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Lesson 14: Animal Blood CirculationWhy circulatory system?Responsible for the delivery of oxygen and nutrients to all cells as well as removing carbon dioxide in waste productsSingle celled organismsoUse their cell surface for point of exchange with external environmentMulti-cell organismsoMust transport throughout the bodyoMust have circulatory systemoThree purposes for thisTransportationRegulationBy carrying regulatory hormones and tempProtection Mechanical wounds and invading pathogensComposition of Blood- formed elementsPlasmaoMade most of wateroFormed elements:ErythrocytesoHemoglobinBinds and transports oxygen25% of total volume of bloodLeukocytesoWhite blood cellsoLess than 1 percent of bloodPlateletsoCell fragments used in blood clottingStem cells and the production of formed elements:Begins in bone marrowPluripotent stem cellsHematopoiesisoWhen oxygen availability drops the kidney converts plasma protein:Erythropoietin (EPO)oStimulates production of erythrocytes oIncreases O2 capacityErythropoiesisoAction is called
Platelets and Blood ClottingSlowlyTypes of Circulatory Systems
No circulatory system:Sponges-Circulate water through incurrent and deterrent poresNematode-Digestive tractOpen/Closed Circulatory-No distinction between extracellular and circulatory fluid this is called hemolymphLeaks out cellOnce it’s out of circulatory system is called lymphNo capillarieshemolymphCapillariesBlood + lymph
Fish Heart and CirculationTwo pumping chambersLow blood pressure past gills (no separate pulmonary circuit)Closed circulatoryOnce it leaves the heart first goes to gills where it unloads carbon dioxide to external