Biology 2601A/B Lecture Notes - Lecture 14: Countercurrent Exchange, Gas Exchange, Partial Pressure
13 Nov 2018
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Document Summary
Water requires moving 23,000 times more mass across the gills compared to air breathing lung. Water is more viscous, doesn"t like to flow as much as air: water provides more resistance to movement of oxygen molecules. Lungs are invaginated into the body and contain the environmental medium. External gills are evaginated from the body and project directly into the environmental medium. Internal gills are evaginated from body and project into a superficial body cavity. Mammals: breathe in 27%, tuna breathe in 45% Active: unidirectional: medium is flowing in on direction, tidal: movement in and out, nondirectional: wave their gills around in water. Outflow concentration is always lower than what"s in the lung (po2 is lower than environment) With tidal gas exchange, you have fresh air coming in and it"s going to mix with stale air/fluid that is already in the tidal system.
