Bio100Ch44Notes - The Respiratory and Circulatory Systems...

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The Respiratory and Circulatory Systems Gas exchange involves 4 steps Ventilation occurs when air or water moves through a specialized gas exchange organs, such as lungs or gills Gas exchange takes place as O 2 and CO 2 diffuse between air or water and the blood at the ventilator surface Through circulation, the dissolved O 2 and CO 2 are transported throughout the body – along with nutrients, wastes, and other types of molecules – via the circulatory system In tissues, where cellular respiration has led to low O 2 levels and high CO 2 levels, O 2 and CO 2 diffuse between the blood and cells Respiratory system – collection of cells, tissues, and organs responsible for gas exchange between the individual and its environment. Circulatory system – responsible for moving O 2 , CO 2 and other materials around the body. (Some animals don’t have circulatory systems) Closed Circulatory system – system of vessels is continuous Transport tissues is blood Open Circulatory system – at least some vessels open into portions of the body cavity Transport system is hemolymph Animals with closed circulatory usually have two subsystems : A system of blood vessels that carries blood A system of lymph vessels filled with lymph – fluid that flows into lymph vessels from the spaces surrounding cells; it also contains specialized disease-fighting cells. The two circulatory subsystems are connected because lymph vessels eventually empty into blood vessels Blood and lymph are not separated in open circulatory systems Air and Water as Respiratory Media A) How do Oxygen and Carbon Dioxide Behave in Air? The atmosphere is made up of mostly Nitrogen, oxygen with trace amounts of argon and CO 2 It is important to express gas presence in terms of partial pressures instead of percentages. Pressure is a type of force Partial pressure – pressure of a particular gas in a mixture of gases, (you multiply the fraction of total composition of that gas by the total pressure exerted by the entire mixture)
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Oxygen and carbon dioxide diffuse between the environment and cells along their respective partial-pressure gradients, just as solutes diffuse along their concentration gradients (high partial pressure low partial pressure) B) How do Oxygen and Carbon Dioxide Behave in Water? To obtain oxygen in water is harder, because water is dense The amount of gas that dissolves depends on several factors Solubility of gas in water Temperature of the water Presence of other solutes Partial pressure of the gas in contact with the water Organs of Gas exchange Respiratory organs provide a greater surface area for gas exchange – enough to meet the demands of a large body filled with cells B) Design Parameters: The Law of Diffusion Fick’s law of diffusion – rate of diffusion of a gas depends on five parameters: the solubility of the gas in the aqueous film lining the gas-exchange surface, temperature, surface area
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This note was uploaded on 04/12/2010 for the course BIOLOGY 3363 taught by Professor Sokolove during the Fall '09 term at UMBC.

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Bio100Ch44Notes - The Respiratory and Circulatory Systems...

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