In a human, the aorta directlyattaches toA. the top of the right atrium.B. the top of the right ventricle.C. the bottom of the left ventricle.D. the top of the left ventricle.E. the bottom of the right atrium.LE 42-8Pacemakergenerates wave ofsignals to contract.Signals are delayedat AV node.Signals passto heart apex.Signals spreadthroughoutventricles.SA node(pacemaker)ECGAV nodeBundlebranchesHeartapexPurkinjefibersLE 42-9EndotheliumEndotheliumSmoothmuscleConnectivetissueCapillary100 µmBasementmembraneEndotheliumSmoothmuscleConnectivetissueValveArteryArterioleVenuleVeinArteryVeinLE 42-10Valve (open)Skeletal muscleValve (closed)Direction of blood flowin vein (toward heart)LE 42-11SystolicpressureVenae cavaeVeinsVenulesCapillariesArteriolesArteriesAortaDiastolicpressurePressure (mm Hg)120100806040200Area (cm2)5,0004,0003,0002,0001,0000Velocity (cm/sec)50403020100LE 42-13abPrecapillary sphinctersThoroughfarechannelCapillariesVenuleArterioleSphincters relaxedVenuleArterioleSphincters contractedLE 42-14CapillaryRed bloodcell15 µmTissue cellCapillaryNet fluidmovement outINTERSTITIAL FLUIDNet fluidmovement inBlood pressureOsmotic pressureInward flowDirection ofblood flowPressureOutward flowVenous endArterial end of capillaryFluid Return by the LymphaticSystem• The lymphatic system returns fluid tothe body from the capillary beds• This system aids in body defense• Fluid reenters the circulation directly atthe venous end of the capillary bed andindirectly through the lymphatic systemLE 42-15SodiumPotassiumCalciumMagnesiumChlorideBicarbonateOsmotic balance,pH buffering, andregulation ofmembranepermeabilityPlasma 55%ConstituentMajor functionsWaterSolvent forcarrying othersubstancesIons (blood electrolytes)AlbuminOsmotic balance,pH bufferingPlasma proteinsFibrinogenImmunoglobulins(antibodies)ClottingDefenseNutrients (such as glucose, fatty acids, vitamins)Waste products of metabolismRespiratory gases (O2 and CO2)HormonesSubstances transported by bloodCellular elements 45%Cell type NumberFunctionsper µL (mm3) of blood5–6 millionTransport oxygenand help transportcarbon dioxideLeukocytes(white blood cells)5,000–10,000Defense andimmunityMonocyteBasophilEosinophilLymphocyteNeutrophilPlateletsBlood clotting250,000–400,000Erythrocytes(red blood cells)SeparatedbloodelementsLE 42-17Endothelium ofvessel is damaged,exposing connectivetissue; platelets adherePlatelets form a plug Seal is reinforced by a clot of fibrinCollagen fibersPlatelet plugPlatelet releases chemicalsthat make nearby platelets stickyClotting factors from:PlateletsDamaged cellsPlasma (factors include calcium, vitamin K)Prothrombin ThrombinFibrinogen FibrinFibrin clot Red blood cell5 µmConcept 42.5: Gas exchangeoccurs across specializedrespiratory surfaces• Gas exchange supplies oxygen for cellularrespiration and disposes of carbon dioxide• Animals require large, moist respiratorysurfaces for adequate diffusion of gasesbetween their cells and the respiratorymedium, either air or waterLE 42-19Respiratorymedium(air or water)OrganismallevelCellular levelEnergy-richfuel moleculesfrom foodRespiratorysurfaceCirculatory systemCellular respirationCO2O2ATPLE 42-20cGillsScallopLE 42-20dGillsCrayfishLE 42-21GillarchWaterflowOperculumGillarchBloodvesselOxygen-richbloodWater flowover lamellaeshowing % O2GillfilamentsO2Oxygen-poorbloodLamella15%40%70%100%90%60%30%5%Blood flowthrough capillariesin lamellaeshowing % O2Countercurrent
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