1. Copyright © 2006 by Elsevier, Inc. Mechanics of Respiration Inspiration Resting –Diaphragm Active –Diaphragm –External intercostal muscles Diaphragm

2. Copyright © 2006 by Elsevier, Inc. Mechanics of Respiration Inspiration Active –Diaphragm –external intercostals Spine External Intercostals ribs

3. Copyright © 2006 by Elsevier, Inc. Mechanics of Respiration Expiration Resting passive process elastic properties of lung Active Abdominals decrease chest volumes Active exhalation abdominal compression Active inspiration abdominal relaxation

4. Copyright © 2006 by Elsevier, Inc. Mechanics of Respiration Expiration Active Internal intercostals Internal Intercostals ribs Spine

5. Copyright © 2006 by Elsevier, Inc. Patm Palveolar Rest Inhalation due to expansion of chest cavity (Boyles law) Mechanics of Inhalation

6. Copyright © 2006 by Elsevier, Inc. Movement of Air In and Out of Lungs Pleural Pressures –Resting -5 cm H 2 0 –Inspiration -8 cm H 2 0 Alveolar Pressure –Resting 0 cm H 2 0 –Inspiration-1 cm H 2 0 –Expiration 1 cm H 2 0

7. Copyright © 2006 by Elsevier, Inc..50.25 0 +2 0 -2 -4 -6 -8 P r e s s u r e ( c m / H 2 O ) V o l u m e C h a n g e ( l i t e r ) Alveolar pressure Pleural pressure Transpulmonary Pressure Pressure and Volume Changes During Breathing Inspiration Expiration

8. Copyright © 2006 by Elsevier, Inc. Pulmonary Volumes Figure 37-6; Guyton & Hall

9. Anatomic Dead Space Low Blood Flow Physiologic Dead Space Definitions of Dead Space Copyright © 2006 by Elsevier, Inc.

10. Compliance of Lungs Determined by elastic forces Elastic forces –lung tissue –surface tension Lung Volume Change in Pleural Pressure Inhalation Exhalation -4 -8

11. Copyright © 2006 by Elsevier, Inc. Control of Bronchiolar Diameter Nervous –Sympathetics  2 receptors dilate –Parasympathetics Acetylcholine constrict Humoral –Histamine, acetylcholine » Constrict –Adrenergic (  agonists) » Relax

12. Copyright © 2006 by Elsevier, Inc. Airway Resistance during Forced Exhalation Guyton & Hall