1. One of the great exchange systems in the body
Gas exchange
One of the great exchange systems in the body
© 2016 Paul Billiet ODWS

2. Breathing ≠ Respiration
Ventilation is the pumping of air into and out of the alveoli of the lungs Gas exchange is the exchange of CO2 and O2 between the air in the alveoli and the blood in the capillaries Cell respiration is the process that consumes the O2 and produces the CO2. It takes place in all the cells.
© 2016 Paul Billiet ODWS

3. The exchange surface 70m2 of air meets 60m2 of blood
© 2016 Paul Billiet ODWS

4. Capillaries Capillary network of a rat lung © 2016 Paul Billiet ODWS
© 2016 Paul Billiet ODWS

5. Alveoli (300 million) © 2016 Paul Billiet ODWS
© 2016 Paul Billiet ODWS

6. Alveolar wall Type 1 & type 2 pneumocytes © 2016 Paul Billiet ODWS
Type 1 & type 2 pneumocytes
© 2016 Paul Billiet ODWS

7. Adaptations Large surface area 70m2
Thin barrier to diffusion 0.4µm (type 1 pneumocytes)
Constant renewal of air and blood, maintains concentration gradient
Surfactant stops sides sticking (type 2 pneumocytes).
warriors.warren.k12.il.us/dburke/alveoli2.jpg
© 2016 Paul Billiet ODWS

8. The ventilation system
Intercostal muscles
Trachea
Bronchus
Bronchioles
Diaphragm
Heart
Lung
Ribs
Larynx
Cartilage rings
© 2016 Paul Billiet ODWS

9. Ventilation © 2016 Paul Billiet ODWS
© 2016 Paul Billiet ODWS

10. Ventilation - Inhaling
The diaphragm muscles contract and the diaphragm is pulled down
The external intercostals contract and the ribs rise
The lungs expand with the thorax and the lung volume increases
The pressure in the thorax falls, air is drawn into the lungs.
© 2016 Paul Billiet ODWS

11. Ventilation - Exhaling
The diaphragm muscle relax and the elastic lung tissue retracts
The external intercostals relax and the ribs fall
The lung volume diminishes and air leaves the lungs
Air may be forced out by the internal intercostals and abdominal muscles contracting to pull the ribs down.
© 2016 Paul Billiet ODWS