Making Use of Science and Technology
BREATHING MADE EASY
A unit for 13 - 14 year olds
sponsored by Glaxo Wellcome plc.
BREATHING MADE EASY is one in a series of units entitled Making Use of Science and
Technology.
The project was developed at the Chemical Industry Education Centre at the:
Department of Chemistry
University of York
Heslington
York, YO10 5DD
Telephone:
Fax:
e-mail:
01904 432523
01904 434460
[email protected]
© Chemical Industry Education Centre
First Published 1996
ISBN 1 85342 562 1
The copyright holders waive the copyright on the material which follows to the extent that teachers may
reproduce this material for use with their students in the establishments for which the material was purchased.
For all other purposes permission to reproduce any of this material in any form must be obtained from the
Chemical Industry Education Centre. The material may not be duplicated for lending, hire or sale.
Acknowledgements
The author gratefully acknowledges the considerable assistance given by Frank Ellis,
Glaxo Wellcome Research and Development, Simon Taylor and other members of the
Chemical Industry Education Centre team and Beth Thomas who hand wrote the letter on
sheet E2.
Author: Ann Lawrence, Joseph Rowntree School, York on secondment to the Chemical Industry
Education Centre
Cover photograph: John Olive
Teachers' Notes
Breathing made easy
Introduction
Asthma is the most common chronic childhood condition in the Western world. As many as 1 in 7
children are likely to suffer from asthma. In the UK alone, nearly 2000 people die annually because
of asthma and the death rate is rising. However, any asthmatic who is being treated with modern
medicines can enjoy an active life.
This package aims to cover aspects of the topic of breathing by looking at the causes and treatment of
asthma.
What the pupils do:
• role play as 'patients' and 'doctors'
• written work, including diagram construction and data interpretation
• group practical work and demonstrations
The main areas of study are:
• lung structure and function
• gas exchange and the effects of smoking
• investigation of peak flow and other related activities
• the treatment of asthma
Author's Note
This package is not intended to be used as a medical document for the diagnosis and treatment of
asthma. The diagnosis of asthma must be left to suitably qualified medical staff. No instructional
information is included on how to deal with a person suffering from an asthma attack.
The resource should not be regarded as a basis for a school policy on asthma. Asthma UK provides
free information for primary and secondary schools on developing an asthma policy for schools and
how to deal with asthma attacks. The address is:
Asthma UK
Providence House
Providence Place
London, N1 0NT
Telephone:
020 7226 2260
Facsimile:
020 7704 0740
Website:
http://www.asthma.org.uk/
i
Teachers' Notes
Using this teaching resource
During school-based trials of this resource, teachers mainly made use of it with 13-14 year olds.
Some teachers selected activities for students who were younger, older and/or with special needs.
Thus, the resource can be considered to be a 'dip-in' resource from which teachers select those
activities which most suit the needs of their students.
The resource is organised into teachers' notes and pupil sheets. Some pupil sheets are intended for
individual use, others for group activities. The pupil sheets are on loose pages for ease of copying.
You are asked to pay particular attention to the section 'A word on SAFETY' on page vi before
commencing any activity which involves pupils in physical exercise.
List of equipment
Most of the equipment required is likely to be present in a secondary school science department. Only
one item, a peak flow meter, is an obvious exception. Equipment is listed in the teachers' notes at the
start of every activity.
ii
Teachers' Notes
Contents
Overview
iv
Links with the Curricula of England and Wales and Scotland
v
A word on SAFETY
vi
Teachers' Notes
Activity 1: Role Play
1
Activity 2: Breathing and Asthma
3
Activity 3: Gas Exchange
5
Activity 4: Peak flow profiles
8
Activity 5: Counting breathing rate and pulse rate
10
Suggestions for Other related activities
12
Additional written exercises
15
Appendix
17
Questions for diagnoses
Patients with problems
The asthma quiz
Lung model
Asthma
Ciliated cells and other exercises
Using a peak flow meter
Peak flow profiles (different sheets for different abilities)
Counting pulse rates and breathing rates
P1.1
P1.2
P2.1
P2.2
P2.3
P3
P4.1
P4.2-4.4
P5
Pupil Sheets
The following sheets related to optional activities
Measuring lung volume
Comparing inhaled and exhaled air
Making model ribs
P6
P7
P8
Making a lung mobile
A letter
The treatment of asthma
Asthma inhalers
E1
E2
E3
E4
iii
Teachers' Notes
Overview
Activity
1. Role Play
Timing
25 minutes
Outcome
Pupils develop awareness of asthma
triggers and suggest strategies to avoid
asthma attacks
Pupil Sheets
P1.1, P1.2
2.
Breathing and
asthma
50 minutes
Pupils learn about the breathing system and
what happens during an asthma attack
P2.1-P2.3
3.
Gas exchange
40 minutes
Pupils extend their knowledge of the
breathing system
P3
4.
Peak flow
profiles
40 minutes +
homework
Optional activity: requires peak flow
meter.
Pupils learn how the measurement of peak
flow profiles can help find suitable
treatments for asthma sufferers
P4.1-4.4
5.
Counting and
breathing and
pulse rates
50 minutes
Pupils develop an understanding of the
effect exercise has on the breathing system
P5
Suggestions for
other related
activities
Pupils deepen their knowledge of the
breathing system through:
• measuring lung volumes
• comparing inhaled and exhaled air
• movement of rib and intercostals
muscles during ventilation
P6-P8
Additional written
exercises
The following are suitable as additional
class or homework exercises:
• making a lung mobile
• a letter
• the treatment of asthma
• asthma inhalers
E1-E4
iv
Teachers' Notes
Links with Curricula of England and Wales and Scotland
Science in the National Curriculum of England and Wales
KS3 Programme of Study
Systematic enquiry
- use practical tasks and investigations to acquire scientific knowledge, understanding and skills
- work quantitatively
Application of science
- relate scientific knowledge and understanding to familiar phenomena and to things that are used
every day
- consider how applications of science, including those relating to health, influence the quality of
our lives.
- consider the benefits and drawbacks of scientific and technological development sin
environmental and other contexts
Communication
- use a wide range of scientific terms and symbols
- present their ideas through the use of diagrams, graphs tables and charts, using appropriate
scientific and mathematical conventions
Health and Safety
- take responsibility for recognising hazards in a range of work with living things, materials and
devices with which they are familiar
Life Processes and Living Things
Pupils should be taught:
- that animals have organs that enable life processes (breathing) to take place
- ways in which some cells, including ciliated epithelial cells, are adapted to their function
- how smoking affects lung structure and gas exchange
- that the abuse of drugs affects health
- body's natural defences may be enhanced by medicines
Curriculum and Assessment in Scotland
Environmental Studies (5-14)
SCIENCE: Understanding Living Things and the Processes of Life
By the end of S2 a pupil's curriculum should have included study of
- the processes of life – respiration (breathing)
- applications of biological science in medicine;
The processes of life
Levels D and E
- the structure and functions of the major parts of the body as they relate to the processes of
respiration
HEALTH EDUCATION: Health and safe living
Health and safety in the environment
Levels D and E
- issues which have a bearing on health eg. lifestyle in relation to a chronic disease
v
Teachers' Notes
A word on SAFETY
Some of the suggested physical activities in this resource will require volunteers. Care must be taken
in the selection of the volunteer. The following guidance is adapted from CLEAPSS School Science
Service Laboratory Handbook.
There must be no pressure from the teacher or peers on pupils unwilling to take part.
The teacher should announce to pupils that they should not volunteer to do the exercises if they are
suffering from colds, minor ailments, bronchial conditions (such as asthma), heart conditions, or
suffer from epilepsy.
Any exercise carried out should not be excessive and arranged so that it is completely safe;
competition between pupils should be discouraged.
Gentle exercise would not normally be expected to lead to 'unusual' breathing. Once activities are
underway, teachers should be on the watch for any unusual breathing in the volunteers. If it occurs,
the exercise must be stopped immediately and the volunteer seated and observed till their breathing
returns to normal.
After the exercise, pupils should be seated and observed carefully as heart and pulse rate are
measured.
Anyone fainting or complaining of feeling faint should be laid down with legs slightly raised (cover
those wearing skirts). When fully recovered, allow the pupil to sit in the fresh air with a friend.
Notes for selected apparatus
Mouthpieces, everytime a mouthpiece is used, after each pupil it should be changed or disinfected by
immersion in a freshly prepared disinfectant. Mouthpieces should be sterilised in 70% ethanol and
washed in water before use. Care must be taken with ethanol since it is flammable. (See section
15.12.3 (Chemical disinfection) in CHEAPSS). Note: ordinary household disinfectants are not
suitable.
vi
Teachers' Notes
Activity 1: Role play
How to begin . . .
