1. Breathing

2. Breathing/Ventilation
Moving air into and out of the lungs
Thoracic cavity is like a sealed container
The diaphragm can change the volume, which in turn affects the air pressure

3. Inspiration As you breathe in: The inspired air expands your
Diaphragm contracts (moves down)
Intercostal muscles contract (expands rib cage)
Abdominal muscles relax (allows compression of the abdomen)
The inspired air expands your
thoracic cavity, reducing the
air pressure within the alveoli
because P  as V 
Air travels from high pressure
area (mouth and nose) to low
pressure area (alveoli)

4. Expiration As you breathe out: Your lung volume decreases
Diaphragm relaxes (moves up)
Intercostal muscles relax (condenses rib cage)
Abdominal muscles contract (pushing up against diaphragm)
Your lung volume decreases
causing higher air pressure
in the alveoli
Air travels from high pressure
area (alveoli) to low pressure
area (nose and mouth)

5. Lung Capacity
p. 263

6. What are some factors affecting lung capacity?
Volume in Males
(mL)
Volume in Females
Total Lung Capacity
5900
4400
Vital Capacity
Inspiratory Reserve
Tidal Volume (rest)
Expiratory Reserve
4700
3000
500
1200
3400
2100
1000
Residual Volume