10 1 Introduction to Respiration 10 1 Intro to Respiratory Systems lecture pdf https utexas instructure com courses 1099761 files 35193672 download verifier pM8mkQr4FztA55jtLPgNQzOWcDMiwkT8mB0jvbvi wrap 1 https utexas instructure com courses 1099761 files 35193672 download verifier pM8mkQr4FztA55jtLPgNQzOWcDMiwkT8mB0jvbvi wrap 1 Slide 13 The efficiency of hemoglobin and gas transport can be regulated using different globin genes The sequence of the globin genes and its regulatory regions differ between species reflecting adaptive evolution of hemoglobin Hb to particular habitats and behaviors For example diving mammals have unusually high Hb allowing them to maintain activity without inspiring Many Antarctic icefish have lost their Hb genes altogether These fish have very low metabolic rates and low environmental temperatures increase O2 solubility in the surrounding water and in their blood Their extreme habitat allows them to survive without hemoglobin Perhaps as compensation they have large hearts blood vessels and blood volume compared to non Antarctic relatives Affinity of Hb for O2 also varies between different globins which is expressed as P50 PO2 for 50 saturation analogous to Km for enzymes Just like with Km an Hb protein with a lower P50 will be more efficient as it will be 50 saturated at a lower partial pressure of O2 due to its higher affinity for O2 Many animals have multiple Hb genes that are expressed in a tissue specific manner each of which has a different P50 For example the worm Pista pacifica image on slide is another Terebellidae polychaete worm but they look similar has three different globin genes that are expressed in different parts of its body The worm has low affinity Hb in its blood medium affinity Hb in its coelom interstitial fluid and high affinity myoglobin in its body wall This worm lives in burrows up to a meter down into anoxic no O2 mudflats At high tide the worms emerge and extend their gills into the highly oxygenated water flowing in above their mudflat The plentiful O2 diffuses into the gill capillaries where it binds low affinity Hb When the blood flows to the body cavity the bound O2 is passed to the medium affinity Hb in its body cavity which passes it to the high affinity globin proteins in the active muscle cells By creating an affinity gradient Pista is able to transport increasing amounts of O2 to tissues with increasing metabolic demands Slide 14 Many animals have mechanisms for bulk flow water air throughout body or circulation of specialized fluid in circulatory system to supplement diffusion The direction of bulk flow of fluids both liquid and gas is determined by gradients of pressure Circulatory and respiratory systems are able to direct the flow of fluid by changing the volume of the container heart blood vessels lungs etc which changes pressure This is formalized in Boyle s Law P1V1 P2V2 where 1 is starting pressure and volume and 2 is final pressure and volume Given a particular starting pressure and volume if you then make the container smaller decrease V2 pressure P2 inside it will increase If you open the container the fluid will flow outward into a lower pressure area until the pressure inside and outside the container are equal This is the basis of how the lungs of terrestrial animals work which will be in your homework on Friday Expand the container which decreases pressure on the air inside in lungs Open a channel to the outside where pressure is relatively higher The fluid air flows down the total pressure gradient into the lungs but only until pressure inside and outside are equal Friction will resist this flow Q P R so smaller tubes will be more resistant to flow Respiratory systems must work within these physical constraints pressure gradients and factors that affect flow such as resistance
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