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Gasping For Air – 50 Informal Points
Introduction
Why can the human body last for only a few minutes without oxygen, yet can survive for days without food or
water? Remember the Rules of Three that we discussed at the beginning of Unit 3. The body can last three
minutes without air; yet it can last three days without water and three weeks without food! From these time
limits it is easy to see that oxygen must be very important and that the body needs a near constant supply.
What does oxygen provide to the body that is so important for survival?
Cells need energy to function. They obtain this energy from the energy storing molecule ATP. Think back to
what you have already learned about ATP. It is formed by combining the nucleoside adenosine with three high
energy phosphate groups. In order for ATP to be produced, oxygen must be available. Without oxygen, the
addition of the third phosphate group does not occur, and ATP is consequently not produced. Without ATP, the
body’s cells do not have a source of energy and will die once a cell’s ATP reserves are used up.
The body’s source of oxygen is the air in the atmosphere. Getting oxygen from the air to each cell in the body
requires a complex and coordinated effort from the respiratory and cardiovascular systems. Every minute
these systems work together to take in oxygen the body needs and get rid of the waste gases produced.
In this activity, you will meet a young girl who is struggling to breathe. As you work to diagnose her, you will
investigate the structure of the respiratory system and consider what happens in the body when low levels of
oxygen cause a person to gasp for even a simple breath.
Procedure
Part I: Meet Melissa
Melissa Martin, age 11, is finding it harder and harder to catch her breath during her normal activities. It is your job
to analyze Melissa’s symptoms, research a diagnosis, and provide recommendations for treatment and control.
1. Obtain a Medical History – Visit #1 Resource Sheet.
2. Read the case notes provided for your patient. Highlight or underline any symptoms or relevant history you
feel will be helpful in making a diagnosis. Research information from the medical history and physical
exam. Take notes in the space below. You must research a minimum of four key points.
Symptoms of asthma:

Coughing

Wheezing

Shortness of Breath

Chest tightness, Pain or Pressure

Breathing in certain, irritating substances, can trigger the airways to narrow, making it hard for air to
flow in and out of the lungs
3. Brainstorm what might be going wrong Melissa and come up with an explanation of Melissa’s symptoms.
Record your ideas in the space below.
Asthma  Melissa is not getting the oxygen she needs
4. Add your explanation to the appropriate section on the Medical History Resource Sheet.
5. Research next steps for Melissa Martin. How can you confirm the diagnosis and begin to treat your
patient? Discuss in the space below.
6. Record any ideas in the Recommendations section of the Medical History document.
Part II: Inside the Respiratory System
7. Begin to investigate the structure and function of the respiratory system. Go to the Go to the NIH National
Heart, Lung, and Blood Institute, accessible at http://www.nhlbi.nih.gov/health/healthtopics/topics/hlw/system
8. Read the introduction titled The Breath of Life in the mini window.
9. Select Lung Anatomy in the mini window. Click on either the lung diagram or the names of structures to
see more information about the lobes, trachea, diaphragm, bronchi, and bronchioles.
10. Sketch a diagram of the respiratory system on a blank Human Body System Organizer. Label each of the
components and write a brief description of each component’s function.
11. Select the Alveoli tab in the lower left corner. The diagram and names of structures should change to
represent the smallest structures associated with the lungs. Again click on either the diagram or the names
of the structures to see more information about the alveoli, bronchioles, and blood vessels. In the space
below, describe the relationship between the bronchioles, alveoli, and blood vessels. Add a drawing or
sketch if desired.
The body takes in oxygen through inhalation through the mouth or nose. The air then passes through the
pharynx (first part of throat), larynx (voice box), trachea (windpipe), bronchi, bronchioles, alveoli, and
capillaries. The alveoli are the air sacs that create lots of surface area so that oxygen absorption is
maximized; they are surrounded by capillaries (tiniest of blood vessels) so that O 2 may diffuse across the
alveolar and capillary membranes so that oxygen can easily move from lungs to blood. This is where the
respiratory system meets the circulatory system. The alveolar and capillary membranes are very thin so
that this diffusion may happen very fast.
Similarly, carbon dioxide (CO2), the waste product of cells, diffuses across the capillary membranes and then
the alveolar membranes so that it may be exhaled by the lungs.
12. Select Lung Functions. Complete the interactive demonstration of lung function. Watch carefully what is
happening in the alveoli. Make sure to continue through the entire animation.
13. View the Anatomy of Breathing animation available at http://teiteachers.org/sites/teachhealthk12/files/activity/downloads/AnatomyofBreathing3.swf. Watch gas exchange on inhale and exhale, also
paying attention to the role of muscles in respiration. Take notes about the process in the space below.
The diaphragm is the muscle responsible for breathing. When the diaphragm contracts the lungs expand,
causing inhalation (or inspiration.) When the diaphragm relaxes the lungs contract, causing exhalation (or
expiration.)
14. Click on Take a Closer Look to examine gas exchange at the level of the alveoli.
15. Visit the American Lung Association site on asthma available at http://www.lung.org/lung-health-anddiseases/lung-disease-lookup/asthma/asthma-education-advocacy/asthma-basics.html. Define
asthma in the space below.
Asthma – A chronic lung disease that makes it harder to move air in and out of the lungs. It can start at any age.
16. Watch the What is Asthma? video to explore how asthma impacts normal functioning of the lungs. Take
notes in the space below.
Asthma is a disease that affects the airways of your lungs. With asthma, your airways' lining tends to always be in a
hypersensitive state characterized by redness and swelling (inflammation). It's similar to how your skin becomes
red, irritated and sensitive after a sunburn. This hypersensitive state makes the airways react to things that you are
exposed to every day, or asthma "triggers." A trigger could be the common cold, stress, changes in the weather, or
things in the environment, such as dust, chemicals, smoke and pet dander.
Asthma Flare-Ups: When you experience a trigger, the insides of your airways swell even more. This narrows the
space for air to move in and out of the lungs. The muscles that wrap around your airways also can tighten, making
breathing even harder. When that happens, it's called an asthma flare-up, asthma episode or asthma "attack."
After an asthma flare-up, you probably will feel tired. You're also at greater risk of having another flare-up for
several days after an episode. For the days following a flare-up, be sure to: Avoid your asthma triggers, Monitor
your symptoms or check you airways using a peak flow meter
Airway Remodeling: Poor asthma management can lead to airway remodeling. Airway remodeling is a serious
condition that happens when asthma is untreated or poorly managed. The lungs become scarred, asthma
medicines do not work as well and less air is able to move through your airways. Airway remodeling does not have
to happen. Work with a healthcare professional to minimize asthma flare-ups and find a treatment plan that works
for you.
17. View the Kids Health video What Happens During an Asthma Flare-up available at
http://kidshealth.org/teen/videos/flare_up_vd.html.
Part III: Follow-up Visit
18. Obtain a Medical History – Visit #2 Resource Sheet.
19. Read the updates to the Case History.
20. Review Melissa’s Peak Flow Chart. Note that average (or normal) peak flow for a patient of Melissa’s size
is 267. The chart below describes the classification of peak flow values.
Normal Peak Flow Values