You might like to show the Asthma UK flash movie "What is asthma all about?" (details on page i),
which is aimed at top juniors. However, it is suitable for older pupils
The role play
Resources:
Pupil sheets P1.1, P1.2
Aim
Pupils:
become aware of some 'triggers' of asthma attacks
think about strategies to avoid attacks.
Sheet P1.1, Questions for diagnoses, consists of questions that could be asked of a person suffering
from asthma type symptoms. All of the questions must be considered even if a 'yes' answer is
obtained on route to the end. In each case, there is no clear cut diagnosis. The pupils may like to
suggest further investigation for some of the cases.
On sheet P1.2, Patients with problems, five imaginary patients are described. Mount the description
of each patient onto a separate card. If interest is high, you may wish to add a few patients of your
own. These could suffer from other common ailments such as a heavy cold, hayfever or stress to
make the list more varied.
In the role playing exercise some pupils play 'patients'. They are just given one of the patient
descriptions from P1.2. Other pupils act as 'doctors' and are given P1.1.
Time will be needed so that the pupils playing patients can read their histories while those playing
doctors think about how to interview the patients sensitively.
Alternatively, pupils can be given all the descriptions and the diagnostic questions. They can then, in
groups, discuss and diagnose as many of the patients as time allows.
It is important to stress that proper diagnosis can only be made by suitably qualified people and
should any information lead a pupil to suspect that they have asthma, or other problems, they
should consult their own doctor.
Possible outcomes
Patient A - perhaps has asthma triggered by fur as symptoms occur on visits to the friend's house
where there is contact with cats. There are no animals on the farm. Goldfish are good pets for asthma
sufferers as they do not trigger symptoms. Stress and/or exercise could be triggers since rushing to
catch the school bus produces symptoms. Further investigation might include avoiding cats but
continuing to exercise; then, if symptoms persist the patient could try to avoid strenuous exercise.
Patient B - It seems unlikely, but not impossible, because of the amount of time spent with canaries,
that canary feathers are the asthma trigger. Symptoms appeared when in contact with house dust
which is known to be a major trigger. The open windows in May could also suggest pollen as a
trigger. The avoidance of house dust and/or pollen seems to be the first course of action.
1
Teachers' Notes
Patient C - the horse hair is a possible trigger but since this person is already in contact with cats and
dogs, the more likely trigger is feathers in the new pillow and duvet. It seems sensible not to use
these for a while and see if the symptoms disappear. The other possibility seems to be the recent
contact with cigarette smoke and it may be necessary to ask for a change to be made at work.
Patient D - it is possible that exercise induced asthma may be the problem but it may also be a rarer
case of allergies to food. The aubergines, yoghurt and nuts are possibilities; the way to tackle this
may be to remove these food items one at a time to see if symptoms improve.
Patient E - the information could suggest that having an infection brings on symptoms. Having
attacks at night is a major problem for some asthma sufferers since lack of sleep affects normal life in
many ways. It may be that the contact with cold air is a problem. Asthma sufferers are often advised
to have 'flu jabs before the onset of winter and to wrap up well before going out in cold weather. It
seems unlikely that the new pet has caused symptoms since another dog is present in the house, but
again, this is not impossible.
Drawing the lesson to a conclusion
Ask pupils to design a poster or leaflet advising asthma sufferers about avoiding attacks.
Pupils can add further advice as they complete other activities from the resource, providing an
opportunity for them to assess their own learning.
Possible rules that pupils might suggest:
Asthma can be triggered by many things so there are a number of precautions that can be taken to
avoid attacks:
•
•
•
•
•
•
•
•
•
•
take extra care of yourself to try and prevent a cold or an infection
avoid house dust and vacuuming
don't play in long grass or in areas where there is a lot of pollen
avoid being near people who are smoking
stay away from animals with fur or feathers
wrap up warm on very cold days; there is no need for you to miss out on playing in the snow
for instance
don't eat those foods which may upset you
leave yourself plenty of time to do things; don't rush around and become stressed
if necessary, remember to use your inhaler before you take exercise
if you have been prescribed a special inhaler for prevention of attacks remember to use it
regularly as you have been instructed; if you use a peak flow meter you will be able to see
your asthma is getting better or worse
The most important thing is to follow your doctor's advice.
2
Teachers' Notes
Activity 2: Breathing and Asthma
Resources:
Pupil sheets P2.1 - P2.3
Scissors
Glue
Aim
Pupils:
develop an appreciation of the impact of asthma in the UK
learn about the breathing system
learn about the effect of asthma upon the breathing system.
Background information
Asthma is the only treatable, chronic condition in the Western world that is increasing in prevalence.
The questions on P2.1, The asthma quiz, are suggested as a light-hearted way to introduce pupils to
facts and figures concerning asthma.
Answers to the quiz, plus some additional data:
•
1c more than a million of these are under 18
•
2a in the UK, 1 in 20 adults have asthma
•
3b
•
4c annually asthma costs an estimated £400 million in lost productivity, £70 million in sickness
and invalidity benefit
•
5b
•
6c
•
7b
The apparent increase in the incidence of asthma may be due to increases in:
• air pollution
• the use of central heating which has led to an increase in the population of the house dust mite
• diagnosis of the illness by doctors.
After discussing the quiz, you may like to suggest to the class that they calculate the likely number of
pupils who suffer from asthma in your school. The pupils will need to know the number of pupils
attending the school and divide this number by 7. Do not ask your class if any of them suffer from
asthma. Some pupils do not like to admit that they are asthmatic though some may volunteer the
information.
The activities
P2.2 & P2.3, Lung model and Asthma
In order to understand what asthma is, it is important to know something about the human breathing
system. On P2.2, Lung model, pupils are provided diagrams of the lungs.
Note: The two sides of P2.2, page 1 must be photocopied back to back so that the two diagrams match
as closely as possible. Pupils cut down the line indicated on the reverse of P2.2, page 1 and
then glue the two halves to P2.2, page 2 so that the letters A, B, C and D match up.
3
Teachers' Notes
P2.3, Asthma, gives a simple description of the breathing system. The first section, The breathing
system, helps pupils complete their lung model.
The third section, What causes asthma?, reminds pupils of the triggers they learnt about in the role
play activity. Substances which trigger symptoms are known as allergens. Asthma caused by
allergens is known as atopic or allergic asthma. The most important allergens are those we inhale
indoors - particularly those derived from the faeces of the house dust mites, Dermatophagoides
pteronnyssinus and D. farinae. There are other triggers of asthma such as cold air, exercise and
stress. Asthma, not caused by allergens, is known as intrinsic or non-allergic asthma.
You should explain that asthma is a chronic condition (that is, always present even when no
symptoms are evident). Chronic, however, does not imply that the condition is necessarily serious or
life threatening. The final paragraph explains in simple terms how asthma attacks can be avoided. If
you, or your pupils, want to go into more detail about the medicines used in the prevention and
treatment of asthma, further information is given in the appendix, page 17.
4
Teachers' Notes
Activity 3: Gas exchange
Resources: Pupils sheet P3
standard biology text books
scissors
Aim
Pupils:
extend their knowledge about gas exchange in the breathing system
learn about the impact of smoking on the breathing system
The pupil sheets are divided into six sections. Each gives the pupils an opportunity to deepen their
knowledge about aspects of the breathing system. You may wish to use one or all of the sections,
either during a lesson or as homework exercises.
Answers to questions on P3
Ciliated cells, page 1
Diagram labels:
c = cilia
n = nucleus
g c = goblet cell
Q.
What do you think might happen if too much mucus is made?
A.
Excess mucus around the cilia will stop them beating. The movement of mucus towards the
pharynx is hence reduced and the airways become blocked. This is similar to the effect of
smoking on the cilia.
Gas exchange, page 1
The correct matching of adaptations with advantages is shown in the table below.
feature/adaptation
advantage
thin (one cell layer thick)
allows O2 and CO2 to pass through more easily
moist
gases diffuse more easily in solution
millions of tiny air sacs (~150 gives a massive surface area over which gas exchange
million in each lung)
can take place
well supplied with blood
blood is the transporting medium for O2 and CO2 around
the body
How big is the inside surface of your lungs?, page 2
It is thought that the number of alveoli can be between 250 and 350 million. This gives a surface area
over which gas exchange can take place of about 75 m2. The following areas can be used to provide
comparisons:
a football pitch
a tennis court
an average school laboratory
external body surface
~ 500 m2
~ 80 m2
~ 50 m2
< 2 m2
In other words, the area contained within the lungs is about the size of a tennis court and 40 times
greater than the external body surface.
5
Teachers' Notes
Comparison of inspired and expired air, page 2
Q1. The completed table should contain the following figures:
oxygen
carbon dioxide
nitrogen
water vapour
Inspired air %
20
0.03
79
variable
Expired air %
16
4
79
saturated
Similar values to these can be found in most biology text books.
Q2. The words 'lower' should be crossed out from the text.
