KINE 3012 Lecture Notes - Lecture 3: Transpulmonary Pressure, Intrapleural Pressure, Intercostal Muscle

• School: York University
• Department: Kinesiology & Health Science
• Course: KINE 3012
• Professor: Michael Connor

Document Summary

Expiration: diaphragm & intercostal muscles relaxes; intrapleural pressure increases, thoracic gets smaller, intrapleural space gets smaller & pip increases (from 754 back to 756mmhg, relaxing diaphragm results in drop in transpulmonary muscles (from. 6mmhg to 4mmhg); the recoil remains the same: alveoli collapses to equalise pressure. Expiration is a passive process: b/c transpulmonary pressure (holding lung open) > recoil (pulling lung closed) after expiration, the lung will be forced to close. As lung gets smaller due to balance b/t recoil & transpulmonary, alveoli gets smaller. When alveoli gets smaller, alveolar pressure increases above atmospheric pressure- this results in change in pressure & air gets pushed out. Increase in intrapleural decreases pressure of transpleural: before: ptp=6mmhg; recoil=6mmhg, after: ptp=4mmhg; recoil=6mmhg. Intrapleural pressure goes up, transpulmonary pressure goes down. Pressure trying to close lung than pressure trying to keep lungs open is greater causing lungs to compress. Alveolar pressure increases- above atmospheric pressure causing air to be pushed out.