Esdin LS 2 Lec 9 Respiratory

Alveolar cell wall pulmonary surfactant interstitial

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Unformatted text preview: wall Pulmonary surfactant Interstitial fluid Macrophage CO2 Capillaries O2 Alveolus prevents infection, engulfs unwanted material Capillaries 0.5 µm Erythrocyte 4 4/21/13 Anatomy of an Alveolus •  Alveolar type I cells –  form the wall of the alveoli •  Alveolar type II cells surfactant, prevents –  Secrete _________ lungs from collapsing •  Macrophages –  Ward against foreign bodies protection Lungs Chest wall Pleural sac when inhaling chest cavity increases in size, lungs expand when exhaling, the opposite occurs Lung 5 4/21/13 Pressure Change •  Atmospheric Pressure (Patm) •  Alveolar pressure (Palv) •  Intrapleural pressure (Pip) Boyle s Law 1/2 volume Double the pressure pressure inside lungs lower than 1 atm Volume Pressure Double the volume 1/2 pressure 6 4/21/13 Lungs Chest wall Pleural sac Lung 760 mmHg Lung 754 mmHg Pleural sac 760 mmHg Chest wall Pressure and Volume Change inspiration expiration Patm Patm Palv Palv this causes breathing to take very little energy 7 4/21/13 Pressure and Volume Change •  During inspiration the volume of the lungs increases and the pressure decreases •  During expiration, the volume of the lungs decreases and the pressure increases Inspiration External intercostal muscles Diaphragm Rest Inspiration 8 4/21/13 Expiration when you expel air out internal intercostal muscles Abdominal muscles squeeze organs making it smaller, forcing air out Passive expiration Active expiration atelectasis: no surfactant, collapsed alveoli (collapsed lung) Muscles of Expiration •  Passi...
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