PHGY 210 Lecture Notes - Lecture 7: Alveolar Pressure, Airway Resistance, Intercostal Muscle
6 Apr 2017
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Document Summary
The respiratory system may be regarded as a pump with elastic and flow-resistive properties. At rest, the lungs are at frc and ppl is negative due to the opposite forces acting on the lungs and chest wall. During inspiration, the diaphragm contracts and the chest wall is pulled open. During inspiration, muscle contract pull on the chest and this decreases the pleural pressure => pull the alveoli open (alveoli move to the larger circle. ) Alveolar space is now bigger, and the pressure inside goes down due to decompress the air. During expiration, the brain tell the muscle to stop contracting, they relax and the rib cage moves inward. The pleural pressure become less negative, they recoil. (think: stop pulling the balloon) and this will increase the pressure in alveolar space. The air flow from in side to out side. The equation here is the same as we talk about blood flow, f (flow)
