3.4 Investigate
How Does the Respiratory System Work?
Read page 86
Vocabulary Chart for Lesson 3.4
Word
Respiratory System
Definition
Organ system that delivers
oxygen to the blood and
removes carbon dioxide ( a
waste ) from blood.
Includes nose, trachea and
lungs.
Trachea
A tube that carries air to the
lungs (windpipe)
Diaphragm
A band of muscle that
regulates pressure in the
chest cavity
Picture
Explore
1. What happens when you breath in and out? Place one hand on your ribs. Place the other hand
just under your ribs. Take 4 or 5 deep breaths. Observe what happens under each of your
hands as you breathe.
2. Answer the following questions.
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a. What do you feel under each of your hands? Example answer: The hand on ribs (over lungs)
felt my chest rise and fall and my hand under ribs felt like it were going up and down.
b. What do your lungs do under your hands when you breathe? So my hand over lungs felt
the lungs expand and contract.
c. Your other hand is just under your ribs. How does this part of you move when you
breathe? The hand under ribs felt as if something is rising up when I exhale and moving
down when I inhale.
Build and Run Model
Build model using the materials and procedure on page 87 of textbook
After you have built the model, run the model and answer the following questions.
1. Pull on the plastic wrap at the bottom of the model. What happens to the balloon inside the
model? How is this like inhaling? Pulling the plastic wrap down increases the volume inside the
model. Air moves from the area of higher pressure outside the model to an area of lower
pressure inside model thru the straw and the balloon fills until the air is equalized. When you
inhale, the diaphragm contracts and moves downward, this increases the volume in your chest
and causes air pressure inside the chest to decrease. Air enters thru your nose, moves down the
trachea to the lungs until pressure is equalized.
2. Push the plastic wrap up at the bottom of the model. What happens to the balloon inside the
model? How is this like exhaling? Pushing the plastic wrap upwards deceases the volume in the
model, air moves out of the balloon thru the straw until the pressure is equalized. When you
exhale, your diaphragm relaxes and moves upward decreasing the volume inside your chest.
This increases the air pressure inside the chest, causing air to move out of your lungs, up the
trachea and leave thru mouth/nose.
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Reflection Questions:
1. For each part of the model,
a. Identify the part of the respiratory system it represents (include nose, trachea, lungs and
diaphragm) Straw is trachea, balloon is the lungs and the plastic wrap is the diaphragm
2. Discuss why the materials used are appropriate. Straw is tube like the trachea, balloon fills with
air like lungs, plastic wrap is flexible like diaphragm.
b. In what ways is the model you built a good model of the respiratory system? The straw is a good
representation of the trachea because it is a tube that connects the outside world to the lungs
inside our body. Balloon is good representation of the lungs because it inflates, is stretchy and
holds air well. The plastic wrap is a good representation of the diaphragm because it is flexible
and moves up and down causing the lungs (balloon) to deflate or inflate.
3. In what ways is the model different from your respiratory system?_Trachea has cartilage rings
that keep it from bending (unlike straw), lungs have alveoli (small balloon like structures) and
are not a single large opening like a balloon, diaphragm plays an active role in assisting the
lungs in inflating and deflating.
4. Use the model to help you make predictions about staying healthy. Using the model, predict
how bacteria or viruses might enter the respiratory system to make you sick. _Microbes might
enter the respiratory system through the mouth or nose with inhaled air. Sometimes you get
microbes on your hands and pass them to your mouth/nose.
Read page 90 in textbook and then answer the following questions .
1. What is the one disease you have learned about so far than impacts the respiratory system
and is caused by bacteria? Some students may know that pneumonia is one respiratory
disease caused by bacteria and it affects the lungs.
2. What is one disease that impacts the respiratory system and is caused by a virus?
The flu (influenza) and colds are respiratory diseases caused by viruses. The cold affects the
nose and trachea.
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