Lecture11 - Lecture 13: Circulation and Gas Exchange...

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Lecture 13: Circulation and Gas Exchange Chapter 42
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organic energy (carbohydrate) ATP (usable cellular energy) mitochondria C 6 H 12 O 6 ATP
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organic energy (carbohydrate) ATP (usable cellular energy) C 6 H 12 O 6 + O 2 CO 2 + H 2 O + ATP oxygen carbon dioxide mitochondria O 2 CO 2
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J = D x A x (C1 - C2) / L Fick’s Law - equation describing factors that affect diffusion rates of molecules (such as oxygen) across a membrane J = diffusion rate across absorptive surface D = constant A = surface area of absorptive surface C1 = concentration of molecule on side A of surface C2 = concentration of molecule on side B of All gas exchange between environment and cells occurs via diffusion!
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J = D x A x (C1 - C2) / L J = diffusion rate across absorptive surface D = constant A = surface area of absorptive surface C1 = concentration of molecule on side A of surface C2 = concentration of molecule on side B of surface L = distance traveled of C1 molecule to C2 low oxygen HIGH oxygen J = D x A x (C1 - C2) / L J = 1 x 100 x (100 - 10) / 1 J = 9000 mol/m 2 /sec how about if we increase our surface area to 500?
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HIGH oxygen J = D x A x (C1 - C2) / L J = 1 x 500 x (100 - 10) / 1 J = 45,000 mol/m 2 /sec J = D x A x (C1 - C2) / L J = diffusion rate across absorptive surface D = constant A = surface area of absorptive surface C1 = concentration of molecule on side A of surface C2 = concentration of molecule on side B of surface L = distance traveled of C1 molecule to C2 large increases in A (or decreases in L) lead to much higher diffusion rates
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low oxygen HIGH oxygen Diffusion time of molecules through media is inversely proportional to the square of the distance traveled d = diffused distance D = constant t = time d 2 = 2Dt if d = 10, then t = 50 100 = 2 (1) 50
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low oxygen HIGH oxygen simple diffusion is sufficient for cells close to the surface, but as we increase our distance traveled the time to achieve diffusion increases greatly Diffusion time of molecules through media is inversely proportional to the square of the distance traveled d = diffused distance D = constant t = time d 2 = 2Dt if d = 100, then t = 5000 10,000 = 2 (1) 5000
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Diffusion time of molecules through media is inversely proportional to the square of the distance traveled d t 0.1mm 1s 1mm 100s 1cm 3 hours
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This note was uploaded on 11/24/2011 for the course BIOLOGY 110 taught by Professor Bentz during the Spring '09 term at Drexel.

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Lecture11 - Lecture 13: Circulation and Gas Exchange...

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