Q3. Why is there little or no change in the percentage of nitrogen?
A.
Nitrogen is neither used up nor produced in any body process.
Background information: Respiration and breathing
The processes of respiration and breathing are often confused. It would be worthwhile, for the more
able, to try and distinguish between the two processes although they do not come up on the pupils
sheet.
Breathing - is the exchange of gases between an organism and its environment. The gas exchange
surface varies considerably between organisms, e.g. leaves of plants, cell membrane of unicellular
organisms, tracheoles of insects, gills of fish, lungs of mammals. Gas exchange surfaces have similar
features such as high surface areas, thin, moist surfaces and a plentiful supply of transport medium,
e.g. blood, if this is needed. The purpose of breathing is to gain oxygen from the environment and
excrete carbon dioxide into the environment
Respiration is the process that takes place in all living cells of both plants and animals which produces
energy. In aerobic respiration a supply of oxygen and a respiratory substrate are required. The
process produces useful energy. Carbon dioxide and water are waste products. The most common
substrate is glucose.
glucose + oxygen → carbon dioxide + water + energy
If there is time at the end of a lesson, or for homework, you might like to try an idea (adapted from
Words in physics, SSR March 1989, 70 (252)) to help students to remember the distinction between
respiration and breathing. The pupils are asked to write a short poem describing each process. It is
constructed as follows:
The first line has one word and names the process.
The second line has two words and describes the first line.
The third line has three words and tells what the first line is doing.
The fourth line has four words and tells what the writer thinks/feels about the first line.
The fifth line renames the first line in a single word (if possible).
You may like to change the 'rules' to some of the lines, so that they have to contain correct
information about the processes rather than 'feelings'.
The pupils could also try to describe asthma. Some examples:
Respiration
Energy production
Using up oxygen
Lets me do things
Oxidation
Breathing
Takes air
Exchange of gases
In order to live
Lungs
6
Asthma
Difficulty breathing
Narrowing of airways
I can't breathe properly
Allergy
Teachers' Notes
Gas exchange in the alveolus, page 3
Diagram labels:
c= capillary
b f = blood flow
r b c = red blood cells
open arrow
diffusion of carbon dioxide from the blood
bold arrow
diffusion of oxygen into the blood
a= air in and out,
The effects of smoking on the breathing system, pages 3 & 4
Smoking has a number of effects on the body. It damages the structure of the lungs and impairs their
ability to exchange gases. Pupils are asked to put into the correct sequence a series of statements
which describe the impact of smoking on the breathing system. Their answer should read as follows:
Smoke contains tiny particles. These get trapped by the cells in the breathing tubes. The
cells of the breathing tubes make extra mucus. The breathing tubes get blocked up. This
lead to 'smokers cough'. If you then get an infection this can lead to chronic bronchitis.
You may like to offer a more detailed explanation:
Inhaled smoke contains many tiny particles. The particles become trapped by the ciliated
cells which line the breathing tubes. More mucus is produced which has the effect of
stopping the cilia from beating. Once the cilia stop beating, the so-called 'mucus escalator'
towards the pharynx is also halted. This combination of events leads to 'smoker's cough'. If
the tubes subsequently become infected, then the person may suffer from chronic bronchitis.
Repeated coughing may lead to damage to the delicate alveolar walls. This leads to a
reduction in the surface area over which gas exchange takes place. Hence breathing becomes
a problem. This condition is called emphysema.
A simple diagram to show these changes is included on P3, page 4 along with two questions:
Q1. What difference can you see between these air sacs?
A.
The damaged air sac has an inner lining which is 'smoother' than a normal air sac.
Q2. What effect might this have on gas exchange?
A.
This gives a reduced surface area so there would be less gas exchange.
7
Teachers' Notes
Activity 4: Peak flow profiles
Resources:
Pupil sheets P4.1-P4.4 (or P4.1, P4.2a, P4.2b and P4graph)
peak flow meter
graph paper
This activity is optional. The class will need at least one peak flow meter. A meter is available from a
pharmacist (cost ca. £11.50). It has a removable mouthpiece which can be sterilised using a suitable
disinfectant solution (see notes on Safety, page vi).
Aim
Pupils:
learn how peak flow profiles can be used to monitor the lung function of an asthma sufferer and
help measure the effectiveness of treatment
Background
One of the most important measurements in the study of asthma is called peak flow.
Peak flow is a measure of the maximum air flow achieved during a forced expiration (following a full
inspiration). It is measured in litres/second or litres/minute. Peak flow varies according to the age,
sex and height of an individual. There are predictable normal values with which test values can be
compared. The information provided with peak flow meters gives examples of how peak flow can be
used to measure the effect of asthma on lung function.
Regular peak flow measurements can assist doctors in finding the most suitable treatment for asthma
sufferers. Peak flow values are taken several times each day and recorded on a chart. Values are
joined together to produce a peak flow profile.
Measurement of peak flow
Pupil sheet P4.1 Using a peak flow meter introduces the concept of peak flow through the practical
activity of pupils measuring their own peak flow. If you suspect that pupils may give low test results,
or if there is only one peak flow meter available, you may wish to demonstrate this activity.
The following examples involve drawing charts and interpretation skills. Three examples are given of
peak flow profiles:
P4.2
P4.3
P4.4
a boy without asthma
how a peak flow profile can help
exercise induced asthma
P4.2 can be replaced by the simplified sheets P4.2a and P4.2b. If the simplified sheets are used then
P4.3 and P4.4 should be omitted. Graph paper for pupils who need help with drawing charts is
included (P4graph). On the P4graph:
.
The first two points of the peak flow profile for P4.2a are shown with dots ' ' and a solid line.
The first two points for the peak flow profile for P4.2b are shown with crosses 'x' and a broken line.
8
Teachers' Notes
Answers to sheets P4.2 - P4.4
P4.2
Example - a boy without asthma
2.
The peak flow values for a large number of individuals in this category would have been
added together and an average value calculated.
P4.2a A peak flow profile for a 12 year old boy
This 12 year old boy's peak flow results go up and down during the day. All of his results are
fairly close to 420 l/m.
P4.2b A peak flow profile for a 12 year old boy with asthma
The results for the boy with asthma also go up and down during the day. Compared with the
other boy, these results are lower and the variation between the highest and lowest readings is
greater.
P4.3
Example - how a peak flow profile can help
3.
The 12th day: his peak flow value increases.
The patient forgets to record the peak flow values on day 17 and 18.
P4.4
4.
The 20th day: his peak flow value decreases.
5.
The 23rd day: by keeping a peak flow profile, he can see that his values are decreasing
and this prompts him to restart his medicine.
Example - exercise induced asthma
1.
It goes down.
2.
It is fairly normal.
3.
After ~15 minutes, the drug will have its greatest effect, that is, it will be opening the
airways when this is needed.
4.
Asthma sufferers should remember to take preventative medicine a suitable length of
time before, for example, their PE lessons.
9
Teachers' Notes
Activity 5: Counting breathing rate and pulse rate
Resources:
Pupil sheet P5
stop clocks
Safety
Read the safety notes on page vi before the pupils carry out the following activities.
Aim
Pupils:
develop an understanding of what happens to the breathing system during and after exercise.
Activities
Before exercise the pupils should take the following measurements. These are known as the resting
rates.
Breathing rate can be counted by watching the chest rise and fall. In and out is counted as one breath,
not two. It is probably easier for someone to count their own breathing rate, but when pupils do this
they tend to breathe much faster than normal and end up with values that are far too high. Pupils
should be encouraged to breathe slowly to find a value for breathing rate per minute. Typical results
are around 14 breaths per minute, anything above 30 is too high.
Pulse rate can be counted at various places. The pulse can be felt anywhere where an artery crosses a
bone near the skin surface. The most usual places are at the wrist, temples and in the neck. The pulse
must be detected by pressing gently with fingers and not by using the thumb. This is because there is
also a weak pulse in the thumb which could cause confusion. Some pupils find this a difficult task to
do. (Some trial teachers felt that the neck pulse was easiest but others felt that this was not safe.
What you advise your pupils will depend on how responsible you feel they can be.) Pulse rate can
also be monitored by data logging equipment if this is available.
There can be a great range in pulse rate from less than 60 to 90 beats per minute. Fitter people tend to
have lower resting pulse rates than less fit people. (Miguel Indurain, winner of the Tour de France on
at least five occasions, has a resting pulse of 28/minute; Bjorn Borg, five times Wimbledon champion,
had a resting pulse of 32/minute). The return to normal resting pulse rate after exercise is a good
indicator of fitness. The shorter the time it takes to return to normal, the fitter the individual.
Pupils should use exercises known to you that are strenuous enough to bring about a change in
breathing rate, but not so demanding as to cause distress. These might include star jumps, running up
and down stairs, using exercise bikes. Whatever activity is chosen, due regard should be given to
safety, see page vi.
