelungsleft sidelessoxygenlessoxygenmoreoxygenmoreoxygenheart
    Tap your answer.

    1. Yes, that is right. The right side pumps blood to the lungs. There it picks up oxygen.

    2. Not this one. Blood goes to the body after the left side of the heart, not the right side. Go to S3.3.6. Try another.

    3. Not this one. Blood must go to the lungs first. Only then does it reach the left side. Go to S3.3.6. Try another.

    See the answer

    The lungs

    The right side pumps blood to the lungs. There it picks up oxygen.

    • If you chose B: Blood goes to the body after the left side of the heart, not the right side. Go to S3.3.6.
    • If you chose C: Blood must go to the lungs first. Only then does it reach the left side. Go to S3.3.6.

  2. What does the blood do in the lungs?

    Tap your answer.

    1. Yes, that is right. The air sacs and the capillaries swap gases. Oxygen goes into the blood and carbon dioxide goes out.

    2. Not this one. Blood picks up food in the small intestine, not in the lungs. Go to S3.3.2. Try another.

    3. Not this one. The muscles get their oxygen later, when the blood has gone round the body. Go to S3.3.6. Try another.

    See the answer

    It picks up oxygen and gives up carbon dioxide

    The air sacs and the capillaries swap gases. Oxygen goes into the blood and carbon dioxide goes out.

    • If you chose B: Blood picks up food in the small intestine, not in the lungs. Go to S3.3.2.
    • If you chose C: The muscles get their oxygen later, when the blood has gone round the body. Go to S3.3.6.

  3. What does the blood carry from the small intestine to the cells?

    Tap your answer.

    1. Yes, that is right. The tiny pieces of food pass into the blood in the small intestine. The blood carries them to every cell.

    2. Not this one. Carbon dioxide travels from the cells to the lungs, the other way. Go to S3.3.6. Try another.

    3. Not this one. Oxygen comes from the lungs, not from the small intestine. Go to S3.3.6. Try another.

    See the answer

    Nutrients

    The tiny pieces of food pass into the blood in the small intestine. The blood carries them to every cell.

    • If you chose B: Carbon dioxide travels from the cells to the lungs, the other way. Go to S3.3.6.
    • If you chose C: Oxygen comes from the lungs, not from the small intestine. Go to S3.3.6.

  4. Which blood vessels carry blood away from the heart?

    Tap your answer.

    1. Not this one. Veins bring blood back to the heart. Think of them as the return road. Go to S3.3.6. Try another.

    2. Not this one. Capillaries are the tiny tubes between arteries and veins. Go to S3.3.6. Try another.

    3. Yes, that is right. Arteries carry blood away from the heart. The pulse you feel at the wrist is the push along an artery.

    See the answer

    Arteries

    Arteries carry blood away from the heart. The pulse you feel at the wrist is the push along an artery.

    • If you chose A: Veins bring blood back to the heart. Think of them as the return road. Go to S3.3.6.
    • If you chose B: Capillaries are the tiny tubes between arteries and veins. Go to S3.3.6.

  5. Why is the heart in two halves, like two pumps?

    Tap your answer.

    1. Not this one. Both halves work all the time. Each has its own job. Go to S3.3.6. Try another.

    2. Not this one. The heart pumps only blood. Air is moved by the chest. Go to S3.3.6. Try another.

    3. Yes, that is right. The right side pumps to the lungs and the left side pumps to the body. The blood goes through the heart twice on each trip.

    See the answer

    One half sends blood to the lungs and the other sends it to the body

    The right side pumps to the lungs and the left side pumps to the body. The blood goes through the heart twice on each trip.

    • If you chose A: Both halves work all the time. Each has its own job. Go to S3.3.6.
    • If you chose B: The heart pumps only blood. Air is moved by the chest. Go to S3.3.6.

  6. From an earlier chapter

    Which gas passes from the air sacs into the blood?

    Tap your answer.

    1. Not this one. Carbon dioxide passes out of the blood. Oxygen goes in. Go to S3.3.5. Try another.

    2. Yes, that is right. The air in the sacs has more oxygen than the blood, so oxygen passes into the blood.

    3. Not this one. Smoke is not a gas the body wants. It harms the lungs. Go to S3.3.5. Try another.

    See the answer

    Oxygen

    The air in the sacs has more oxygen than the blood, so oxygen passes into the blood.

    • If you chose A: Carbon dioxide passes out of the blood. Oxygen goes in. Go to S3.3.5.
    • If you chose C: Smoke is not a gas the body wants. It harms the lungs. Go to S3.3.5.

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.

Reading with a child? A short page for the adult: what this chapter teaches and three questions to ask.

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