ALL ABOUT LUNGS
Today you will embark on a journey through 5 activities designed to assist you to develop your
understanding of the structure and function of the mammalian respiratory system
Activity 1: Investigating the lungs
Aim: to examine the structure of the trachea and lungs and relate this to lung function.
Safety:
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Tie hair back, wear safety glasses, apron, and gloves.
Be careful with dissecting equipment; always cut away from yourself.
Do not inhale air from the lungs.
Disinfect work area and equipment after use and wast hands thoroughly with soap and
water.
Examine a pluck:
1. a) Observe and describe the look, feel and colour of the lungs
They feel spongy and look shiny and cream/pink in colour
b) Lungs are moist why do they need to be moist?
They need to be moist to enable gases to dissolve into a film of liquid so that they can cross
membranes of cells forming the alveolus .
2. Identify the trachea and explore the texture of its wall
a) Describe the trachea either in words or as an annotated diagram.
A flexible tube with rings of C shaped cartilage along its length
b) The function of the trachea is to enable air to travel from the nose to the lungs and back.
It also needs to be flexible and bendable. What features can you identify that suit it to its
function?
The C shape rings of cartilage help to keep the airway open/help to prevent them from
collapsing (or expanding too much) when pressures change during inhalation and
exhalation. This allows gas to be draw into and forced out of the lungs, at the same time
allowing flexibility due to its pliable nature.
3. Explore the tubes that enter the lungs and describe how they divide either in words or as an
annotated diagram.
The trachea divides into two bronchi; secondary bronchi branch from each bronchus and
progressively small tubes (different types of bronchioles) branch from these ending in the
respiratory bronchioles which lead to alveolar sacs. As the branching airtube in the lungs
get smaller and smaller, cartilage decreases, epithelial cells become thinner, cilia become
less numerous until there are none at all, and mucus production declines.
4. If the heart it present examine and describe its position with respect to the lungs.
The heart is in between the lungs , with its apex toward the left
5. Examine the blood vessels leading from the heart to the lungs and vice versa. Describe
these vessels eg. how long are they? what do they feel like?
The pulmonary artery and pulmonary vein are very short blood vessels; the lungs are very
close to the heart so blood doesn’t need to be transported very far. They are quite tough
and fairly wide.
6. Find any remnant of the diaphragm and describe its location relative to the lungs
It is located beneath the lungs. (it forms the bottom of the thoracic cavity)
7. Examine the microscopic image of lung tissue. Describe the tissue.
Some air tubes are evident(bronchioles)
Thin walled compartments (alveoli) and empty spaces
Terminal portion of respiratory tree Elastic van Gieson. 40x
T=terminal bronchioles
R=resp. bronchioles
A=alveoli
AD=alveolar ducts
AS=alveolar sacs
Burkitt, Young, Heath (1993) Wheater's Functional
Histology 3rd Ed. Fig. 12.12, p. 228
8. Cut a piece of lung tissue. Draw a sketch showing the cross section of the cut you made.
You can see circles which are transverse cuts through air tubes of varying sizes
9. Place the cut piece of tissue it into a beaker of water. What happens? Explain this
observation.
Lung tissue floats when placed in water while other tissue(heart, liver) of a similar size and
surface area do not. The large amount of air in this tissue gives it a low density and thus is
very buoyant.
10. When your teacher inflated a portion of the sheets lung how did the appearance and feel of
the tissue change? Give a reason for any change noted.
Its colour became a lot paler (it was more cream than pink) This is because the blood in
the blood vessels is spread out over a greater area, causing dilution of the colour. The feel
of the organ is quite strange; firm but cushiony.
Activity 2: Respiratory Anatomy
1) Label the following features on the diagrams below:
Diagram A: Trachea, rings of cartilage, bronchus, secondary bronchus, Bronchioles, Alveolus, larynx,
Diagram B: rib, intercostals muscles, diaphragm, pharynx, epiglottis
Diagram A
larynx
Bronchus(right)
Diagram B
Ring of cartilage
trachea
pharynx
epiglottis
Bronchus(left)
Secondary bronchus
Intercostal muscles
rib
bronchioles
alveolus
diaphragm
2. Examine Diagram A. Use an analogy to describe the internal structure of the lungs.
An upside down tree
3. Example diagram B. Describe two differences between the left lung and the right lung
Size of lung is smaller overall on the left hand size than right
Fewer lobes on the left hand side than on the right
Left lung is lighter than the right
4. List the structures in the order in which air passes them as in travels from nose to lungs
Nose, pharynx, larynx, trachea, bronchus, (secondary bronchus), bronchioles, (alveolar
sacs), alveolus. If you missed the things in bracket don’t worry about these. These are
finer detail.
