PHGY 312 Lecture Notes - Lecture 5: Vascular Resistance, Pulmonary Artery, Alveolar Pressure
24 May 2016
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Document Summary
Capillaries in the lung is surrounded by air; different from other vessels in the. St determines recoil of the lung; creates negative pressure interstitial space; air is sucked in pressure o o o o o o. Peak pressure of pulmonary artery is much lower than the distending. Effect of lung volume on pulmonary vascular resistance: Pvr increases in alveolar vessels at high lung volumes. Pvr decreases in extra-alveolar vessels at high lung volumes. Effect of vascular pressure on pulmonary vascular resistance: As we increase venous pressure, resistance goes down. If you increases arterial pressure, resistance also goes down (r vs q graph) Increasing arterial pressure has a greater negative exponential slope. Low o2 air vessel gets constricted so that ventilation/perfusion ratio increase in that region. Vestigial form of what we had during fetal life (low o2) Helped close pulmonary artery; fetus" lungs not for gas exchange (shunt)
