2 functions of the
Respiratory System
1. Moves oxygen from the
outside environment into the
body.
2. Removes carbon dioxide and
water from the body (aka
waste).
Human Lungs
NOT Hollow Balloons but, A Spongy
Organ
The respiratory system includes:
nasal passages
pharynx
larynx
trachea
bronchi and bronchioles
alveoli
The Path of Air
1. Air first enters the Nose or Mouth –
 Air is moistened and heated before
going into the trachea.
 Cilia and mucus, in the nose, trap dirt
from the air.
Cilia – cells with hair like extensions.
Mucus – sticky material, keeps nose from
drying out. Traps dust particles.
Cilia push the mucus to the back of
your throat and you swallow it!!
**On average, you swallow a pint of
mucus per day (milk carton in
cafeteria)
The Path of Air cont.
2. Air moves to the Pharynx – (the
throat)
3. Into the Larynx (voice box)
Epiglottis - flap of tissue that
covers the opening of the larynx
when you are eating. Also protects
from sinus drainage.
If food goes down the larynx you
________.
The Path of Air cont.
4. Air moves into the
trachea (aka the
windpipe) a 4 inch long
tube that moves air
into your lungs.
The walls of the trachea have
rings of cartilage to protect it
and prevent it from collapsing.
The trachea splits into 2
bronchi.
The Path of Air (Cont.)
5. Bronchi (tubes) – You have 2 bronchi. One
leads into your right lung and one into your
left lung.
Each bronchus (singular) leads air into the
lungs and divides into smaller and smaller
tubes, called bronchioles.
**Think of how a tree trunk divides into
smaller and smaller branches.
6. The last stop for air is in the
Alveoli – grape-like structures
at the end of the bronchioles.
Capillaries, very tiny blood vessels,
surround each alveoli cluster so the
blood can pick up large amounts of
oxygen.
Breathing vs. Respiration
Breathing – Movement of air in and
out of the lungs.
Respiration – The release of energy
that takes place inside of cells.
Oxygen and sugar are used by the
cell to generate energy for your
body to use, for growth and
function.
Diaphragm – a large dome-shaped
MUSCLE, just under the lungs, that
moves to inflate the lungs with air.
This is the muscle that contracts and
relaxes to fill the lungs with air! The
brainstem controls this muscle.
 The
left lung is a little smaller than the
right lung because it shares space in the
left side of the chest with the heart.