5. Match the correct term to the description below
Trachea, alveolus, bronchi, nasal cavity, bronchioles, pharynx, expiration, epliglottis, diaphragm
Smallest respiratory passageways: bronchioles
Branches from the trachea into each lung: bronchi
Windpipe: trachea
Where gas exchange takes place: alveolus
Stops food passing down the trachea: epiglottis
The movement of air out of the lungs: expiration
The muscle at the base of the thoracic cavity that is involved in drawing aim into and pushing air out
of the lungs: diaphragm
Activity 3: Stimulating Breathing using the model lung
Examine the model lung:
1. What does the tubing in the mouth of the bell jar represent? trachea
b) How could you making this tubing more accurately represent this structure? Encircle it
with flexible c shaped rings
2. a)What organ is represented by the balloons? lungs
b) Do the balloons accurately represent the real organ? No; the balloons are two sacks rather
than the millions of tiny sacs like real lungs have. They provide a much smaller gas
exchange surface than real lungs.
3. What does the bottle represent? The wall of the thoracic cavity.(or rib cage and intercostal
muscles)
4. What does the plastic sheeting at the bottom of the bell jar represent diaphragm
5. Investigate the effect of moving the plastic sheeting up and down. Complete the following
statements in relation to this motion
 When the plastic sheeting is pulled down, the balloons inflate. This is because this
results in a decrease in air pressure in the bell jar causing air to be drawn into the
balloons.
 When the plastic sheeting is pushed upwards the balloons deflate. This is because
this causes an increase in air pressure in the bell jar forcing air out of the balloons.
Applying this understanding to human lung function
6. If a person was stabbed with a knife in the chest and the wall of the thoracic cavity was
punctured what effect might this have on inhalation and exhalation? Explain.
If would make inhalation and exhalation comparatively ineffective.(1) The pressure changes that
result in inhalation(air being drawn into the lungs) and exhalation (air being force out of the lungs)
would not be able to be achieved(1) due to air leaving or entering via the opening created by the
stabbing(not to mention bleeding etc)(1) An air tight thoracic cavity is need for effective inhalation
and exhalation.
Activity 4: Asthma
Introduction
Australia has one of the highest rates of asthma sufferers in the world. Asthma-related
illnesses are estimated to cost taxpayers $760 million a year. Each year there are around 800
related deaths. Asthma is a non-contagious condition that cannot be cured, however in
most cases it can be successfully managed with medication such as ventolin.
An asthma attack happens when something irritates the sufferer’s respiration system
triggering a series of events that make it difficult for the structures within the lungs to get
oxygen into the bloodstream and carbon dioxide out. An asthma attack begins by striking at
the bronchi and the bronchiole. In normal lungs, air from the bronchioles moves into tiny air
sacs called alveoli. Oxygen moves from these sacs into the bloodstream through tiny blood
vessels called capillaries. At the same time, carbon dioxide is removed from the blood and
exhaled from the body. An asthma attack causes the muscles surrounding the lungs’ airways
to tighten. These airways become inflamed and swollen, so that breathing becomes much
more difficult. Finally the lungs begin to produce mucus that clogs the airways even more.
Asthma victims often make wheezing sounds and cough as they struggle to breathe and
clear out the excess mucus. For someone with asthma breathing out or exhaling is as hard
as breathing in.
Breath test
In this activity you will create a simple model of the respiratory system. Not only will you
measure the effects of narrowed airway channels, you will experience it as well.
Materials
 Construction paper scissors and tape
 Round balloons
 Plastic drinking straws (0.6 cm diameter) cut to 15cm lengths
 Rubber bands
 Stopwatch
 Honey or maple syrup
Method
If you suffer from asthma you should not participate in blowing up the balloon in this activity
1. Use a 2.5 cm strip of paper and tape to make a ring 20cm in diameter
2. One group member acts as time keeper, another holds the paper measuring ring and a
third blows up a balloon until it reaches a diameter of 20cm, as measured by the paper
ring. The time keeper uses a stop watch to measure the time taken (to the nearest
second) to inflate the balloon and the result is recorded in the table.
3. When the inflation is complete, pinch the balloon shut, reset the stop watch and then
time how long it takes for the balloon to completely deflate. Record your result.
4. Repeat steps 2 and 3 two more times and average the results for the three trials
5. Insert a 15cm length of drinking straw about 2.5cm into the opening of the balloon and
secure it with a rubber band.
