Fig. 41-14: Hormonal control of digestionSecretinand CCKStomachGallbladderLiver+Duodenum ofsmall intestineBileGastrinSecretinPancreasCCKCCKKeyStimulationInhibition+–+++–Amino acids or fatty acidsin the duodenum trigger therelease of cholecystokinin(CCK), which stimulates therelease of digestive enzymesfrom the pancreas and bilefrom the gallbladder.Secretin stimulates the pancreas to release sodium bicarbonate, which neutralizes acid chyme from the stomach.Gastrin circulates via the bloodstream back to the stomach, where it stimulates production of gastric juices.When chyme rich in fatsenters the duodenum,secretin and CCK inhibitperistalsis and acidsecretion by the stomach,thereby slowing digestion.HeartHemolymph in sinusessurrounding organsHeartInterstitialfluidSmall branch vesselsIn each organBloodDorsal vessel(main heart)Auxiliary hearts Ventral vessels(b) A closed circulatory system(a) An open circulatory systemTubular heartPoresFig. 42-3: Open and Closed Circulatory systemsArteryVentricleAtriumHeartVeinSystemic capillariesSystemiccirculationGillcirculationGill capillariesFig. 42-4:SingleCirculationin fishesAmphibiansLung and skin capillariesPulmocutaneouscircuitAtrium (A)Ventricle (V)Atrium (A)SystemiccircuitRightLeftSystemic capillariesReptiles (Except Birds)Lung capillariesPulmonarycircuitRightsystemicaortaRightLeftLeftsystemicaortaSystemic capillariesAAVVSystemic capillariesPulmonarycircuitSystemiccircuitRight LeftAAVVLung capillariesMammals and BirdsFig. 42-5: Double Circulation in VertebratesFig. 42-6:The MammalianCardiovascularSystemSuperiorvena cavaPulmonaryarteryCapillariesof right lung3738924115110AortaPulmonaryveinRight atriumRight ventricleInferiorvena cavaCapillaries ofabdominal organsand hind limbsPulmonaryveinLeft atriumLeft ventricleAortaCapillariesof left lungPulmonaryarteryCapillaries ofhead andforelimbsFig. 42-7: The Mammalian HeartPulmonary arteryRightatriumSemilunarvalveAtrioventricularvalveRightventricleLeftventricleAtrioventricularvalveLeftatriumSemilunarvalvePulmonaryarteryAortaSignals spreadthroughoutventricles.4PurkinjefibersPacemakergenerates wave ofsignals to contract.1SA node(pacemaker)ECGSignals aredelayed atAV node.2AVnodeSignals passto heart apex.3BundlebranchesHeartapexFig. 42-9: Control of Heart RhythmFig. 42-8:Cardiac CycleSemilunarvalvesclosed0.4 secAVvalvesopenAtrial andventriculardiastole120.1 secAtrial systole;ventriculardiastole30.3 secSemilunarvalvesopenAV valvesclosedVentricular systole;atrial diastole(courtesy of Patricia
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