Chapter 41 Respiration

Chapter 41 Respiration - Chapter 41 Respiration I. The...

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Chapter 41 Respiration I. The Nature of Respiratory Systems A. Factors That Affect Gas Exchange 1 Fick’s Law a. Respiratory systems rely on the diffusion of gases down pressure gradients. 1) Partial pressures for each gas in the atmosphere can be calculated; for example, oxygen’s is 160mm Hg. 2) Gases will diffuse down a pressure gradient across a membrane if it is permeable and moist. b. According to Fick’s Law, the amount of diffusion depends on the surface area of the membrane and the differences in partial pressure. 2 Surface-to-Volume Ratio a. As an animal grows, its surface area increases at a lesser rate than its volume, making diffusion of gases into the interior a problem. b. Therefore, animals either must have a body design that keeps internal cells close to the surface (flatworms) or must have a system to move the gases inward. 3 Ventilation a. Animals have adaptations to move the air, or water, over the respiratory surfaces. b. Bony fish move the covers over the gills; sponges move the flagella on their collar cells; humans move the muscles of the thorax to expand and contract the chest cavity and move air in and out of the lungs. 4 Transport Pigments a. Hemoglobin is the main transport pigment. b. It binds four molecules of oxygen in the lungs (high concentration) and releases them in the tissues where oxygen is low. 5 Aquatic Environments a. Water holds much less oxygen than does air and is more dense and viscous. b. Water of high salt content and high temperature holds less oxygen; lack of sunlight and stagnation also reduce oxygen content. 6 Land Environments a. Air has more oxygen, but membranes are subject to drying. b. Air-breathing animals can have their oxygen reduced by excess water in their environments.
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This note was uploaded on 01/04/2012 for the course BSC BSC1005 taught by Professor Orlando,rebecca during the Fall '10 term at Broward College.

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Chapter 41 Respiration - Chapter 41 Respiration I. The...

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