PHSL 310 Lecture Notes - Lecture 3: Alveolar Cells, Functional Residual Capacity, Obstructive Lung Disease
Document Summary
Airway resistance: resistance determined by length, tube radius, interactions between tubes, radius most important, inversely proportional to fourth power of radii, resistance is small, so small pressure for large flow, transpulmonary pressure: exerts force on airways. Bc tp increases during inspiration, radius larger, resistance lower. P= 2t/r: lateral traction: elastic ct fibers are pulled airways open even more between breaths, allows for lung to expand, physical factors airways get narrow and airway resistance increases, ep relaxes smooth by beta-a, whereas leukotrienes contract the muscle. Increased smooth muscle constriction causes airway obstruction, increases resistance. Chronic inflammation of airways makes smooth muscles hyperesponsive, they contract. Anti- inflammatory drugs (leukotriene and glucorticoids) used reduce ^. Chronic obstructive pulmonary disease: copd: emphysema, chronic bronchitis or both, causes difficulties in ventilation and oxygenated blood, chronic bronchitis: excessive mucus protection in bronchi and inflammatory changes in small airways, emphysema: cause is the collapse of small airways.
