01:146:356 Lecture Notes - Lecture 8: Intermolecular Force, Smooth Muscle Tissue, Lung Volumes
23 Mar 2016
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2nd photo- during expansion of the lungs/thorax, those net forces are directed outwardly. Chest wall is actually trying to expand these 2 opposing forces (external intercostals muscles vs internal intercostals muscles) set the stage for- sub-atmospheric interpleural pressure. Happens during inspiration third photo - show how the net forces balance to show sub atmospheric interpleural pressure, which is negative pressure and below barometric pressure. Boyle"s law: relates pressure and volume - pressure x volume is a constant, as one variable increases the other one must decrease. During inspiration the volume of the thorax and the volume of lungs both increase. So that means interpleural pressure must be decreasing and becoming more negative. That increases the anterior and posterior dimension of the thorax. really difficult to listen: ribs arranged obliquely. As diaphragm contracts it descendsincreases the superior dimension of the lungs. Because ribs are attached to the sternum higher than in the posterior,
