Lesson 3 How Lungs are Protected and How we Breathe
Protecting your lungs
The following structures are there to protect your lungs from physical
damage:
1.. Muscle.
2.. Fat.
3.. Ribs.
4.. Sternum or chest bone.
5.. Spine column.
6.. Colar bone.
7.. Shoulder blade.
8.. Diaphragm (bottom of lungs).
9.. Pleura membranes:
* 2 of them.
A.. Visceral pleura – inside sac that sticks directly onto lung surface.
(stops germs from getting into the lungs.)
B.. Parietal pleura – stuck directly to the inside of the chest wall/diaphragm.
Functions:
 Lubricate between layers while ribs move.
 Air tights with NO gases in there; only water is the lubricant.
How we breathe
To increase the volume of lungs:
A.. The rib cage must move up and outwards. (Muscles make the ribs
move).
B.. The diaphragm moves down. It is a muscle that is 1 inch thick.
As the ribs move up and out:
 The pleura move up and out.
 The lungs move up and out.
 The alveoli (sacs) stretch open.
As the diaphragm moves down:
 The pleura move down.
 The lungs move down.
 The alveioli open up.
RESULT:
As we stretch everything open, lung volume increases which causes air
pressure to decrease. HIGHER air pressure OUTSIDE your body flows into
LOW air pressure IN. your lungs until the pressures are equal.
OUT BREATH:
Exact opposite: air moves from HIGH air pressure INSIDE lungs to LOW air
pressure OUTSIDE body.
Breathe in = INSPIRATION.
Breathe out = EXPIRATION.