BPK 205 Lecture 26: BPK 205 Notes Lecture 26

• School: Simon Fraser University
• Department: Biomedical Physio & Kines
• Course: BPK 205
• Professor: Nadine Wicks

Document Summary

Objectives: describe the function of surfactant on alveolar surface tension. Functions: decrease surface tension inside alveoli, preventing collapsing, make expanding easier. Decrease surface tension at air-fluid meeting point, air pulls fluid surface inward [law of. Patm = 760 mmhg (0 mmhg used as reference); intrapleural p (pip) = 756 mmhg (-4 mmhg relative); intra-alveolar p (palv) = 760 mmhg (0 mmhg relative); palv pip = 4 mmhg (transpulmonary p (ptp)) Pip = -4 mmhg = subatmospheric pressure (lower pressure than patm) required to maintain elastic recoil of lungs and chest wall keep lungs inflated. Pneumothorax = collapsed lung: punctured lung air enters pleural sac pip no longer negative lung no longer inflated by difference in pressure collapsed lung. Chest expansion decrease pip increase ptp (palv pip) increase force pulling lungs toward chest wall lungs/alveoli expand decrease palv air flow into alveoli following pressure gradient until palv = patm.