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26 Cards in this Set
- Front
- Back
Diffusion of C02 from cells into tissue capillaries occurs how?
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C02 diffuses down its partial pressure gradient--diffusion equilibrium normally occurs
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Intracellular PC02 is ____; interstitialy PC02 is ______; PC02 of arterial blood entering the tissues is _____.
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46, 45, 40
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Transport of C02 in the blood- 3 forms?
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1. Co2 dissolved in plasma water
2. Bicarbonate ion 3. Carbaminohemoglobin |
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At venous blood PC02 is ____, the amount of dissolved CO2 is about ________mL/100mL.
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45, 2.7
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Approximately what % of blood CO2 is transported as dissolved in plasma water?
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7%
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How is carbonic acid formed?
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Co2 in the blood reacts with water inside RBCs, the reaction is catalyzed by the enzyme carbonic anhydrase present in RBCs
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Carbonic acid ionizes to yield?
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hydrogen and bicarbonate ions
1) H+ is buffered by Hb 2. HCO3- diffuses out of the RBC in exchange for Cl- |
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What % of blood CO2 is transported in bicarbonate?
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70%
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Carbaminohemoglobin is formed how?
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C02 reacts reversible with the terminal amine group of the hemoglobin molecule
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Approximatey what % of blood C02 is transported in carbaminohemoglobin?
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23%
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Describe the diffusion of C02 from pulmonary capillary blood into the alveolar gas?
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Co2 diffuses down its partial pressure gradient, PC02 of blood entering the pulmonary capillary is 45 mmHg; alveolar PC02 is 40 mmHg, diffusion equilibrium normally occurs
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What does the carbon dioxide "dissocation" curve relate?
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total C02 in the blood to PC02
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CO2 unloading in the lung is facilitated by?
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oxygen loading
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Haldane effect
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When oxygen binds with hemoglobin, C02 is released to increase C02 transport
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What causes Hb to become a stronger acid?
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Binding of oxygen to Hb
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If oxygen is binding to Hb what is displaced?
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C02 bound as carbaminohemoglobin
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What else is displaced due to oxygen binding to Hb and creating a stronger acid?
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H+ bound to Hb are also displaced and combine with bicarbonate to form carbonic acid which yields Co2 and H20
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In the tissue capillaries, what is different about the Haldane effect?
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It works in the opposite direction - oxygen unloading shifts the C02 dissocation curve to the left or upward (relative to its position in the lungs) and facilitates C02 uptake
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The amount of Co2 that can be released from blood in the lungs, and taken up by blood in the tissues, is ______ by the Haldane effect.
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Doubled
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What is the respiratory exchange ratio, or respiratory quotient (R)?
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is the ratio of C02 production to 02 consumption
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Normally at rest, how much oxygen per 100 mL blood is transported from the lung to the tissues? and how much C02 is transported from the tissues to the lungs?
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5 mL , 4 mL
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So if 5 mL is transported from lung into the tissues, and 4 mL is transported from tissues to the lungs, how would you describe C02 excretion?
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normally about 80% of oxygen uptake and R is 0.8
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The actual value of R depends on?
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the metabolic substrates being utilized for cellular ATP production
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If a person were using only carbohydrate for metabolism, R would be?
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1.0
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If a person were using only FA for metabolism, R would be?
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0.70
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For a person consuming a normal diet consisting of carb, fat, and protein, R is approximately?
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0.80
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