100CRespiratorySystem

100CRespiratorySystem - Respiratory System The collection...

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Unformatted text preview: Respiratory System The collection of cells, tissues, and organs responsible for gas exchange between the individual and its environment. Respiration (gas exchange)the uptake of O 2 from the environment, and release of CO 2 to the environment Gas exchange involves four steps 1) Ventilation any method of increasing contact between the respiratory medium (oxygen source e.g. water or air) and the respiratory surface (e.g. gills, skin, lungs) 2) Gas exchange diffusion of O 2 and CO 2 between respiratory medium and respiratory surface 3) Gas transport (circulation) of O 2 and CO 2 throughout the body by the circulatory system 4) Gas exchange of O 2 and CO 2 between blood and tissue cells (in response to use of O2 and release of CO2 by cellular respiration ) Relationship between respiratory and circulatory systems via the four steps in gas exchange Mitochondria 1 . Ventilation Ventilatory surface Environment 3 . Circulation 2 . Gas exchange 4 . Cellular respiration Circulatory system Blood Respiratory system Oxygen source (respiratory medium) for terrestrial organisms is the air, which is 21% O 2 Oxygen source (respiratory medium) for aquatic organisms is O 2 dissolved in water, which is in lesser and variable amounts Gas movement between respiratory surface (skin, gills, lungs) and environment is by diffusion The respiratory surface is thin with a large surface area , and must be moist because O 2 and CO 2 diffuse dissolved in water The respiratory surface is separated by a thin epithelium from blood or capillaries Respiratory surfaces are extensively folded or branched for increased surface area e.g. gills, tracheae, lungs Basic Features of Respiratory Systems Gills Gill Respiration Gills outfoldings of body surface suspended in water Ventilation creating current across gillsin fish a current of water enters mouth, crosses slits in the pharynx, passes over the gills, and exits the body Capillary arrangement in the gills enhances gas exchange Salmon gills Fish Gills Are a Countercurrent Exchange System Gill arches hold many gill filaments Detail of gill filament: Water flow Blood flow Capillaries Gill lamella To body From heart Water IN Water OUT Figure 44-8 Countercurrent flow (seen in fish gills) Water flow over lamellae (% oxygen) Diffusion stops Co-current flow (not seen in fish gills) Blood flow through lamellae (% oxygen) Water flow over lamellae (% oxygen) Blood flow through lamellae (% oxygen) 100% 70% 100% 40% 15% 90% 70% 90% 60% 10% 30% 30% 5% 0% 50% 50% O 2 O 2 Countercurrent exchange 1) Blood flows in opposite direction to the movement of water across gills 2) Water always has a higher O...
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100CRespiratorySystem - Respiratory System The collection...

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