During sustained exercise, the demand for oxygen increases and the production of carbon dioxide
increases. The body responds by:
breathing deeper
breathing faster
pumping the blood through the lungs at a faster rate
dilating blood vessels near the skin surface to increase blood flow
10
Teachers' Notes
In consequence of these changes, more oxygen is gained, more carbon dioxide removed and excess
heat lost.
Short bursts of activity (e.g. sprinting, short distance speed swimming) can be done on one large
breath.
After exercise the above measurements (breathing and pulse rate) are taken again.
11
Teachers' Notes
Suggestions for other related activities
Please read the notes on SAFETY, page vi.
These activities vary in their difficulty and in the time taken to complete. You may like to pick and
choose which to do. It is better if pupils work in small groups.
Resources are listed with each activity.
Activity 6: Measuring lung volumes
Resources:
Pupil sheet P6
large bowl
bucket or bin
ca. 5 litre plastics drinks container (graduated in 0.5l)
plastic/rubber tubing
disinfectant solution
There are many ways of measuring lung volumes. Most schools have apparatus of some description
ranging from spirometers to graduated vessels such as bell jars, or - as suggested above - a large
plastics drinks container.
A simple method of measuring vital capacity and tidal volume is suggested on sheet P6. The lower
vessel should not be filled too full of water to prevent the water overflowing.
Terms which the students will need to know:
vital capacity - the maximum volume of air that can be breathed out after the deepest possible
inhalation; typical value ~2.5 litres (dm3)
tidal volume - the volume of air that is breathed in and out during normal relaxed breathing; typical
value ~0.5 litre
residual volume - the lungs cannot be completely collapsed or emptied of air; there is always a
certain amount of air remaining in the bronchial tubes, trachea etc. which is known as the residual
volume; typical value ~1.5 litres
More able students can calculate their pulmonary ventilation - the volume of air that enters their
lungs during a fixed time e.g. per minute
pulmonary ventilation (PV)
(litres per minute)
=
respiratory rate
(breathing rate per minute)
x
tidal volume
(litres per minute)
Activity 7: Comparing inhaled and exhaled air
Two methods are possible: the limewater or bicarbonate indicator methods. Teachers who trialled this
resource all preferred the limewater method. The bicarbonate method can be found in standard
biology text books.
The limewater method
Resources:
Pupil sheet P7
boiling tubes with bungs
tubes and T-pieces (diagram on sheet P7)
limewater
12
Teachers' Notes
SAFETY
Pupils must breathe gently so as not to swallow the limewater.
The mouthpiece should be removable and must be sterilised in an
appropriate solution.
This experiment assumes that pupils know that limewater goes milky when carbon dioxide is bubbled
through it.
The apparatus, see P7
The arrangement of the short and long tubes is very important. The long tubes should be as long as
possible so that a small volume of limewater can be placed in the tubes. This is because although
limewater is specific (it will only go cloudy/milky in the presence of carbon dioxide) it is not very
sensitive (it will not detect very low concentrations of carbon dioxide). It is less likely that pupils will
suck up a small volumes of limewater.
Pupils breath very gently in and out through the mouthpiece while pinching their nostrils together.
The mouthpiece should be removable and can be sterilised in an appropriate solution.
More able pupils, given two boiling tubes and the glass tubes already in the bungs, can be asked to
assemble the apparatus themselves. Before using the apparatus they should look at the arrangement
of the tubes in the diagram. They should see that they can only take air in from tube A and breathe air
out into tube B.
Results: The liquid in tube B should go cloudy/milky, showing that exhaled air contains more carbon
dioxide than inhaled air.
Extension: If you wish to show that carbon dioxide is an acidic gas, then use the same apparatus but
replace the limewater with a very dilute solution of universal indicator. The solution through which
exhaled air passes will show the presence of an acid.
Activity 8: Movement of ribs and intercostal muscles during ventilation
Resources:
*
Pupils sheet P8 pages 1 and 2
pieces of card
elastic* or elastic bands (cut to produce a length of elastic)
paper fasteners
scissors
Elastic is not a perfect model, as when it is representing a relaxed muscle, it is stretched but under
tension.
The basic instructions are given on sheet P8, page 1.
When pupils fit a piece of elastic through holes A and B so that it is stretched, this represents the
external intercostal muscles relaxed (and at their longest). The model should look as in the diagram
(position 1) on sheet P8, page 2. When the muscles contract (and hence shorten), the ribs are moved
upwards (and outwards in reality).
13
Teachers' Notes
When the pupils fit the elastic through holes C and D so that it is stretched, this represents the relaxed
internal intercostal muscles. The model should look as in the diagram (position 2) on sheet P8,
page 2. When these muscles contract the ribs move downwards (and inwards in reality).
The internal and external muscles do this together so that one set of muscles are contracted when the
other set are relaxed. They are examples of antagonistic muscles. Pupils can feel this motion if they
put their hands on their ribs and breathe slowly.
An explanation for movement during ventilation
Details of inspiration and expiration do not appear on the pupil sheets.
Inspiration and expiration occur as a result of pressure changes in the lungs compared to atmospheric
pressure. Air moves from an area of higher pressure to an area of lower pressure.
During inspiration the diaphragm contracts and changes from a dome shape to a flatter shape. The
external intercostal muscles contract (the internal intercostal muscles relax) and move the ribs
upwards and outwards. These contractions result in a greater volume in the thorax and a lower
pressure compared to atmospheric pressure. Hence air moves into the lungs.
During expiration the diaphragm relaxes and becomes dome shaped again. The internal
intercostal muscles contract (the external intercostal muscles relax) and move the ribs downwards
and inwards. These contractions reduce the volume inside the thorax and increase the internal
pressure compared to the atmospheric pressure. Hence air is pushed out of the lungs.
14
Teachers' Notes
Additional written exercises
These exercises are in order of increasing difficulty. They are suitable for either classroom work or
homework.
Exercise 1: Making a lung mobile - (lower ability)
Resources:
Pupil sheet E1
card
scissors
wool or string
pieces of thin cane
Pupils make a mobile to show the structure of the breathing system (this is not to scale).
Exercise 2: A letter - (all)
Resources:
Pupil sheet E2
There is obviously no right or wrong answer here but the pupils' letters of response will indicate their
understanding of asthma.
Exercise 3: The treatment of asthma - (higher ability)
Resources:
Pupil sheet E3
Aim
Pupils develop further their understanding of the treatment of asthma.
Teachers in the trial of this resource often made use of this to extend bright pupils in mixed ability
classes.
Answers to questions on E3, page 2
1. Preventers - medicines that are taken regularly which try to prevent a person having an asthma
attack.
Relievers - medicines that are taken to relieve an attack once it has started.
2. A bronchodilator is a medicine which opens up the breathing tubes.
3. Adrenalin has unwanted effects on the body such as raising the blood pressure and increasing the
heart rate.
4. Although this question is asking about some organic chemistry, it does not require any particular
knowledge though there are some rules to stick to. Mirror images or rotating the benzene ring
without changing the positions of the groups are not allowed. These two rules are shown on the
pupil sheet.
15
Teachers' Notes
There are ten possible molecules. The answers are below :
A
B
C
A
A
A
C
A
C
B
C
B
C
B
A
C
A
B
B
B
A
C
C
B
C
B
A
C
A
B
Exercise 4: Asthma inhalers - (higher ability)
Resources: Pupil sheet E4
Aim: The inhaler used to deliver medication contains some interesting science of its own. Pupils are
given a chance to develop their awareness of how the inhaler works.
Only the answer to question 2 can be found from the sheet; the answers to the other questions will
have to be researched.
Answers to questions
1. nose/mouth, trachea, bronchus, bronchioles, alveoli
2. The medicine will go straight to where it is needed, that is, its effect is almost immediate.
A smaller dose is required compared to if the medicine had to be swallowed.
3. There are a number of possibilities here, for example:
- pressurised container protect from sunlight and direct heat
- do not pierce or burn, even after use
- keep out of reach of children
4. There is no right and wrong answer here.
The arguments will probably go along the lines that although the amounts of CFCs in inhalers are
small, and although they are being used for medical purposes, if they damage the ozone layer their
use is to be opposed and alternatives sought.
5. Can A contains a low boiling liquid under pressure. This moves through hole C into the space B.
The plug is held in place by the spring and so prevents the liquid from escaping.
When the spring is squeezed by the inhaler user, the plug blocks hole C. Hole D allows the liquid
to escape from the space B, into the atmosphere via the tube. As the pressure drops rapidly, the
low boiling liquid vaporises.