6. Repeat step 2 and 4
7. Place 2 squirts of honey or maple syrup into the balloon through the straw. Gently
squeeze the balloon so that the entire length of the straw is filled with honey(or syrup)
8. Repeat step 2-4
Results
Table 1: Time taken to inflate and deflate a balloon under varying conditions
“Lung” condition
Trial 1
Inflate
Deflate
Time (seconds)
Trial 2
Inflate
Deflate
Trial 3
Inflate
Deflate
Average
Time(sec)
Inflate
Deflate
Balloon
Balloon with straw
Balloon with straw
and honey
Questions
1. In our model the three balloons represent different conditions in the human respiratory
system. What are they? Explain.(3)
Normal balloon: normal lung
Balloon with straw: bronchi and bronchioles become constricted and narrow due to inflammation
and muscle tightening that occurs due to asthma
Balloon with straw filled with honey: mucus production as a result of the asthma attack
2. How did narrowing the passageway and adding a thick sticky substance affect your ability to
blow up the balloon? Quote data in your answer (2)
Decrease ability to inflate balloon. It took more time to inflate the balloon.(quote data)
3. How did narrowing the passageway and adding a thick sticky substance affect you ability to
deflate the balloon? Quote data in your answer (2)
Decrease ability to deflate balloon. It took more time to deflate the balloon.(quote data)
4. Using you data is the inflation rate or the deflation rate the most affected in asthmatics? (2)
The (straws) narrow tubes and (syrup) mucus affect the deflation rate more than the inflation rate.
Getting air out of the lungs is more of a problem for asthmatics than getting air in.
5. Suggest how asthma medicines such as ventolin treat an asthmatic attack?(2)
Ventolin should relax the smooth muscle surrounding the bronchi and bronchioles,
dilating these tubes and provided a wider tube trough which air can pass. This makes it
easier to move air into and out of the lungs.
6. What effect would you expect asthma to have on breathing rates? Explain(2)
Would expect breathing rate to increase.(but the depth to be shallower)(1) As it is harder to get
air out of the lungs, it is hard to remove Carbon dioxide and increased levels of carbon dioxide in
the blood would cause and increase in breathing rate. (1)
Activity 5: Effect of Activity on breathing rate: Homework
A Student conducted the following experiment
Aim: To determine the effect of activity on breathing rate
Hypothesis: That breathing rate will increase as rigor of exercise increases
1. Sit at rest for 1 min
2. Take your breathing rate for 30 seconds and double this to obtain you breathing rate
breaths/min
3. Record and graph your result
4. Complete mild exercise such as walking for 2 minutes complete steps 2 and 3 as above
5. Sit and rest for 1 min
6. Complete rigorous exercise(quick star jumps or running) for 2 minutes and complete steps 2
and 3 as above
7. If time permits wait for your breathing rate to return to its resting level and repeat steps 1-6
then average results.
The results obtained are shown in the table below
Result
Table: Effect of Activity level on breathing rate
Level of
Activity
Rest
Mild exercise
Moderate
exercise
Breathing Rate
(breaths/min)
Trial 1 Trial 2 Average
16
17
16.5
30
28
29
45
40
42.5
Graph the results
Effect of Activity level on average breathing rate
Questions
1. In this experiment
 What is the IV: intensity of exercise
 What is the DV: breathing rate
2. How did your breathing rate change with increased activity (2)
Breathing rate increased as activity level increased. Second mark is for quoting data to show this.
3. Breathing rate in humans is controlled by specialized centres in the brainstem, which
automatically regulate the rate and depth of breathing depending on the body’s needs
at any time. Breathing rate is altered in response to the level of carbon dioxide in the
blood. Given this information explain the reason for this change in breathing rate with
exercise.(4)
Need
Link between exercise and ATP,
Link between ATP and cellular respiration
Link between cellular respiration and carbon dioxide production
Link between increase carbon dioxide in blood and breathing rate
For example:
Musclular work during exercise requires ATP. ATP is formed in cells by the process of
cellular respiration.(1) Cellular respiration produces carbon dioxide as a product.(1)
As exercise intensity increases, the amount of ATP required increases, increasing the rate
of cellular respiration and the consequential rate of carbon dioxide production. (1)Thus
breathing rate and depth increase during exercise in response to the elevated levels of
carbon dioxide that are produced.(1)
(As the carbon dioxide level in the blood is elevated this is detected and a message is sent
to effectors to increase the breathing rate)
4. a) As well as a change in breathing rate, what other functional changes occur in the body
during exercise?
For example
3a)
3b)
Increase in heart rate to transport gases
to pick up carbon dioxide efficiently from
quickly enough to meet requirements
respiring cells and to deliver oxygen
required to respiring cells. This enables
respiration and ATP production to be
sustained.
Increase in volume of perspiration
released
Face become flushed due to dilation of
surface arterials
increase rate of evaporative cooling
this increases volume of blood traveling
close to skin and thus increase heat loss
across skin.
b) Give a brief reason for each change noted in 3a)