BIO 468 Lecture Notes - Lecture 11: Intrapleural Pressure, Abdominal Cavity, Intercostal Muscle
9 Apr 2018
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Document Summary
Ventilation in air: oxygen availability is high, density of medium is low, dry. Ventilation strategies: evaporation across respiratory surface, therefore internally located. Mammals: respiratory system is located within the chest cavity, or thorax, upper respiratory tract, mouth, nasal cavity, pharynx, larynx, and trachea, lower respiratory tract, bronchi and alveoli (gas exchange surfaces) Increases compliance: decreases work of inspiration, promotes stability of alveoli, helps to keep the lungs dry, allows for re-inflation of the alveoli after a deep dive (lung collapses, this is very important for marine mammals. Lung structure: lungs are surrounded by the pleural sac, the pleural sac is two layers of cells with a small layer of fluid between them, the fluid-filled space is called the pleural cavity. It lubricates and allows two layers to slide past one another during ventilation. Intrapleural pressure is sub-atmospheric: chest wall pulls pleura out, lungs pull it in, opposing forces keep lungs inflated. It creates separation between thoracic and abdominal cavities.
