Copyright © 2006 by Elsevier, Inc. Mechanics of Respiration Inspiration Resting –Diaphragm Active –Diaphragm –External intercostal muscles Diaphragm
Copyright © 2006 by Elsevier, Inc. Mechanics of Respiration Inspiration Active –Diaphragm –external intercostals Spine External Intercostals ribs
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
Copyright © 2006 by Elsevier, Inc. Mechanics of Respiration Expiration Active Internal intercostals Internal Intercostals ribs Spine
Copyright © 2006 by Elsevier, Inc. Patm Palveolar Rest Inhalation due to expansion of chest cavity (Boyles law) Mechanics of Inhalation
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
Copyright © 2006 by Elsevier, Inc 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
Copyright © 2006 by Elsevier, Inc. Pulmonary Volumes Figure 37-6; Guyton & Hall
Anatomic Dead Space Low Blood Flow Physiologic Dead Space Definitions of Dead Space Copyright © 2006 by Elsevier, Inc.
Compliance of Lungs Determined by elastic forces Elastic forces –lung tissue –surface tension Lung Volume Change in Pleural Pressure Inhalation Exhalation -4 -8
Copyright © 2006 by Elsevier, Inc. Control of Bronchiolar Diameter Nervous –Sympathetics 2 receptors dilate –Parasympathetics Acetylcholine constrict Humoral –Histamine, acetylcholine » Constrict –Adrenergic ( agonists) » Relax
Copyright © 2006 by Elsevier, Inc. Airway Resistance during Forced Exhalation Guyton & Hall