1. Function of the Lungs Primary - to provide a means of gas exchange between environment and body Secondary - maintenance of acid-base balance and as a resevoir for blood

2. Ventilation vs. Diffusion Ventilation - moving air into and out of the lungs –oxygen is moved into the lungs and CO2 is moved out during ventilation Diffusion - random movement of molecules from area of high concentration to low concentration –because O2 concentration is high in the lungs, and low in the blood, O2 diffuses into the blood from the lungs (converse for CO2)

3. Structure Conductive zone - area where no gas exchange occurs, air is simply moved through (eg. trachea, bronchii) Respiratory zone - area where gas exchange does occur (eg. alveoli)

4. Major Organs of the Respiratory System

5. Position of the Pleura and Mediastinum

6. Pathway of Air to Alveoli

7. Alveolus at Microscopic Level

8. Mechanics of Breathing Bulk Flow –movement of air from the environment to the lungs –occurs due to pressure differences at end of system

9. Cont’d Inspiration –major muscle involved is the diaphragm –(diaphragm only skeletal muscle in body considered essential for life) –intrapulmonary pressure reduced below atmospheric –during exercise external intercostals, pectoralis minor, scalene, sternomastoids increase volume of thorax

10. More Expiration –intrapulmonary pressure exceeds atmospheric –passive at rest –during exercise rectus abdominus, internal obliques involved

11. Mechanics of Inspiration and Expiration Pulmonary - ventilation (breathing) and gas exchange in the lungs Cellular - O2 utilization and CO2 production in the tissues

12. Muscles Involved in Respiration