1 10 1 10 2 Respiratory Systems BIO 361T Fall 2014 1 How does the mitochondria set up an O2 gradient Why is this relevant in all animals from unicellular to those with the largest most complex bodies During oxidative phosphorylation the mitochondria uses O2 so O2 decreases from the cell membrane to the mitochondria This gradient drives O2 diffusion toward the mitochondria which suffices for all diffusion in unicellular animals 2 Why is a circulatory system without a respiratory system sufficient to support life in earthworms Explain in terms of Fick s Law A is high relative to volume and L is low 3 Why do earthworms die if they are in the sun for too long In terrestrial animals O2 has to dissolve before it can diffuse into tissues Cutaneous respiration depends on moist skin If earthworms dry out they cannot breathe and their cells die 4 In terms of respiratory challenges why are there no frogs the size of elephants Thin skin makes animal too vulnerable to be that large 5 Larger animals have respiratory systems as well as circulatory systems How does a respiratory system overcome the physical limitations of diffusion in a large body Explain in terms of Fick s Law Increases A for given volume while keeping L low 6 Use Fick s Law to explain how unidirectional ventilation can be more efficient than tidal ventilation if it is combined with a countercurrent exchanger Maximizing the partial pressure gradient same conceptually as C1 C2 but remember to use partial pressure for gases Tidal ventilation mixes deoxygenated and oxygenated air at the respiratory surface so the maximum blood oxygen level will be below environmental oxygen levels With concurrent flow unidirectional ventilation causes O2 to diffuse from medium to blood until it reaches equilibrium so maximum blood oxygen level will be below environmental oxygen levels However with countercurrent flow blood constantly encounters more concentrated medium so maximum blood oxygenation will be comparable to environment levels 7 Use the ideal gas law PV nRT to explain why animals cannot rapidly go from deep water to shallow water Gases dissolved in the blood will expand creating bubbles in the bloodstream P is lower in shallower water If n R and T stay constant as an animal surfaces V must increase to compensate so the volume that that same amount of gas occupies will increase as environmental pressure on the animal s body decreases The bends in scuba diving 2 8 Use Henry s Law G Pgas x Sgas to explain why air has a higher concentration of O2 than water G is higher in air because S is higher At equilibrium partial pressure of O2 in air and water will be equal Only concentration differs 9 Use Henry s Law to explain why most active water breathers must ventilate their gills unidirectionally while tidal breathing is sufficient in comparably sized air breathers Because S is lower in water animals with similar metabolic rates have to be more efficient at getting O2 from water than air Unidirectional flow is more efficient than tidal breathing Not related to Henry s Law tidal breathing takes extra energy in water to reverse the direction of flow of the viscous medium 10 Given that CO2 is slightly heavier than O2 but 24x more soluble in water explain why CO2 diffuses much faster in water than O2 does Graham s Law which states that diffusion rate is proportional to solubility square root of molecular weight of substance 11 What would happen at the respiratory surface if the metalloprotein genes in an animal were knocked out Without metalloproteins gases would reach equilibrium quickly and the blood would be insufficiently oxygenated to support the animal s metabolic needs 12 Why do animals that use hemerythrins or hemoglobins require iron in their diet What happens when iron intake is low Iron is the metal in the middle of the metalloprotein bound to hemerythrin protein bound to the heme group in hemoglobin Insufficient binding of O2 and thus low levels of O2 in the blood to the tissues 13 Why is the Bohr effect advantageous in highly active tissues Active tissues produce more CO2 which causes more H production in the blood via carbonic anhydrase H binds Hb and reduces its affinity for O2 causing it to release O2 in active tissues where it is needed most 14 Why is the Haldane effect advantageous in highly active tissues When Hb does not carry O2 it can carry more H which causes more HCO3 production via carbonic anhydrase This allows the blood to carry more CO2 which is abundantly produced by active tissues
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