16
Teachers' Notes
Appendix
Lung structure and function
Our lungs are contained within the chest or thorax. Each lung is entirely enclosed by a pair of pleural
membranes. Between the membranes is the pleural cavity enclosing pleural fluid which allows the
lungs to move easily against the thoracic wall. The heart is also found within the thorax, slightly left
of centre. The heart and lungs are separated from the rest of the abdomen by a dome shaped sheet of
muscle called the diaphragm. The contents of the thorax are protected by the ribs. Between the ribs
are the internal and external intercostal muscles. The intercostal muscles, ribs and diaphragm are
involved in the inspiratory and expiratory movements which are responsible for taking air into and out
of the lungs.
When we breathe, air enters our body through the mouth or nose. We tend to breathe through our
noses more often than through our mouths. There are a number of reasons for this. It allows us, for
example, to do other things such as talking and eating. As air passes through the nasal cavities it is
warmed and filtered of particles by the hairs that line the cavities. It then passes down the windpipe or
trachea. The trachea divides into two smaller tubes called bronchi. The bronchi further divide into
finer tubes called bronchioles. The bronchioles are the first airway branches not to contain cartilage
for support. At the ends of the bronchioles are the alveoli. It is here that gas exchange takes place.
Gas exchange is the “swapping” of oxygen for carbon dioxide. Oxygen is needed for the reactions of
respiration.
Ciliated cells
The lining of the trachea, bronchi and bronchioles consists of ciliated epithelial cells. These cells have
microscopic hairs or cilia on them. The hairs move rhythmically, sweeping away dust particles and
moving the mucus that is produced by special goblet cells. These cells are excellent examples of
specialised cells. The cilia beat towards the pharynx moving mucus in this direction so that it is
swallowed. Trapped dirt and bacteria is thus prevented from reaching the lungs. Smoking a single
cigarette can stop the cilia beating for several hours.
The treatment of Asthma
The body produces its own natural bronchodilator - the hormone adrenalin. Adrenalin is not a
completely suitable substance to use in asthma attacks because it has other effects that are not
desirable in this situation. For example, it increases the heart rate and increases blood pressure and
also stimulates brain function. However its structure provided a starting point for scientists to develop
a better compound.
The structure of adrenalin in complete, abbreviated and a simplified form is:
HO
HO
H
HO
H
H
H
H
C
C
H
HO
N
OH H H
C
CH(OH)CH2NHCH3
H
H
17
Teachers' Notes
By altering one of the hydroxyl groups and the methyl group, the unwanted side effects of adrenalin
were removed. The new substance was named salbutamol and its structure is:
HOCH2
HO
CH(OH)CH2NHC(CH 3)3
The changes that were made also meant that salbutamol would work for longer periods since it was
not broken down as quickly by the body as adrenalin. The drug salbutamol was first marketed in 1969
after many years of research and millions of pounds in cost.
There has been a further advance in the production of an asthma drug. The effects of salbutamol last
for about 4 hours which is not long enough for nocturnal asthma sufferers to get a good night's sleep.
The compound salmeterol has been developed which gives about 12 hours relief.
HOCH2
HO
CH(OH)CH2NH(CH2)6O(CH2)4
The extra long group attached to the molecule appears to give a longer protection for asthma for 12
hours or more. Although it is a bronchodilator and will relieve attacks, its onset of action is not as
rapid as with salbutamol. It is therefore not normally used for acute attack control but to keep the
airways open over a long period of time.
Preventative treatment - steroid treatment for asthma
One group of steroids, the corticosteroids, is used to treat asthma. Steroids are a special, wide-ranging
group of chemicals that are made naturally by the body and artificially in the laboratory.
Corticosteroids work by reducing the amount of inflammation, swelling and mucus in the bronchioles.
Steroids take much longer, often a period of weeks, to take effect compared to reliever inhalers.
Reliever inhalers only ease the symptoms of asthma rather than treating the underlying problem. The
steroids can be inhaled in much the same way as relievers, which reduces the dose when compared to
steroids taken by mouth in tablet form. Medicines for preventing symptoms must be taken regularly.
Inhaled steroids taken for the prevention of asthma must not be confused with anabolic steroids taken
by athletes. There are very few side effects from taking inhaled steroids. Steroid tablets taken long
term can have serious side effects which can include weight gain, thinning of the bones (osteoporosis),
increased blood pressure, stomach ulceration and a heightened risk of diabetes in those prone to it.
Children may grow more slowly.
Sodium cromoglycate, not a steroid, is usually prescribed as a first preventer for children. It can help
to prevent asthma, especially in children, by a totally different mechanism.
18
Teachers' Notes
The Inhaler
Aerosols
The boiling point of a liquid rises when pressure is applied to it and falls if less pressure is applied to
it.
Some substances have a boiling point which, under ordinary atmospheric pressure, is below normal air
temperature. Under such conditions such a substance will be a gas. But, if its pressure is raised, then
its boiling point will be raised also. If the new boiling point is above normal room temperature the
substance turns into a liquid. A substance with such a boiling point can be used as a propellant in an
aerosol spray can.
The substance which is to be sprayed is suspended in the propellant. The mixture is sealed in the can.
At room temperature some of the propellant vaporises and the pressure in the can rises. This raises
the boiling point of the liquid and so it remains as a liquid in the can. When the button is pressed, a
valve opens and a mixture of the spray material and the liquid propellant is forced out of the can by
the pressure of propellant gas in the container. Now, under normal air pressure, the propellant
vaporises leaving a spray in the form of a mist of fine droplets.
Asthma Inhalers
The development of the special inhaler used by asthmatics involved a great deal of technology and
took more than 10 years. It cost over £50 million.
The medicines that relieve asthma will work much better if they are inhaled since they will go directly
to the desired site of action, that is, the bronchial tubes. Inhaling asthma medicines also means that a
smaller dose of the medicine is needed than if the medicine had to be swallowed.
The metered dose inhaler (MDI) is probably the most commonly used inhaler. It works on similar
principles to other aerosols such as hair spray, polish etc. except that it delivers exactly the same dose
each time it is used.
The drug is equally suspended through the liquid in the canister and is forced into the aluminium
canister under pressure. At the mouthpiece end there is a separate section which constitutes the
correct volume for a dose of the medicine. When using the inhaler, it is held upside down so that the
liquid fills the separate section. When the canister is pressed, a valve closes off the metered section
from the rest of the canister and releases the contents of the metered section into the mouthpiece. The
liquid released from the canister quickly evaporates leaving the active medicine as a fine dust which is
breathed in.
19
Teachers' Notes
There must be co-ordination between pressing the canister and breathing in, otherwise the dose will be
wasted. Old people and young children may find this difficult, but ways of getting round this problem
have been overcome by using a spacer device.
normal position
actuated position
The propellants used in these canisters are chlorofluorocarbons (CFCs). This presents a problem with
respect to the environment. CFCs have been identified as one of the chemicals responsible for
depleting the Earth's stratospheric ozone layer.
CFCs belong to a family of compounds that are very unreactive, non-toxic and not flammable. These
properties make them suitable for uses such as propellants and refrigerant fluids. Crucial to their
usage in these areas is that they have the right boiling point - high enough to liquefy by compression
but low enough to vaporise easily.
In the mid 1970s, scientists realised that CFCs also had the potential to be dangerous. They are so
stable that they are likely to remain in the atmosphere for many years - more than 50. They make
their way into the upper atmosphere - the stratosphere. This is where you find the ozone layer, which
normally protects us from harmful ultraviolet radiation. In 1984 scientists of the British Antarctic
Survey discovered a 'hole' in the ozone layer above the Antarctic. Less ozone means that more
ultraviolet light can reach the Earth. Over exposure to ultraviolet light can lead to skin cancer.
Even though the amounts used are tiny and are for medical purposes, some pharmaceutical companies
have made it a priority to replace CFCs in their MDI products with a safe, reliable and affordable
alternative propellant. The amount spent on this type of project will virtually equal the spending on
the development of a totally new drug.
20
Notes
Notes
P1.1
Questions for diagnoses
START HERE
have you had a cold or
infection before latest
symptoms?
yes
colds and infections can
start asthma attacks
yes
high pollen counts are known to
bring on asthma
cold air may produce more attacks
yes
furry or feathered pets can bring on
asthma - goldfish are safe pets for
people with asthma!
yes
cigarette smoke can cause asthma
attacks
yes
feathers can cause asthma attacks synthetic fillings are usually no problem
yes
house dust, particularly the droppings of
house dust mites are known to be the
biggest cause of asthma attacks
no
are attacks worse at
particular times of
year?
no
do you or your friends
have any pets?
no
do you smoke or come
into contact with
cigarette smoke?
no
do you use feather
pillows or duvets?
no
are attacks bad when
your house is dusty or
being cleaned?
no
are attacks worse at
school during P E or
when running around?
yes
exercise can induce asthma
no
are there any other
particular times when
problems occur?
yes
in some cases, allergies can
bring on asthma attacks
P1.2
Patients with problems
Patient A
I live in the country on a farm. We grow crops such as wheat and barley, but don't
have any animals. I like to help with jobs before I go to school. I am often late and in
a rush. Sometimes I have to run down the lane to catch the bus to school. The only
pet I have is a goldfish. My best friend lives nearby and we take it in turns to visit
each other. My friend has two cats. I feel wheezy and breathless on occasions, like
early last week when I only just managed to catch the bus after doing too many
jobs. I sometimes feel wheezy when at my friend's house. My breathlessness does
not seem to be linked with any particular time of the year.
