CAS BI 315 Lecture Notes - Lecture 1: Escalator, Bronchus, Skeletal Muscle
9 Jan 2017
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Document Summary
Respiratory system: any structure in an animal that promotes the exchange of o2/co2 with the environment, respiratory surface: surface across which the gases are actually moved o very high surface area, very vascular o alveoli. Epithelial cells on the surface have cilia, which beat in unison in one direction (upwards) o air moves down, mucus moves up. Mucus layer encompasses the cilia and is relatively thick and viscous. As cilia beat up, they bring mucus with it (mucus escalator) Also brings pollutants that were ingested back up with mucus. Mucus moves back up to the pharynx, where it is swallowed: keeps lungs clear of particulate matter and bacteria/dust. Cystic fibrosis mucous layer becomes thick and dehydrated, obstructing airways o bifurcates and becomes 2 bronchi. Leads to thousands of bronchioles, which collect into alveoli on respiratory surface o figure 13. 3: bronchioles.
