CARDIOVASCULAR FUNCTION In Rana pipiensANNOUNCEMENTSSlide 3CARDIOVASCULAR PHYSIOLOGYFROG CARDIOVASCULAR PHYSIOLOGYFROG CARDIOVASCULAR PHYSIOLOGYANATOMICAL FEATURES OF THE AMPHIBIAN HEARTFROG CARDIOVASCULAR PHYSIOLOGYSlide 9Slide 10Slide 11Slide 12AUTONOMIC PATHWAYSSlide 14FROG CARDIOVASCULAR PHYSIOLOGYEXTRINSIC FACTORS: IDENTIFICATION OF AN UNKNOWNSlide 17Slide 18CONTRACTILITYSTARLING’S LAW OF THE HEARTSlide 21Slide 22CARDIOVASCULAR FUNCTION In Rana pipiensBiology 305 LaboratoryANNOUNCEMENTSOral & Poster Presentation:Researched, written, prepared & presented as groupYou must choose ONE lab from the semester: –Included labs:»Crayfish MRO, Sciatic Nerve, G. Muscle, Cardiovascular and Urinalysis labsDetail to be given in handout in lab next weekANNOUNCEMENTSOral & Poster Presentations:Choose your lab carefullyLet TA know your choice ASAPMaximum of two groups per lab!Maximum of three individuals per groupCARDIOVASCULAR PHYSIOLOGYLeopard Frog (Rana pipiens): Use of force transducer to measure relative force and frequency of contraction of frog heartNote: heart is myogenic…no stimulus necessary!FROG CARDIOVASCULAR PHYSIOLOGYThe CV System:CV system tied to respiratory system•Functions in gas exchange & transport of nutrients and waste productsFROG CARDIOVASCULAR PHYSIOLOGYAmphibian Heart:Heart has three chambers: One cardiac cycle:•O2-deficient blood enters R.atrium•Blood enters ventricle •Blood pumped to lungs•Blood returns to heart via L. atrium•Blood enters ventricle where it mixes with O2-defficient blood•Blood is ejected into bodyANATOMICAL FEATURES OF THE AMPHIBIAN HEARTHeart is myogenicSinus Venosus:–Region of pacemaker cells–Analogous toFROG CARDIOVASCULAR PHYSIOLOGYLeopard Frog (Rana pipiens): May observe both atrial & ventricular contraction–Upward deflection on traceFROG CARDIOVASCULAR PHYSIOLOGYRegulation of Heart Rate Represents Balance: –Intrinsic Factors:–Extrinsic Factors:FROG CARDIOVASCULAR PHYSIOLOGYIntrinsic Factors:Innervations of the Heart:–Autonomic Nervous System (ANS) has two subdivisions that influence HR (& force of contraction)FROG CARDIOVASCULAR PHYSIOLOGYDivisions of ANS:Sympathetic DivisionParasympathetic DivisionThe two divisions workFROG CARDIOVASCULAR PHYSIOLOGYParasympathetic Division–Releases Sympathetic Division–ReleasesAUTONOMIC PATHWAYSSympathetic Pathway:<<TargetTissue<<TargetTissue Parasympathetic Pathway: = ADRENERGIC = CHOLINERGICFROG CARDIOVASCULAR PHYSIOLOGYEffect of Neurotransmitters (neurohormone):NE/Epi –Binds to receptors on heart, speeding up HR Ach –Binds to receptors, slowing down HRFROG CARDIOVASCULAR PHYSIOLOGYExtrinsic Factors:Agonists:–Molecules that combine with receptor–Molecules thatAntagonists:–Molecules thatEXTRINSIC FACTORS: IDENTIFICATION OF AN UNKNOWNTesting Pharmacological Agents of Unknown OriginIf an unknown agent increases HR, two mechanisms are possible: –Test for antagonist:FROG CARDIOVASCULAR PHYSIOLOGYRelative Force of Contraction:Measured indirectly through •Measured inStroke Volume =Influenced by:•Intrinsic factors: •Extrinsic factors:CHANGES IN FORCE OF CONTRACTION & STROKE VOLUMEStarling’s Law of the Heart :•Heart muscle contracts with greater force when distendedCONTRACTILITYContractility (Inotropy):Ability of a cardiac muscle fiber to contract•Agents that increase contractility are called•Agents that decrease contractility are calledSTARLING’S LAW OF THE HEARTForce ofContraction or StrokeVolume (ml) End Diastolic Volume (ml)NormalStretch of Myocardial Cells Causes Greater Force of Contraction *Contractile Force As A Function of EDV^ Some chemical agents can affect contractile force irrespective of level of stretchCHANGES IN FORCE OF CONTRACTION & STROKE VOLUMEContractility (Inotropy):•In mammals, NE/EPI typically increase contractility•Results in increased force, even though increase in HRFROG CARDIOVASCULAR PHYSIOLOGYSome Hints For Lab:Avoid Contamination: label all beakers & pipettes!!!Apply NE, Cold Ringers and Ach to heart and observe response (frequency/amplitude) on computerApply Ringer’s solution often–Especially between each treatment Take baseline readings BEFORE addition of each treatment!Mark the record EVERY TIME you add anything to the heart After running agents of known origin, consult with group members or your TA on how to test the identity of an unknown