PHGY 210 Chapter Notes - Chapter 13.1-13.2: Alveolar Cells, Transpulmonary Pressure, Intrapleural Pressure
18 Mar 2017
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13. 1 organization of respiratory system: alveoli: small air-containing sacs, 300 million of them, site of gas exchange with blood, at rest, around 4l of fresh air enters and leaves per minute (increase up to x20 during intense exercise) Alveoli: type i alveolar cells: flat, one-cell thick epithelial cells that line air-facing surface, type ii alveolar cells: thicker specialized cell producing surfactant (detergent-like, thin barrier and large surface area between air in alveoli and blood (gas diffusion) Lungs: pleural sac: surround each lungs, two layers (visceral --attached to lungs and parietal --attached to thorax & diaphragm) separated by intrapleural fluid, normal breathing results from changes in intrapleural pressure; hydrostatic pressure of intrapleural fluid. Patm and alveoli compresses: boyle"s law p1v1=p2v2 (as volume increases, pressure decreases) Pressure: transpulmonary pressure (ptp): pressure difference between inside & outside of lungs, how stretchable the lungs are also affect how much they expand.
