Problem Set I Key 2010

# Problem Set I Key 2010 - Problem Set I: Respiratory Gas...

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Problem Set I: Respiratory Gas Exchange 1) The following data have been reported for a water-breathing aquatic salamander, Siren intermedia . Body mass: 13.7 grams Rate of oxygen consumption: 452 μL O 2 per hour Total surface area of skin: 57.53 cm 2 Partial pressure of oxygen in water: 110 mm Hg Partial pressure of oxygen in blood vessels of skin: 25 mm Hg Skin thickness (assumed diffusion distance to blood capillaries): 100 μm Temperature: 20 ° C a. What is the gradient of P O2 across the skin of the salamander? SOLUTION: Be definition, the ‘gradient’ of P O2 is the change of P O2 per unit distance. Thus, gradient of P O2 = (110 25 mm Hg) / 100 μm = 0.85 mm Hg/ μm b. Estimate the amount of oxygen diffusing through the skin and express the diffusion rate relative to the oxygen partial pressure in the following units μL O 2 /(h cm 2 mm Hg) Assume the difference in oxygen between water and blood is a steady state condition. In essence, you are calculating the conductance (diffusing capacity) of skin for oxygen in area-specific units. SOLUTION: Oxygen diffusing = (452 μ L O 2 /h)/[(57.53 cm 2 )(110-25 mm Hg)] = (452 μ L O 2 /h)/[(57.53 cm 2 )(85 mm Hg)] = 0.0924 μ L O 2 /(h cm 2 mm Hg)

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2 c. Estimate Krogh’s diffusion constant for the skin of this animal and compare it to the values for various materials listed below. Note the data below are in units of cm 3 O
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## Problem Set I Key 2010 - Problem Set I: Respiratory Gas...

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