% of Normal Peak Flow:
Meaning:
Classification:
80% - 100%
All is fine
Green Zone
50% - 80%
Caution
Yellow Zone
Less than 50%
Medical Alert
Red Zone
21. Calculate the value ranges that relate to the Green, Yellow, and Red zones for Melissa. List the values on
the Medical History form under the graph and use colored pencils or markers to shade in the associated
ranges of the peak flow chart.
22. Analyze Melissa’s peak flow graph as well as her descriptions of her symptoms and activities on each day.
Describe conclusions about her condition on the Explanation of Results section of the Medical History
Resource Sheet.
23. Read the Recommendations section of the report.
Conclusion Questions
1. The walls of the alveoli in the lungs are incredibly thin. Explain how this structure is related to function in
the body.
The walls must be very thin for gases, such as O2 and CO2, to quickly and efficiently diffuse from alveoli to
capillary and vice versa. O2 is essential for brain function and must be readily obtained
2. Remember what you learned about diffusion in PBS or another science class. Use the principles of
diffusion to explain why oxygen molecules in the tissues of the lung go into the blood, and then in other
tissues the oxygen molecules leave the blood.
O2 diffuses into the blood from the alveoli to be carried via the circulatory system to all cells of the body. Every
cell in the human body needs oxygen to perform aerobic respiration in the mitochondria. A waste
byproduct of cell respiration is CO2. Carbon dioxide passes by diffusion from the cell into the capillaries
where it enters the blood stream and travels via the circulatory system to the alveoli and lungs where it can
be exhaled.
3. What changes inside the airways in the lungs lead to an asthma attack?
This is the same answer as in #16:
Asthma is a disease that affects the airways of your lungs. With asthma, your airways' lining tends to always be in a
hypersensitive state characterized by redness and swelling (inflammation). It's similar to how your skin becomes
red, irritated and sensitive after a sunburn. This hypersensitive state makes the airways react to things that you are
exposed to every day, or asthma "triggers." A trigger could be the common cold, stress, changes in the weather, or
things in the environment, such as dust, chemicals, smoke and pet dander.
Asthma Flare-Ups: When you experience a trigger, the insides of your airways swell even more. This narrows the
space for air to move in and out of the lungs. The muscles that wrap around your airways also can tighten, making
breathing even harder. When that happens, it's called an asthma flare-up, asthma episode or asthma "attack."
After an asthma flare-up, you probably will feel tired. You're also at greater risk of having another flare-up for
several days after an episode. For the days following a flare-up, be sure to: Avoid your asthma triggers, Monitor
your symptoms or check you airways using a peak flow meter
Airway Remodeling: Poor asthma management can lead to airway remodeling. Airway remodeling is a serious
condition that happens when asthma is untreated or poorly managed. The lungs become scarred, asthma
medicines do not work as well and less air is able to move through your airways. Airway remodeling does not have
to happen. Work with a healthcare professional to minimize asthma flare-ups and find a treatment plan that works
for you.
4. Explain how monitoring Melissa’s response to medication during wheezing events can help in making a
clinical diagnosis of asthma.
If she improves on the medicine (such as inhaler) then the symptoms and condition have been treated
indicating asthma most likely is the culprit.
5. Note that Melissa’s exam indicates a pulse ox value of 91%. What is this value and how can it be used to
monitor overall health?
Pulse ox value measures how saturated your red blood cells (erythrocytes) are with oxygen. A healthy value is
100%. The lower the value the unhealthier the individual as cells are not receiving the oxygen they need
to function. This often indicates a respiratory or circulatory disease.
6. What environmental conditions might cause damage to the alveolar sacs, and what would be the
consequences of that damage?
Airway Remodeling: Poor asthma management can lead to airway remodeling. Airway remodeling
is a serious condition that happens when asthma is untreated or poorly managed. The lungs
become scarred, asthma medicines do not work as well and less air is able to move through your
airways. Airway remodeling does not have to happen. Work with a healthcare professional to
minimize asthma flare-ups and find a treatment plan that works for you.
7. Describe how the muscular system is interconnected to the respiratory system. What role do muscles play
in an asthma attack?
The key to an asthma attack is the diaphragm. This contracts normally when breathing in and then relaxes to allow
expiration. With an asthma condition, the diaphragm may be partly in contraction, hence the wheeze of an asthmatic.
If a trigger, such as cold or illness, or an allergy is detected, the diaphragm seems to contract more and more thus
allowing the asthmatic to breathe in, but not to breathe out. This connects the respiratory system to the
muscular system.
8. Describe the interaction between the cardiovascular system and the respiratory system. Make sure to
include the words hemoglobin and carbon dioxide as well as relevant anatomy you have learned in this
lesson.
Inhale oxygen via nasal cavity or mouth  Pharynx  larynx  trachea  bronchi  bronchioles  alveoli 
capillaries  bloodstream  O2 specifically binds to the hemoglobin protein in the red blood cells 
travels via the circulatory system to the body cells where it diffuses out of the capillary and into the cell 
the cell has CO2 waste that diffuses the opposite direction from the cell into the capillary  the carbon
dioxide travels through the circulatory system to be unloaded via diffusion in the lungs  CO2 is exhaled