The
Science of
Snot Phlegm and
The Slimy Truth about
Breathing Written by
d l a n o d c a Fiona M
Author:
Fiona Macdonald studied history at
Cambridge University, England, and at the University of East Anglia. She has taught in schools, adult education and universities, and is the author of numerous books for children. Series creator:
Published in Great Britain in MMXVIII by Book House, an imprint of The Salariya Book Company Ltd 25 Marlborough Place, Brighton BN1 1UB www.salariya.com HB ISBN: 978-1-912006-14-4 PB ISBN: 978-1-912006-42-7
David Salariya was born in Dundee, Scotland.
He has illustrated a wide range of books and has created and designed many new series for publishers in the UK and overseas. David established The Salariya Book Company in 1989. He lives in Brighton with his wife, illustrator Shirley Willis, and their son Jonathan. Artists:
Bryan Beach David Pavon Caroline Romanet Andy Rowland Paco Sordo Diego Vaisberg Editor:
Jacqueline Ford
© The Salariya Book Company Ltd MMXVIII All rights reserved. No part of this publication may be reproduced, stored in or introduced into a retrieval system or transmitted in any form, or by any means (electronic, mechanical, photocopying, recording or otherwise) without the written permission of the publisher. Any person who does any unauthorised act in relation to this publication may be liable to criminal prosecution and civil claims for damages.
135798642 A CIP catalogue record for this book is available from the British Library. Printed and bound in China. This book is sold subject to the conditions that it shall not, by way of trade or otherwise, be lent, resold, hired out, or otherwise circulated without the publisher’s prior consent in any form or binding or cover other than that in which it is published and without similar condition being imposed on the subsequent purchaser.
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The
Science of
Snot Phlegm and
The Slimy Truth about
Breathing Written by
d l a n o d c a Fiona M
Contents Introduction 5 The breath of life
6
Protect and survive
8
Why do noses run?
10
Sinuses, tonsils and adenoids
12
The cold virus
14
What is hay fever?
16
Too much!
18
Why do we cough?
20
What are bronchitis and pneumonia?
22
Breathless 24 air No ˆ way! 26 Breathe easy! 28 Glossary 30 Index 32
Introduction
B
reathe in, breathe out... We all do it, every day and every night. Breathing is essential for life. It brings oxygen (a gas in the air) into our lungs. We need oxygen to keep our brains and bodies working properly. Without it – without breathing – we would die very quickly! Usually we don’t notice that we are breathing; it happens automatically. But sometimes, when we have a cold, or asthma or hay fever, we find breathing difficult. Our noses, throats, windpipes and lungs become clogged with sticky, slippery mucus; that’s the scientific name for snot and phlegm. We sniff and spit and cough and splutter. Too much snot and phlegm can look gross and make us feel miserable, but normally, they’re very useful. Read on, and find out more…
7
e f i l f o h t a e r The b Oxygen in…
en Inside the lungs, oxyg walls in passes through the th ir sacs) of millions of alveoli (a bes) into capillaries (tiny tu d blood carrying blood. Then re through cells carry the oxygen ts with our body, where it reac to od nutrients from our fo need. release the energy we Blood to heart
Blood from heart
Alveoli
T
he body parts used for breathing are known as our respiratory system. Together, they keep us alive. Each part has a special function. When we breathe in, air containing oxygen is sucked through our nose and throat, down our windpipe and into our lungs. When we breathe out, our lungs puff waste gases (carbon dioxide and water vapour) back up again and out into the air. From our nose right through to our lungs, our respiratory system is coated with sticky, slippery mucus. This works like oil in a machine to keep the system running smoothly. We need mucus to breathe!
Capillaries
On average, we use over 200 litres of oxygen every day. An amazing 20 percent is taken by the brain. It needs lots of energy to fuel the electrical signals it uses to function.
8
Throat Nose
Mouth Lungs
Windpipe
Fascinating fact
…Waste gases out
Red blood cells rough While oxygen passes th on, the alveoli in one directi e waste gases travel th opposite way, from red blood cells into the lungs. Waste gases are produced when our bodies use energy. They of are toxic, so we get rid them by breathing out.
60
20
Oxygen passes in Waste gases pass out
Alveoli
The air we breathe contains: 78.09% Nitrogen 20.95% Oxygen 0.93% Argon 0.039% Carbon Dioxide plus tiny amounts of rare gases. It may also contain up to 1% water vapour.
At rest, we take around 20 breaths per minute. But when we’re active, breathing gets faster. A marathon runner takes 45 breath s per minute, and a sprinter takes 60 .
s Mighty musthcrole stem comes from ugh our respiratory sy
eathe in, a The power to move air abdomen. When we br d an ck ba t, es ch r ou muscles in n, creating low pressure w do ks sin m ag hr ap di the out, the muscle called the flow in. When we brea air es ak m at Th t. es ch inside the our lungs. ds, squeezing air from ar w up es sh pu m ag hr diap Breathe IN
Breathe OUT
Lungs
Lungs Windpipe
Windpipe Diaphragm
Diaphragm
9
e v i v r u s d n a t Protec Don’t pick your nose! It’s better and safer to blow. Snot is often full of viruses and bacteria; you don’t want to get them on your fingers or spread them around.
What does snot say about you?
10
Black: a fungus! See a doctor!
Brown: there’s dirt up your nose
Red: your nose is bleeding
Green: bacterial infection
Yellow: you have a cold
White: inflamed nose lining
Normal snot is clear and runny. But when you’re ill, it can change colour.
S
not and phlegm act as powerful defenders, guarding the places where germs, dirt, dust, and other dangerous, irritating substances might enter the body. Mucus surrounds and captures all these ‘invaders’, forming extra– thick, sticky snot and phlegm that can be removed by coughing or blowing our nose. Mucus also carries white cells from our blood that fight harmful bacteria. And it protects the delicate inner surfaces of our respiratory system by stopping them from becoming rough, dry, scratched or cracked.
Oh dear, I don’t think snot is meant to be that colour!
Germ–eaters
Bacteria
Phagocyte
Phagocyte ‘swallows’ bacteria
Phagocyte destroys bacteria
Mucus in the respirato ry system contains millio ns of phagocytes: special w hite blood cells that ‘eat’ an d destroy disease-causin g bacteria. Fresh phagoc ytes are produced by the body all the time. Old, dead phagoc ytes are carried out of our nose or throat in phlegm and snot.
! How much? uce
I hope I don’t drop this!
On average, we prod s of between 1 and 1.5 litre tly os mucus every day, m But in our nose and lungs. in ed mucus is also produc as our other body parts, such s. It stomach and intestine ings, shields their delicate lin aste and helps food and w along. matter move smoothly
Mucus contains lysozyme, an enzyme (natural chemical catalyst) that fights infection. This was discovered when snot dripped from scientist Alexander Fleming’s nose into a dish of bacteria – and killed them!
Disgusting data Healthy mucus is stretchy because it contains mucins, which are chemicals produced in several different parts of our body. Mucins are shaped like long, microscopic threads. They tangle and stick to each other – just like cooked spaghetti – forming slimy, slippery, stretchy snot.
11
