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|C   |Em  |Am  |F


Welcome to system we call respiratory
How we get O2 in and COout is our story
Because every organism, familiar or strange
Has to carry out gas exchange

In all larger species there’s a respiratory surface
Like a gill or a lung that evolved for the purpose
Of providing enough surface area for gas diffusion
In four limbed species lungs are the solution

Breathe, inhale, pull the diaphragm down
Let the air rush in take in oxygen
Exhale, relax, let the air rush out,
Feel the vocal cords vibrate when you talk or shout.
Feel the air in your nose, then the the pharynx, then the glottis,
then the larynx, then the trachea, then left or right bronchus
To the smallest bronchioles to the alveoli
Now, let the air out, breathe a happy sigh!


An oxygen molecule outside your nose
Into the nasal cavity it flows
Passing hairs and cells secreting mucus with each inhalation
Ciliated cells that line this pathway help out with filtration

Then to the back of the mouth the O2 passes,
(You know the mouth’s the other pathway for inhaling gases)
That’s why drinking and laughing can (as everybody knows)
Send the liquid that you drank right out your nose

Next the O2 starts its passage down the windpipe through the glottis
Protected by a flap that’s called the epiglottis
Which covers the windpipe when we swallow
Makes the esophagus the only path that food can follow


So after the back of the mouth, which is also called the pharynx,
Comes the top of the windpipe, the voicebox or the larynx,
The trachea’s next, its many cartilage rings,
Always keep it open, for the air it brings

The trachea ends when it branches into two
Large bronchi, also known as bronchial tubes,
A branching tree forms as the tubes subdivide,
Until they end in hollow sacs called alveoli

Each alveolus has capillaries outside it
Through which red blood cells file right by it
O2 diffuses into each red blood cell
Which becomes oxygenated makes it feel so swell

CO2 oozes in the opposite direction
Moving to the alveolus, diffusing with perfection
CO2’s out;O2’s in
Fill your lungs with oxygen so


Now let’s look at lung ventilation
The way we power inhalation and exhalation
The thoracic (chest) cavity’s a sealed closed chamber
That’s why a chest wound carries so much danger

So just below the rib cage in a woman or man
Is a sheet of tissue called the diaphragm
Muscles below the diaphragm can pull it down
This powers ventilation let me show you how

Inhalation pulls the diaphragm down which increases
Chest cavity volume so the pressure decreases;
The higher pressure air outside the lungs flows in
The lungs inflate that’s inhalation

To exhale you relax, diaphragm arches up
Sends chest cavity pressure up
So as chest cavity volume’s decreased
The gases in your lungs have to be released so