1. The Respiratory System
Body Systems Unit
The Respiratory System

2. Catalyst Do all living organisms need to breathe? Why do we breathe?
What are TWO things that muscles need to function properly?

3. Objective
Scientists will be able to describe the basic structure of the human respiratory system and how it helps all the body systems function.

4. Observation
With a partner, watch each other taking deep breathes for 1 minute.
Write down what observations you noticed about how your partner was breathing.
When your partner was breathing in, what did you notice? How about when breathing out?
Why did their body move the way it did when they were breathing?

5. How does the air get in?
The DIAPHRAGM is a large muscle that is located below your lungs.
The lungs are surrounded by your ribs.
As this muscle CONTRACTS (pulls down) air rushes into the lungs.
Think of it this way:
As the diaphragm pulls down, there’s MORE room to fill with air. The air gets REALLY REALLY excited and rushes into the larger area. As the diaphragm relaxes, there is less room and so all of the air particles leave.

6. Experience Breathing
Breathe in and hold your breath a moment. What do you feel in your chest/ribs area?
Breathe out slowly. Now what do you feel?

7. Breathing with our body!
- When we INHALE, or breathe in, the rib muscles contract lifting the chest upwards and the diaphragm MOVES DOWN to make space for the lungs to expand and fill with air.
- When we EXHALE, or breathe out, the rib muscles relax lowering the chest and the moving the diaphragm BACK UP so the chest cavity is smaller and squeezes out the carbon dioxide and water.

8. ✔ Check For Understanding ✔
In your own words, describe what the diaphragm does in reference to breathing.

9. The journey of air…
As your diaphragm contracts, the air particles realize that there is more room inside your lungs and they decide to rush in.
The front door, or first structures they will pass are the NOSE and MOUTH.

10. The journey of air…
Next the air must walk down the hallway past the PHARYNX and LARYNX.
These structures are located at the back of the mouth and throat.
The LARYNX is the VOICE BOX and entrance into the TRACHEA.

11. The journey of air…
FINALLY it can enter into a long rigid tube called the TRACHEA.
The TRACHEA
Connects to two more
Tubes called BRONCHI.

12. ✔ Check For Understanding ✔
What is the muscle that CONTRACTS to make room for more air to enter into the lung?
Which is the correct pathway for air to travel into the lung?
Mouth/nosebronchilarynxpharynxtrachea
Mouth/nosepharynxlarynxtracheabronchi
Mouth/nosetracheabronchilarynxpharynx

13. The journey of air – into the body
The BRONCHI divert the air to both lungs.

14. The journey of air – into the body
Once the air has reached the inside of the lung, they encounter sac-like structures called ALVEOLI.
These particles move the oxygen into the bloodstream (which is why our blood turns RED!)

15. The Total Journey Air enters in the mouth and nose
Diaphragm Contracts
Air enters the bronchi
Air enters the Trachea
Air passes the Pharynx
Air enters the alveoli
Air passes the Larynx