BIO 152 Lecture Notes - Lecture 18: Air Sacs, Exhalation, Trachea
Document Summary
Unit 3: respiratory gas exchange mar 21 topic 18 (435748 ) All animals require oxygen for cell metabolism to minimize water loss, terrestrial animals have respiratory surface inside of the body. Mammal use lungs for gas exchange, trachea connects the lungs with the outside air. Gas exchange surfaces to keep up with o2 demands of the cell, gas exchange surface must have: thing diffusion distance and high surface areas. External gills - easier to ventilate but more vulnerable to damage. Internal gills - more protected, cost more energy. Gill arches - provide structural support for each wing of exchange surfaces. Each arch has two rows of flattened surfaces or filaments. Each filament contains many lamellae, the site of gas exchange. Exchange of gases across lamellae uses a counter- current mechanism. Fish gills use countercurrent exchange to maximize diffusion of gases across the blood/water surfaces.
