BMS 420 Lecture Notes - Vasoconstriction, Alveolar Cells, Bronchiole
Document Summary
V and p are essential elements in normal lung function but v:p ratio of ~. 8 is not necessarily a dictation of normal v and p! Pco2 in alveoli = pco2 in arterial blood. Po2 in alveoli > po2 in arterial blood. Regional differences in ventilation perfusion disappear with exercise. The alveolar gas assumes the composition of inspired air. Po2, pco2, and ph around smooth muscle causes bronchiolar constriction, diverting airflow to normal airways. In response to blood flow, alveolar type ii pneumocytes produce less surfactant, causing compliance and ventilation (alveoli shrink) Because ventilation to lung stops, while perfusion continues, The alveolar gas assumes the composition of mixed-venous blood. In response to local alveolar hypoxia, the arterioles feeding the alveoli constrict: hypoxic vasoconstriction. Local control of arterioles and bronchioles by oxygen and carbon dioxide. Pco2 increases bronchioles dilate, pulmonary arterioles weakly constrict, systemic arterioles dilate. Pco2 decreases bronchioles constrict, pulmonary arterioles weakly dilate, systemic arterioles constrict.