Patient B
I live in the country. I have a goldfish and 6 canaries. These pets are all in my
bedroom where most of my time is spent. I never seem wheezy in my own room. I
first noticed problems when I was off school with a badly swollen ankle. I was in the
sitting room when it was being cleaned and dusted. I felt really wheezy. I also had
problems last May when a spell of warm weather meant that lots of windows were
open. I felt a tightness in my chest and was breathless. I am a keen judo player, but
never have these kinds of problems then.
Patient C
I have worked in a local hotel for a number of years. I have a cat and two dogs. I
have never had any problems with breathing until lately. I have taken up horse
riding and have recently started cleaning smokers' rooms at the hotel. I have just
bought new pillows and a duvet which the cat promptly tore a hole in - there were
feathers everywhere! I felt very wheezy when clearing up the mess. I love taking the
dogs for walks in the countryside at all times of the year.
Patient D
I am a young child who has started to cough a lot and I feel breathless at certain
times. I have started to take part in more sports and I have been trying lots of new
foods. I like visiting my Aunty Theodora who cooks me different foods that I haven’t
eaten at home. Some of these foods include aubergines, natural yogurt and nuts
such as pistachios. Unfortunately, some of the times I’m breathless are when I’m at
my Aunty’s. Does this mean I won’t be able to visit again?
Patient E
I have just had a cold and a slight chest infection. I can’t seem to shake it off. I
keep coughing a lot, especially at night, which stops me from sleeping. I also feel
tight chested. I have realised that this seems to be a problem in winter time when I
leave the house to walk to school. Last week we bought a new pet dog from the
dogs home - we felt sorry for it! It will keep the other dog we have company.
P2.1
The asthma quiz
How much do you know about asthma?
Try these questions to find out!
1.
How many people in the UK have asthma?
a
b
c
2.
'flu
asthma
sickness
o
o
o
around 1 000 000
around 3 000 000
around 7 000 000
o
o
o
How many hospital admissions result from asthma each year?
a
b
c
6.
o
o
o
How many working days are lost because of asthma each year?
a
b
c
5.
1 in 7
1 in 70
1 in 700
What illness causes pupils to miss most school?
a
b
c
4.
o
o
o
What proportion of children in the UK have asthma?
a
b
c
3.
100 000
500 000
3 000 000
10 000
100 000
1 000 000
o
o
o
How much does asthma cost the NHS each year?
a
b
c
£4 million
£47 million
£473 million
o
o
o
7.
Over the last 10 years, the number of prescriptions for asthma
has...
a
b
c
halved
doubled
stayed about the same
o
o
o
medicines
P2.2, page 1
TASK
1.
2.
3.
Lung model
Glue P2.2 page 1a onto the back of this sheet. Ensuring borders match.
Cut the diagram round the border and then following the line running down
the centre, cut the diagram in half lengthways.
Glue the two pieces in the correct positions to sheet P2.2, page 2, matching
the letters A, B, C and D.
P2.2, page 1a
cut down this line
M
B
R
H
B
R
L
I
M
P2.2, page 2
3.
The diagrams show the position of your lungs in the body and the structure of
your lungs. Use the paragraph The breathing system on P2.3, page 1 to help
you to label the diagrams.
The air sacs are not shown on the diagram as they are very small.
P2.3, page 1
Asthma
The breathing system
Asthma is a condition which affects your lungs. The job of your lungs is to get
a supply of air. When we breathe, air enters our body through the mouth or nose. It
then passes down a tube which is called the windpipe or trachea (tra-key-a).
This tube divides into two smaller tubes called bronchi (bron-key). Each bronchus
then enters either the right or left lung. The lungs are separated from your digestive
system by a dome shaped sheet of muscle (shaped like an upside-down saucer)
called the diaphragm (die-a-fram).
The bronchi further divide into finer tubes called bronchioles (bron-key-ols). At the
ends of these fine tubes are the air sacs or alveoli (al-vee-o-lee). It is here that gas
exchange takes place. Gas exchange is the “swapping” of oxygen from the air for
carbon dioxide which has been made in the body.
The lungs are protected by the ribs. Between the ribs are muscles called intercostal
muscles. The heart is found in the chest between the lungs.
What an asthma attack feels like
A person suffering from asthma is often breathless and feels a tightness in their chest.
This is caused by a constriction (narrowing) of the air tubes. The tubes may also be
inflamed (hot, red and swollen) and lined with too much mucus (a thick liquid).
Breathing becomes very difficult indeed. The diagrams below show sections
through airways with and without swelling.
normal airways
swelling of the airways
P2.3, page 2
What causes asthma?
There are many possible causes of asthma. No-one completely understands this
complicated illness.
TASK
Read the following information carefully. Discuss it with a partner.
Underline anything which may cause someone to suffer from an asthma attack.
Certain substances, which do not affect most people, may trigger symptoms in
asthma sufferers. These substances are known as allergens. These can come from
dust, birds, furry animals or pollen. Exposure to cold air, exercise and even stress
have been known to cause asthma attacks. However, the most significant allergens
are those which come from the faeces (droppings) of house dust mites.
What can you do if you suffer from asthma?
It is sensible for asthma sufferers to avoid situations and substances that can cause
attacks. Modern medicines are used to both relieve and prevent attacks.
The medicines that relieve symptoms open up the airways very quickly. They are
taken when an asthma attack happens.
The medicines that prevent attacks are taken regularly. They make a person’s
breathing tubes less sensitive to the substances that would normally cause an
attack.
Inhalers are used to take these medicines. These should be kept out of the way of
young children.
Summary
Asthma is a serious problem but sufferers often live active lives. Famous people
including Ian Botham (international cricketer) and Adrian Moorhouse (Olympic gold
medal swimmer) have asthma and yet have reached the highest level of sporting
achievement. To do this they had to control their asthma by following their doctors'
advice and taking the medicines prescribed for them.
P3, page 1
Ciliated cells
The lining of the airways consists of ciliated epithelial cells. These cells have
microscopic hairs or cilia on them. These cells are excellent examples of specialised
cells. They have a special job to do.
The cilia move rhythmically, sweeping away dust particles that have been taken in
with inhaled air. They also move the mucus that is produced by special goblet cells.
The cilia move towards the pharynx (the back of the throat) so that the mucus is
swallowed. Dirt and bacteria trapped in this way are thus prevented from reaching
the lungs. A single cigarette can stop the cilia moving for several hours.
TASK:
Label the parts of the diagram showing ciliated cells
c
n
mucus secreting cell
(g
c
)
Q.
)
Asthma sufferers often produce too much mucus. What do you think might
happen if too much mucus is made?
________________________________________________________________________________________
________________________________________________________________________________________
Gas exchange
Gas exchange takes place in the alveoli of the lungs. The structure of the alveoli
make them suitable for gas exchange. Here are descriptions of certain features or
adaptations of the alveoli structure as well as some advantages of these
adaptations.
TASK:
Discuss the following adaptations and advantages with a partner and then match up
the adaptation with its correct advantage. Show your matching pairs with a line.
adaptation
advantage
the alveoli are very thin only one layer thick
gives a massive surface area over which gas
exchange can take place
their linings are moist
blood carries gases around the body
there are millions of them
(~ 150 million in each lung)
gases diffuse more easily when in solution
they are extremely well
supplied with blood
allows oxygen and carbon dioxide to pass through
more easily
P3, page 2
How big is the inside surface of your lungs?
A baby is born with about 30 million air sacs. The number of air sacs increases
rapidly. By the time a child is 8 years old the number has reached its maximum of
about 350 million.
TASK:
The large number of air sacs gives an area of about 70 to 75 m2. You can get an
idea of how big this is if you find out the area of
- a football pitch
- a tennis court
- your laboratory
- your external body surface
Comparison of inspired and expired air
Using a text book:
Q1.
Find the correct values to complete the following table.
Inspired air %
Expired air %
oxygen
carbon dioxide
nitrogen
water vapour
Q2.
The following sentences describe changes that take place in the alveoli.
Cross out the incorrect words where there is a choice.
The concentration of oxygen in the alveoli is higher/lower than the concentration of
oxygen in the blood. The oxygen dissolves in the moisture of the alveoli and diffuses
into the blood where it is picked up by red blood cells.
