cardiovascular system-1

cardiovascular system-1 - Gas Exchange in Animals Gas...

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Gas Exchange in Animals
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Gas Exchange in Animals Physical Processes of Respiratory Gas Exchange Adaptations for Respiratory Gas Exchange Gas Exchange in Human Lungs Blood Transport of Respiratory Gases Regulation of Breathing
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Physical Processes of Respiratory Gas Exchange The respiratory gases are oxygen (O 2 ) and carbon dioxide (CO 2 ). • Cells require O 2 from the environment to produce ATP by cellular respiration. Cellular respiration produces CO 2 as an end product, which must be lost to the environment to prevent toxic effects. Diffusion is the only means to exchange these gases.
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Physical Processes of Respiratory Gas Exchange It is easier to obtain O 2 from air than from water. • The O 2 content in air is about 20 times higher than in water. O 2 diffuses 8,000 times more rapidly in air. Breathing air, which is less dense and less viscous than water, requires less work for the animal.
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Physical Processes of Respiratory Gas Exchange Slow molecular diffusion of O 2 is a problem because O 2 must diffuse through the aqueous cytoplasm of the cell to reach the mitochondria. Diffusion of O 2 in water is so slow that even cells with low metabolism must be only 1–2 mm from the O 2 source. Animals that have no internal transport of O 2 are either severely limited in size or
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Adaptations for Respiratory Gas Exchange In mammal lungs, ventilation is tidal : Air flows in and out by the same route. At rest, the amount of air exchanged is the tidal volume . The additional volume of air taken in by inhaling deeply is the inspiratory reserve volume . The additional volume we can exhale is the expiratory reserve volume . The total of these three volumes in the
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Figure 48.9 Measuring Lung Ventilation
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Adaptations for Respiratory Gas Exchange Even with forceful breathing, there is residual volume of air that keeps the lungs from collapsing. Some of this exists in what is called the anatomical dead space— airways in which gas exchange cannot occur. The total lung capacity is the sum of the residual volume and the vital capacity.
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Adaptations for Respiratory Gas Exchange In tidal breathing, the incoming air mixes with the stale air remaining in the lung, which severely limits the P O2 gradient. The volume of this stale air is the sum of the residual volume and the expiratory reserve volume. Tidal breathing also reduces gas exchange efficiency by not permitting countercurrent gas exchange between air and blood. To offset the inefficiencies of tidal
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Gas Exchange in Human Lungs The air pathway in humans consists of the following components: An oral or nasal cavity, followed by the pharynx (an area for both food and air). The
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This note was uploaded on 04/02/2008 for the course BIO 188 taught by Professor Capco during the Fall '08 term at ASU.

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cardiovascular system-1 - Gas Exchange in Animals Gas...

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