Chap 13 ppts - 1 Respiratory tract anatomy fig 13-1 2...

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Unformatted text preview: 1 Respiratory tract anatomy fig 13-1 2 Conducting zone vs. respiratory zone fig 13-2 3 Conducting zone functions Regulation of air flow trachea & bronchi held open by cartilaginous rings smooth muscle in walls of bronchioles & alveolar ducts sympathetic NS & epinephrine relaxation ( receptors) air flow leukotrienes (inflammation & allergens leukotrienes mucus & constriction) Protection mucus escalator (goblet cells in bronchioles & ciliated epithelium) inhibited by cigarette smoke Warming & humidifying inspired air expired air is 37 & 100% humidity (loss of ~400 ml pure water/day) Phonation larynx & vocal cords 4 Alveolar structure 1 fig 13-3b 5 Alveolar structure 2 fig 13-4a 6 Alveolar structure 3 fig 13-4b 7 Alveolar structure (notes) Type I epithelial cells thin, flat; gas exchange Type II epithelial cells secrete pulmonary surfactant pulmonary compliance (later) Pulmonary capillaries completely surround each alveolus; sheet of blood Interstitial space diffusion distance for O 2 & CO 2 is less than diameter of red blood cell Elastic fibers secreted by fibroblasts into pulmonary interstitial space tend to collapse lung 8 Lung pressures Lungs are inflated by being pulled open Transmural/transpulmonary pressure = P alveolar P pleural = 0 (-5) = 5 mm Hg 9 Lung pressures during quiet ventilation 10 Lung pressures during ventilation Purple line: alveolar pressure (P alv )-1 mm Hg during inspiration +1 mm Hg during expiration Green line: pleural pressure (P ip )-4 mm Hg at functional residual capacity-7 mm Hg after inspiration P tp is transpulmonary (transmural) pressure i.e. P alv P ip (e.g. at 2, -1 (-5) = 4 mm Hg Lower curve (black): labeling accidentally omitted x axis should read 4 sec i.e. time y axis is tidal volume = 500 ml 11 Pleural pressure during ventilation Quiet ventilation: pleural pressure (P ip ) always negative as lung expands, Pip becomes more negative because recoil (collapsing) force increases as lung stretches Forced ventilation: P ip negative during inspiration; more negative as lung expands P ip can be positive during forced expiration (e.g. FEV 1 measurement) 12 Airway resistance Transpulmonary pressure as lungs expand, pleural pressure becomes more negative transpulmonary pressure (alveolar pressure pleural pressure) increases alveoli expand, bronchioles expand airway resistance result: inhalation lowers resistance, exhalation increases resistance Lateral traction...
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Chap 13 ppts - 1 Respiratory tract anatomy fig 13-1 2...

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