The concentration of carbon dioxide in the blood is higher/lower than the
concentration of carbon dioxide in the alveoli. Carbon dioxide diffuses from the
blood into the moisture of the alveoli and into the alveolus itself. It can then be
breathed out.
Q3.
Why is there little or no change in the percentage of nitrogen in
and expired air?
inspired
________________________________________________________________________________________
________________________________________________________________________________________
P3, page 3
Gas exchange in the alveolus
TASK:
Label the diagram:
The effects of smoking on the breathing system
Cigarette smoke has been known to cause asthma attacks. Smoking also has a
number of other dangerous effects on the body. Most of these are to do with
damage to the structure of the lungs. This damage makes it more and more difficult
to swap oxygen for carbon dioxide in the air sacs. Healthy air sacs are clean inside
and have a very large surface area.
TASK:
Smoking cigarettes can lead to a condition called chronic bronchitis.
The following statements describe the things that happen which lead to chronic
bronchitis. They are in the wrong order. Cut the statements out, discuss them with
someone else and try to put them into the correct order.
these get trapped by the cells in the breathing tubes
this leads to "smokers cough"
if you then get an infection
smoke contains tiny particles
the cells of the breathing tubes make extra mucus
this can lead to chronic bronchitis
the breathing tubes get blocked up
P3, page 4
Coughing may start to damage the delicate air sacs. This means there will be less
surface for gas exchange. Breathing becomes very difficult. This condition is called
emphysema. (em-fa-seem-a)
normal air sac
Q1.
damaged air sac
What difference can you see between these air sacs?
________________________________________________________________________________
________________________________________________________________________________
________________________________________________________________________________
________________________________________________________________________________
Q2.
What effect might this have on gas exchange?
________________________________________________________________________________
________________________________________________________________________________
________________________________________________________________________________
________________________________________________________________________________
There are other diseases that are linked to cigarette smoking. These include cancer
of the mouth, throat and lungs and heart disease.
Pregnant women are also advised not to smoke since it may cause their babies to
grow less well.
Smoking is bad for everyone, but particularly for people with asthma.
P4.1
Using a peak flow meter
One of the most important measurements in the study of asthma is called
peak flow. Peak flow is a measure of how much and how fast you can blow
out. It can be measured in litres per minute. There are normal, expected
values for peak flow which vary according to your age, sex and height.
Peak flow can be measured using a peak flow meter.
Using a peak flow meter
1.
Make sure the pointer is at zero. Hold the meter out in front of you and
put the mouthpiece near your mouth. Make sure that your fingers do
not stop the pointer from moving along the scale.
2.
Take in as deep a breath as you can.
3.
Put your lips tightly around the mouthpiece. With a short, sharp
blast, blow into the meter. You will see that the pointer will move
along the scale.
4.
Write the result down.
5.
Slide the pointer back to the beginning.
6.
Repeat the test two times more.
7.
The highest measurement is your peak flow result.
SAFETY
The mouthpiece must be sterilised before someone else uses it.
If your doctor thought you might have asthma, you would be asked to use a
peak flow meter regularly, several times each day. Your peak flow results
would be recorded on a chart and the measurements would then be joined
together to make a peak flow profile.
This peak flow profile can be compared with the normal, expected values,
This can help to provide a diagnosis and to check how effective the
treatment is.
P4.2
Example - a boy without asthma
subject
age
height
PNV
male
12
158cm
423 l/m
PNV = predicted normal value
time
peak flow l/m
08.00
400
09.00
425
13.00
440
15.00
400
20.00
412
22.00
430
-
-
08.00
423
13.30
412
16.00
435
20.00
422
22.00
430
Remember: peak flow is a measure of how much and fast a person
can blow out. It is measured in litres per minute.
The values in the table represent the highest of 3 values at each reading.
1.
Draw a chart of time of day against peak flow (l/m). Join the points
with straight lines.
This chart shows the values for a 12 year old boy without asthma. The
readings go up and down. The readings show diurnal (daily) fluctuations.
2.
Add a horizontal line to the chart to show the PNV for this subject.
How would this value have been calculated?
People without breathing problems show diurnal fluctuations. Those of
asthma sufferers show greater amplitude (greater differences between the
highest and lowest value) and may have actual values lower or different to
the normal.
P4.2a
A peak flow profile for a 12 year old boy
The table below shows the results for a 12 year old boy who does not have
asthma.
time
peak flow result l/m
08.00
400
09.00
425
13.00
440
15.00
400
20.00
410
22.00
430
08.00
420
13.30
410
16.00
430
20.00
420
22.00
430
1.
Using a piece of graph paper, draw a chart of these results. Put the
time of day on the x-axis (the bottom line) and the peak flow result on
the y-axis (the side).
2.
Join the points together with straight lines.
3.
For this 12 year old boy you would expect a result of about
420 l/m.
Fill in the missing words in the sentences below :This 12 year old boy’s peak flow results go _____ and _____ during the day. All
of his results are fairly _______ to 420 l/m.
P4.2b
A peak flow profile for a 12 year old boy with asthma
The table below shows the sort of results that a boy suffering from asthma
might give if he used a peak flow meter.
time
peak flow result l/m
08.00
350
12.00
400
14.00
325
20.00
350
22.00
375
08.00
370
12.00
350
14.00
400
1.
Using another piece of graph paper, draw a chart of these results.
Remember that the time of day goes along the x axis and the peak
flow result goes along the y axis.
2.
Join the points together with straight lines.
3.
Compare this chart with the one you drew for the other 12 year old
boy.
Complete the sentences below:The results for the boy with asthma also go ___ and _____ during the day.
Compared with the other boy, these results _____________________________
___________________________________________________________________
___________________________________________________________________
P4.3
Example - how a peak flow profile can help
subject
age
height
PNV
male (ex-smoker)
68
184cm
571 l/m
-this subject plotted his own profile
time (days)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
peak flow l/m
505
475
505
530
480
480
500
445
460
505
470
580
620
580
time (days)
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
peak flow l/m
580
605
530
540
535
530
525
590
580
625
580
575
590
1.
Draw a chart of time (days) against peak flow (l/m). Join the points with
straight lines.
2.
Add a horizontal line to show PNV.
This patient was diagnosed as having bronchial asthma and emphysema.
started measuring his peak flow before he was prescribed treatment.
He
3.
From his chart, on which day do you think he began his treatment? Why
_________________________________________________________________________________
_________________________________________________________________________________
After a while, the patient stopped taking his medicine.
4.
On which day do you think he stopped? Why have you chosen this day?
_________________________________________________________________________________
_________________________________________________________________________________
He continued to plot his peak profile despite not taking the treatment, and soon
started taking his medicine again.
5.
On which day do you think he re-started his treatment? What do you think
made him return to his treatment?
_________________________________________________________________________________
_________________________________________________________________________________
P4 graph
Peak flow profiles:
• for a 12 year old boy without asthma
x for a 12 year old boy with asthma
P4.4
Example - exercise induced asthma
subject
age
height
PNV
male
10
140cm
318 l/m
PNV = predicted normal value
Look at the two given profiles. The ‘treatment’ for this subject was the use of an
inhaler to relieve the symptoms of asthma.
1.
In the ‘untreated’ profile, what happens to peak flow after exercise?
2.
In the ‘treated’ profile, what happens to peak flow after exercise?
3.
Explain why it is better to give treatment at least 15 minutes before exercise
rather than immediately prior to exercise?
4.
Do these profiles give any hints to asthma sufferers about what to do during
the school day?
time
P5, page 1
Counting breathing rate and pulse rate
Introduction
You are going to observe the difference exercise makes to your breathing and pulse
rates. First, you will need to measure these rates on a volunteer who is at rest. The
volunteer will then exercise and the rates will be measured again.
Safety Note
One person in your group should volunteer for these tests. Do not volunteer if you
have a cold or asthma as these conditions affect your breathing.
TEST 1 - Breathing rate - at rest
Breathing rate can be counted by watching the rise and fall of the chest.
Breathing in and out is counted as one breath not two.
The volunteer can also count his/her own breathing rate as a check for the group.
The volunteer should try to relax and breathe in and out gently.
Practice counting first until you get a reliable result (if everyone in the group counts,
your results should be similar).
Everyone should record the volunteer's breathing rate in the results table (page 2).
TEST 2 - Pulse rate - at rest
A person's pulse can be felt anywhere where a blood vessel crosses over a bone
near the skin surface. Your teacher will suggest where to take the pulse.
Use your fingers, not your thumb, to feel the pulse. The diagram below shows where
to find your pulse in your wrist. Rest your fingers gently against the pulse point.
Everyone can practice counting their own pulse. Only one person will be needed to
count the volunteer's pulse.
Everyone should record the volunteer's pulse rate in the results table (page 2).
P5, page 2
TEST 3 - The effect of exercise
The volunteer will now do some exercise. Your teacher will tell you what exercise
you should do.
