PHGY 210 Lecture 12: Lecture 12
4 Feb 2019
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Document Summary
Dynamics of a breath: today"s focus = airways and the dynamics of breathing, look at the picture to the right = it is an analogy of respiratory system. Picture: we attach a syringe to the tip of a balloon and we pull on the plunger, decreasing the pressure around the balloon and making it increase in size. Analogy: the same process happens when we breathe; we decrease the pleural pressure by pulling the chest open. As a result, the molecules of air inside the alveoli have more space to move around and so the gas is decompressed. Therefore, the alveolar pressure is less than atmospheric pressure so air flows from outside inside due to the pressure gradient. Expiration (palv > patm): brain tells muscle to stop contracting, muscles relax, chest recoils down, pleural pressure becomes less negative (since we"re not pulling the chest wall open anymore) and the lungs collapse.
