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LO 2.25 The student can construct explanations based on scientific evidence that homeostatic mechanisms reflect continuity due to common ancestry and/or divergence due to adaptation in different environments.LO 2.27 The student is able to connect differences in the environment with the evolution of homeostatic mechanisms.LO 4.8 The student is able to evaluate scientific questions concerning organisms that exhibit complex properties due to the interaction of their constituent parts.LO 4.9 The student is able to predict the effects of a change in a component(s) of a biological system on the functionality of an organism(s).LO 4.10 The student is able to refine representations and models to illustrate biocomplexity due to interactions of the constituent parts.Ch. 42 Circulation and Gas Exchange42.1 Circulatory Systems Link Exchange Surfaces with Cells Throughout the BodyEvery cell in your body needs resources (O2 and Glucose) and needs to get rid of wastes (CO2 and Ammonia).All cells need to be in contact with the environment.Gastrovascular cavities containing nutrients and wastes bath all the cells of the organism.

CircularcanalMouthRadial canals5 cm(a) The moon jelly Aurelia, a cnidarian(b) The planarian Dugesia, a flatwormGastrovascularcavityMouthPharynx2 mmCirculatory system fluid, interconnecting vessels, and a muscular pump (heart)Open circulatory fluid (hemolymph) bathes the organs.Fluid is released around organs when the heart contracts, and floods back into vessels with valves when the heart relaxes.EX: arthropods and molluscsClosed circulatory fluid (blood) stays confined to vessels.Blood travel out of hearts ventricle (lower chambers) in arteries, back to hearts atria (upper chambers) in veins, and exchanges materials with cells in capillaries.EX: annelids, cephalopods, and all vertebrates

(a) An open circulatory systemHeartHemolymph in sinusessurrounding organsPoresTubular heartDorsalvessel(main heart)AuxiliaryheartsSmall branchvessels ineach organVentral vesselsBloodInterstitial fluidHeart(b) A closed circulatory systemSingle CirculationBony fish, rays and sharks2 chambers (1 atrium, 1 ventricle)Blood flows through the heard only once.A V artery gills body vein

(a) Single circulationArteryHeart:Atrium (A)Ventricle (V)VeinGillcapillariesBodycapillariesKeyOxygen-rich bloodOxygen-poor bloodDouble CirculationAmphibians, reptiles, mammals and birds.Blood goes to the heart twice, through 2 circulations.Pulmonary circuit blood travels from (right) heart to gas exchange tissueSystemic circuit blood travel from (left) heart to the body cells

AmphibiansReptiles (Except Birds)Pulmocutaneous circuitPulmonary circuitLungand skincapillariesAtrium(A)Atrium(A)LeftRightVentricle (V)SystemiccapillariesSystemic circuitSystemic circuitSystemic circuitSystemiccapillariesIncompleteseptumIncompleteseptumLeftsystemicaortaLeftRightRightsystemicaortaAAVVLungcapillariesLungcapillariesPulmonary circuitAAVVLeftRightSystemiccapillariesKeyOxygen-rich bloodOxygen-poor bloodMammals and Birds42.2 Coordinated Cycles of Heart Contraction Drive Double Circulation in Mammals

Pulmonary arteryRightatriumSemilunarvalveAtrioventricularvalveRightventricleLeftventricleAtrioventricularvalveSemilunarvalveLeftatriumPulmonaryarteryAorta

Superior vena cavaPulmonaryarteryCapillariesof right lungPulmonaryveinAortaInferiorvena cavaRight ventricleCapillaries ofabdominal organsand hind limbsRight atriumAortaLeft ventricleLeft atriumPulmonary veinPulmonaryarteryCapillariesof left lungCapillaries ofhead and forelimbsThe Mammalian HeartContraction phase heart is called systole.The relaxation phase is called diastole.Average cardiac output is 5L/min at a heart rate of 72 beats/min.The lub-dub sound is the sound of blood recoiling against closed atrioventricular valves and semilunar valves (respectively).A heart murmur occurs when the valves dont fully close, causing blood to backflow.

Atrial andventricular diastoleAtrial systole and ventricular diastoleVentricular systole and atrialdiastole0.1sec0.4sec0.3 sec213Maintaining the Hearts Rhythmic BeatSinoatrial (SA) node in the right atrium coordinates the contraction of the other heart cells (pacemaker).This impulse can be seen on an electrocardiogram (ECG)Atrioventricular (AV) node delays the impulse to the ventricles then sends it to have both contract at the same time.Controlled by sympathetic (quickens) and parasympathetic (slows) nervous system.