The volunteer's breathing and pulse rate both need to be recorded straight after
exercise. Get yourselves organised so that you know who is taking which
measurement. This is very important.
Write the results in the table below so that you can compare breathing and pulse
rate before and after exercise.
Results table
Volunteer's name:
Breathing rate
Pulse rate
(breaths per minute)
(beats per minute)
Before exercise -at rest
After exercise
Q1.
What do your results show?
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
Q2.
What explanation can you give for any differences?
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
_________________________________________________________________________________
P6
Measuring lung volume
SAFETY
The end of the tubing must be sterilised in disinfectant and rinsed in
water before each use.
1
2
3
4
5
Setting up the apparatus
1. Half-fill the bowl with water.
2. Fill the container with water and, if you have the lid, put it on, if not cover the
opening with the palm of your hand.
3. Hold the container upside down with its mouth in the water and then remove the lid
or your hand.
4. Put the tubing into the water and feed through the mouth of the container as shown
in the diagram.
Measuring vital capacity
5. Make sure the container is not resting on the tube. Take a deep breath. Pinch your
nostrils together. Blow out into the tubing for as long and hard as you can.
The air you have breathed out will push an equivalent volume of water out of the
container. The graduations on the container will tell you how much air you have
blown out. This will be an approximate measure of your vital capacity.
Measuring tidal volume
6. For the second part of the investigation, use the air you have blown into the
container. Using a beaker, adjust the water level in the bowl so it is at the same level
as that inside the container. The end of the tubing must be in the air space. (see
diagram).
1
2
3
4
5
7. Pinch your nose. Breathe normally out and in (1 count) through the tubing for five
counts only. Allow the container to move up and down as you breathe.
8. Watch the graduations and you will be able to see how much air you take in and
breathe out. This is your tidal volume.
P7
Comparing inhaled and exhaled air
Using limewater
1. Before using the apparatus, look at the tubes carefully.
Will you take air in from tube A or tube B?
Will you blow air out into tube A or tube B?
2. Breathe gently into the mouthpiece a few times.
3. Now look at the limewater in the tubes again.
What difference do you see?
Breathe GENTLY in and out
limewater
A
B
Making model ribs
3
BACKBONE
D
2
RIB
RIB
RIB
1
1
A
4
20 cm
1
B
3
RIB 2
3
1
4
C
BREASTBONE
2
2
4
10 cm
Making model ribs
Cut out these shapes in card.
1, 2, 3 and 4 are holes.
Using paper fasteners join hole 1 on the
backbone to hole 1 on the rib; hole 2 to hole 2
and so on.
A, B, C and D are holes for the elastic.
2 cm
P8, page 1
1
2
C
A
RIB
RIB
D
3
stretched
elastic
A
C
RIB
RIB
D
B
Position Two
4
Position One
Breastbone
Put the elastic through holes C and D.
The elastic should be stretched.
The elastic is representing the internal intercostal
muscles when these are relaxed and at their longest.
Now make the muscles contract and so get shorter.
What happens to the ribs?
Backbone
Put the elastic through holes A and B.
The elastic should be stretched.
The elastic is representing the external intercostal
muscles when these are relaxed and at their longest.
Now make the muscles contract and so get shorter.
What happens to the ribs?
B
Breastbone
Backbone
P8, page 2
E1
Making a lung mobile
You will need:
•
•
•
•
card
wool or string
pieces of thin garden cane
scissors
Work in a group to make a mobile which will show the right order of breathing
tubes from the mouth or nose to the air-sacs (alveoli).
You could begin your mobile with a piece of card to represent the person's
head.
Cut pieces of card to represent the windpipe (trachea), 2 bronchi and a number
of bronchioles. Write the name of each piece on the card.
You can then cut out shapes (like bunches of grapes) to represent the air-sacs.
Use the wool or string and garden canes to arrange the 'tubes' in the right order,
as shown in the diagram.
Remember:
your mobile only shows the correct order of the breathing tubes not their real sizes.
T
R
A
C
H
E
A
B
R
O
N
C
H
U
S
B
R
O
N
C
H
I
O
L
E
ALVEOLUS ALVEOLUS
B
R
O
N
C
H
U
S
and so on . . .
E2
A letter
Here is a letter you receive from a friend:
At school you have had lessons on breathing and have also learnt some things
about asthma. Write a letter back to your friend giving them some advice about
how to cope with their asthma. Try to reply to some of the things Alex says.
E3 page 1
The treatment of asthma
Many years of research and millions of pounds have gone into the development of
medicines to treat asthma. Indeed money is still being spent on improving the available
products.
The treatment of asthma has been approached in two main ways. One is the relief of
attacks if they begin, the other is the prevention of attacks.
Preventers - these medicines are taken daily and try to make the breathing tubes less
sensitive to triggers. They are usually found in brown inhalers. It is very important to take
these regularly.
Relievers - these medicines are taken if someone suffers an attack. They are usually
found in blue inhalers.
The medicines in relievers and preventers are quite different.
How did scientists produce asthma medicines?
During an asthma attack, the muscles in the breathing tubes contract. This makes the
breathing tubes narrower. Because of this less air will reach the lungs. Research first
began by looking for a substance which would relax the muscles and make the
breathing tubes wider. A substance which does this is called a bronchodilator.
The body produces its own natural bronchodilator - a substance called adrenalin which
is an example of a hormone. You may well have heard of this substance if you watch or
take part in sports. Sports commentators often mention it. Unfortunately, adrenalin is
not a completely suitable substance to use in an asthma attack because it has a
number of unwanted effects on the body. For example, it increases the heart rate and
increases blood pressure. However it’s structure provided a starting point for scientists to
produce a better substance.
Adrenalin is quite a complicated substance but can be shown as a simple diagram.
By changing some of the shapes, a new substance was produced. This substance
widened the breathing tubes but did not have unwanted side effects. The new
substance was called salbutamol and was first marketed in 1969. It is still the most widely
used bronchodilator in the world.
E3 page 2
The treatment of asthma
1.
Explain the difference between preventers and relievers.
2.
In your own words, explain what a bronchodilator medicine does.
3.
Why is adrenalin an unsuitable substance to use in an asthma attack?
4.
Adrenaline is quite a complicated substance. It's structure is based on
a hexagon-like particle.
This particle has 6 places where other groups can be attached.
Salbutamol, like adrenalin, has 3 of these other groups attached to the
hexagon. How many different substances can you make with one
hexagon and 3 extra groups?
For example:
A
A
B
C
Remember that
C
or
or
B
is the same as
A
?
is the same as
A
A
B
B
B
C
C
C
E4 page 1
Asthma inhalers
The special inhalers that asthma sufferers use took over 10 years to develop, at a
cost of more than £50 million. Using an inhaler allows the medicine to act more
quickly than if it was swallowed, as it goes direct to the breathing tubes. It is also
results in smaller amounts of medicine being needed.
The most commonly used inhaler is the metered dose inhaler (MDI). It works on
similar principles to other aerosols but is designed to release exactly the same dose
of medicine each time it is used.
Like other aerosols, a propellant is needed to force the drug out of the canister. The
propellants used in inhalers belong to a group of chemicals called
chlorofluorocarbons (CFCs). CFCs have many properties that make them very good
propellants. However, scientists realised that CFCs could also be very dangerous.
CFCs are very stable substances. This means that they will stay in the atmosphere for
many years and are not broken down. They make their way into the upper
atmosphere called the stratosphere where they damage the ozone layer. Normally
the ozone layer protects us from some of the harmful rays of the sun. The rays are
called ultraviolet radiation. In 1984 scientists of the British Antarctic Survey
discovered a 'hole' in the ozone layer above the Antarctic. This means that more
ultraviolet radiation will be able to reach ground level. Too much ultraviolet light
may lead to skin cancer.
The amount of CFCs released by asthma inhalers is very small. Some
pharmaceutical companies are nevertheless developing new propellants to
replace them. The amount of money spent on this sort of project will virtually equal
the spending on the development of a totally new drug.
Questions
1.
Arrange the following structures in the correct order to show the route which
air takes on its way from outside the body to the site of gas exchange.
•
•
•
•
•
trachea
bronchus
alveoli
nose/mouth
bronchioles
2.
Give two reasons why it is better to inhale asthma drugs rather than swallow
them.
3.
Look at any aerosol container (e.g. polish, hair spray) and write down 2 safety
warnings or precautions mentioned on the container.
4.
Some people think:
"The CFCs in inhalers should be replaced with another propellant"
Explain why you think someone may have this opinion, even though the
amount of CFC's in inhalers is very small.
E4 page 2
5.
Look at the two drawings of the inhaler. Try to describe how the medication
carried in the liquid, is released from the can.
Low boiling liquid containing medication is kept
under pressure in can A.
Can A
Hole C
Plug
Space B
Spring
Hole D
Tube to atmosphere
not in use
after use