SA node(pacemaker)AVnodeBundlebranchesHeartapexPurkinjefibersECG1234PQRSTBlood PressureA beating heart generates high blood pressure, causing blood to flow from the heart to the arteries.Ventricular contraction causes systolic pressure.Elastic connective tissues expand and recoil to maintain blood pressure away from the heart once the ventricle relaxes (diastolic pressure).VasoconstrictionIncreases blood pressure due to artery walls constrictingCaused by physical or emotional stress resulting in nervous and hormonal response to release endothelin to smooth muscle.VasodilationDecreases blood pressure due to artery walls opening up (dilating) Caused by environmental or physical cues to release nitric oxide (NO).

Blood Pressure and GravityMeasured at same height as heart.Standing decreases blood pressure to the brain because it is further from the heart and working harder against gravity.Apply to long necked organisms (giraffes) need valves to slow blood flow when the neck is bend over to take a drink.

Blood pressure reading: 120/7012070SoundsstopSoundsaudible instethoscope120Arteryclosed123Capillary FunctionCapillaries are the sight of exchange with the interstitial fluid.Some molecules move via endo- and exocytosis.Some molecules (O2 and CO2) can diffuse across the endothelium.Blood pressure tends to drive fluid out of the capillaries.Proteins dispersed in the blood tend to drive fluid into the capillaries (osmotic pressure)Blood pressure is typically greater than osmotic pressure, particularly close to the arteriole.

INTERSTITIALFLUIDNet fluid movement outBloodpressureOsmoticpressureArterial endof capillaryDirection of blood flowVenous endof capillaryBody cellFluid Return by the Lymphatic SystemThe lymphatic system is a network of vessels and nodes that returns fluids, proteins and cells to the circulatory system.Lymph is the fluid lost by the capillaries.Vessels work similarly to veins (valves and muscle contractions)Lymph nodes filter lymph and house cells that attach pathogens (immune system).Found in the neck, armpits, and groin.Honeycomb of white blood cells that quickly divide when the body is infected.This causes them to swell and is why they are checked by doctors.

42.4 Blood Components Function in Exchange, Transport, and DefenseBlood Composition

Plasma 55%ConstituentMajor functionsWaterIons (bloodelectrolytes)SodiumPotassiumCalciumMagnesiumChlorideBicarbonateSolvent forcarrying othersubstancesOsmotic balance,pH buffering,and regulationof membranepermeabilityPlasma proteinsOsmotic balance,pH bufferingAlbuminFibrinogenImmunoglobulins(antibodies)ClottingDefenseSubstances transported by bloodNutrientsWaste productsRespiratory gasesHormonesSeparatedbloodelementsBasophilsNeutrophilsMonocytesLymphocytesEosinophilsPlateletsErythrocytes (red blood cells)56 million250,000400,000BloodclottingTransportof O2 andsome CO2Defense andimmunityFunctionsNumber per L(mm3) of bloodCell typeCellular elements 45%Leukocytes (white blood cells)5,00010,000Blood Clotting MechanismCoagulationsolid clot forms from liquid bloodA cascade of complex reactions converts inactive fibrinogen to fibrin, forming a clotA blood clot formed within a blood vessel is called a thrombus and can block blood flowHemophiliaresults when a mutation causes a change in any one of the proteins involved in the cascade

Cardiovascular DiseaseAtherosclerosisHardening of arteries by accumulating of fatty deposits due to high levels of low-density lipoprotein (LPL)Heart AttacksDamage or death of cardiac muscle tissue resulting from blockage of one or more coronary arteries.StrokesDeath of nervous tissue in the brain from ruptured or blocked arteries in the head.

Lumen of arterySmoothmuscleEndotheliumPlaqueSmoothmusclecellT lymphocyteExtra-cellularmatrixFoam cellMacrophagePlaque ruptureLDLCholesterolFibrous cap124342.5 Gas Exchange Occurs Across Specialized Respiratory SurfacesAir is less dense, viscous, and has a higher concentration of O2.These animals do not need to be very efficient breathersWater is more dense, viscous, and has a lower concentration of O2.These animals expend a lot of energy for gas exchange.Respiratory SurfacesMoistLarge surface area and thinSponges, cnidarians, and flatworms have body cells in direct contact with environment (diffusion).Earthworms and some amphibians use their skin.Fish use gillsInsects use tracheaOther vertebrates use lungsGills in Aquatic AnimalsOutfoldings of the body surface that are suspended in the water.Water must move across gills for gas exchange (ventilation)Paddle-like appendages that drive a current of water over the gillsCilia move water over gillsTaking in and ejecting water over gillsSwimming and opening of mouth for water to pass through the pharynx, over the gills, and out of the body.Countercurrent exchange for diffusion of gases and heat.

GillarchO2-poor bloodO2-rich bloodBloodvesselsGill archOperculumWaterflowWater flowBlood flowCountercurrent exchangePO (mm Hg) in water2150PO (mm Hg)in blood2120906030140110805020Net diffu-sion of O2LamellaGill filamentsTracheal Systems in InsectsAir tubes that run throughout the body.Tracheae open to the outside which branch into smaller tubes which come close to every cell.Gas is exchanged by diffusion across the epithelium.

TracheolesMitochondriaMuscle fiber2.5 mTracheaeAir sacsExternal openingTracheaAirsacTracheoleBodycellAirLungsLocalized organ which needs the circulatory system to go to cells for gas exchange.Air flows:Nose/mouthPharynxLarynx (vocal cords)Epiglottis closes esopohogousTrachea (windpipe)2 bronchi (1 to each lung)Bronchioles (cilia/mucous trap dirt)Alveoli (gas exchange)Leukocytes patrol and keep cleanSmoking can overwhelm

PharynxLarynx(Esophagus)TracheaRight lungBronchusBronchioleDiaphragm(Heart)CapillariesLeftlungDense capillary bedenveloping alveoli (SEM)50 mAlveoliBranch ofpulmonary artery(oxygen-poorblood)Branch ofpulmonary vein(oxygen-richblood)TerminalbronchioleNasalcavity42.6 Breathing Ventilates the LungsHow an Amphibian BreathesPositive pressure breathing forces (pushes) air down the trachea.The lungs elastically recoil, forcing air out (exhale)How a Bird BreathesAir moves in 1 direction across gas exchange surface.Fresh air doesnt mix with old air.

Anteriorair sacsPosteriorair sacsLungs1 mmAirflowAir tubes(parabronchi)in lungAnteriorair sacsLungsSecond inhalationFirst inhalationPosteriorair sacs32414312Second exhalationFirst exhalationHow a Mammal BreathesNegative pressure breathing pulls air into lungs.The rib muscles and diaphragm contract, creating a negative pressure in the thoracic cavity. This causes air to rush into the lung (high to low pressure).When they relax, air is pushes out.Tidal volume is the average volume of air inhaled whereas vital capacity is the maximum volume. Residual volume is air that is left in the lungs after exhalation.

Rib cageexpands.Airinhaled.Airexhaled.Rib cage getssmaller.12LungDiaphragmControl of BreathingInvoluntary action controlled by the medulla oblongata. Uses pH as an indicator of CO2 concentrations of the surrounding tissues .CO2 reaction with H2O of CS fluid creating carbonic acid. This dissociates into a bicarbonate ion and H+.

Homeostasis:Blood pH of about 7.4CO2 leveldecreases.Stimulus:Rising level ofCO2 in tissueslowers blood pH.Response:Rib musclesand diaphragmincrease rateand depth ofventilation.CarotidarteriesAortaSensor/control center:Cerebrospinal fluidMedullaoblongata42.7 Adaptations for Gas Exchange Include Pigments that Bind and Transport GasesO2 transport proteins bound to a metal; called pigments because they have distinctive colors.Hemoglobin4 polypeptide chains each with a heme group attached to iron.Can carry up to 4 O2 When 1 subunit binds to O2 the others change shape to become more susceptible to O2.When pH drops, it releases more O2 (Bohr shift).

IronHemeHemoglobin

(b) pH and hemoglobin dissociationPO (mm Hg)2020406080100020406080100Hemoglobinretains lessO2 at lower pH(higher CO2concentration)pH 7.2pH 7.4O2 saturation of hemoglobin (%)Carbon Dioxide TransportCO2 is not directly transported in blood.It dissociated into bicarbonate and H+H+ attaches to hemoglobinBicarbinate travels in plasmaIn lungs, it recombines to for CO2 again.

Body tissueCapillarywallInterstitialfluidPlasmawithin capillaryCO2 transportfrom tissuesCO2 producedCO2CO2CO2H2OH2CO3HbRedbloodcellCarbonicacidHemoglobin (Hb)picks upCO2 and H+.H+HCO3BicarbonateHCO3HCO3To lungsCO2 transportto lungsHCO3H2CO3H2OCO2H+HbHemoglobinreleasesCO2 and H+.CO2CO2CO2Alveolar space in lungRespiratory Adaptations of Diving MammalsApneatic mammalsStores more O2 in blood or attached to myoglobin proteins in muscles for later use.Turn off unnecessary organs and shunt blood away from them.

Putting the Two Together

Exhaled airInhaled airPulmonaryarteriesSystemicveinsSystemicarteriesPulmonaryveinsAlveolarcapillariesAlveolarspacesAlveolarepithelialcellsHeartSystemiccapillariesCO2O2Body tissue(a) The path of respiratory gases in the circulatory systemCO2O281237645