医学机能实验学报告蛙心灌流英文.docx

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1、Laboratory Report本组承诺：本实验报告原创，绝无抄袭! 组员：Effects of chemical substances on the activity of theisolated toad heartPurpose To observe the effects of three ions (sodium,potassium,calcium) and two chemical substances (acetylcholine and adrenaline) on the activity of the toad heart in vitro.【Animal Toad.【M

2、ethod 1 .Preparation of the isolated heartTake a toad, after destorying its brain and spinal cord, fix it on the toad plate on back, open the thoracic cavity, cut pericardium to expose the heart. Then, put one line under aorta making a slipknot at the superior extremity of the left aorta,is used to

3、tow when intubation. Shear a reversed “V shaped incision with ophthalmological scissors at root of left aorta,insert a proper cannula of toad heart that contains Ringers solution into the artery cone from the cut position.Then make a dead knot. Hold up the cannula gently to raise heart, make a ligat

4、ion at the boundary of the venous sinus and the vena cava. Finally, cut off aortas and the vena cava, dissociate the heart from the toad.2 .Apparatus installmentAt first,clamp the canula with a wooden tube clip, then the wooden tube clip is fixed on the iron bracket by a double cave clamp.Clamp the

5、tip of the heart at ventricle diastole with a toad heart clip that is linked with a long line in the other end, then link the line to the adaptive bridge in the tension transducer. Regulate the position of the pulley so that the tensility of line is appropriate.3 .Observation items(1) .Record the no

6、rmal curve of the relaxation and constriction of theisolated heart.(2) .After the Ringers solution in cannula is all replaced by 0.65% Nacl, observe the change of the heartbeat.(3) .Take out the Nacl, wash it several times repearedly with fresh Ringers solution.When the heartbeat recovers to normal

7、add 2%Cach 2 drops to the Ringers solution in the cannula ,observe the change of the heartbeat.(4) .Take out the Ringers solution including Cack, wash it several times repearedly with fresh Ringers solution.After the curve recover to normal, add 1% KCL 2 drops in the Ringers solution in the cannula

8、,observe the change of the heartbeat.(5) .Take out the Ringers solution including Kcl, wash it several times repearedly with fresh Ringers solution.After the curve recover to normal, add 1:1000 adenaline 2 drops in the Ringers solution in the cannula ,observe the change of the heartbeat.(6) . .Take

9、out the Ringers solution including adenaline, wash it several times repearedly with fresh Ringers solution.After the curve recover to normal, add 1:1000 ACh 2 drops in the Ringers solution in the cannula ,observe the change of the heartbeat.【Result Contraction scopeContraction frequencynormalK+Ca2+N

10、a+ADTTAChJJThe image is in the last.Discussion l.The normal heart rhythm activities require a suitable environment, changes in the environment has a direct impact on the normal activity of the heart. This experiment in frog heart of perfusion fluid to join some of the material change in the environm

11、ent of cardiac activity, observe the changes in cardiac events.2.Cardiac muscle cells classificationContractili tyExcitabili tyConductivi tyautorhythmic itynon-autorhyth mic cellHasHasHasDoesnt haveautorhythmic cellDoesnt haveHasHasHas3. Fast reaction cell (Atria, ventricular, Purkinje cells): mainl

12、y consists of sodium channel is activated, Na fast flow triggered action potential.Slow reaction cell (sinus cells, atrioventricular junction cell): mainly by slow calcium channel is activated, Ca raises action potentials in the stream, go to the very slow4. Myocardial cell physiological characteris

13、tics:(1) Electrophysiological characteristics: self-discipline, excitability, conductive(2) Machinery physiological characteristics: shrinkage5.Factors affecting cardiac cell excitability (ventricular myocytes)Impact factor of cardiomyocyte self-discipline (sinus cells)Impact myocardial cell conduct

14、ive factors (atrioventricular junction cells)1 . State of Na channel2 .Difference Resting potential level and threshold potential1 . Depolarization speed of 4 phase2 .Difference between maximum bipolar voltage level and thresholdl.diamete2.depolarization amplitude and speed of 0 phase3.The excitabil

15、ity of adjacent parts of the filmMyocardial cell excitation-contraction coupling processes required by the Ca2+ to transit from the extracellular fluid, excitement, cell membranes Ca2+ channel, therefore: extracellular Ca2+ concentration tcell excited inner flow Ca2+ tmyocardial contractilityt ,and

16、vice versa.6. 1%KC1Moderate and high potassium:Extracellular K +, K+ and Ca2+ in a competitive inhibition of cell-membraneK+ inhibitors on Ca2+ transportenter theintracellular Ca2+ Icardiac excitation-contraction with theprocess of weakeningmyocardial contractility I(1) t K+K+ concentration gradient

17、 reduces between inside andoutsideresting potential absolute value decreaseexcitatoryt(2) t K+cell membrane permeability increases on K+K+channel inactivating speed Iautomatic depolarization speed1autorhythmicity !(3) t K+cell membrane permeability increases on K+K+outflow increasemaximum repolariza

18、tion potential fautorhythmicity !(4) t K+inhibition of internal flow by Ca2+depolarizationamplitude andspeed of 0 phase reduceconductivity lower.Severe high potassium:K+ f tRP INa+ channel inactivationexcitatorylose.7. 2%CaCl2Na+ and Ca2+ in outer membrane have competitive inhibition Concentration o

19、f extracellular Ca2+ fCa2+ flow f when cellsexcitemyocardial contractility tFast reaction cell: high Ca2+inhibit Na+ inner flow0 periodDepolarisation speed and magnitude downwardconductivity ISlow reaction cell: high Ca2+Ca2+ enter into cells easily, Ca2+flow increase0 period Depolarisation speed in

20、creaseconductivity f 8. 0. 65%NaCIExtracellular Ca2+ 1Ca2+ flow X in 2 phaseCytosolicCa2+ concentration 1myocardial contractility 1Ca2+ 1Ca2+ inner flow reduction depolarisation slows in8. phaseconductive 1Ca2+ 1Ca2+ is not easy to enter the cellsautomaticdepolarization speed is slow in 4 phaseautor

21、hythmicity X9.ADAdrenaline conbines myocardial cell membrane of B -1 receptors - 一 myocardial cells and sarcoplasmic reticulum membrane permeability of Ca2+ increasessarcoplasmic Ca2+ concentrationincreases myocardial contractility T .lO.AChAcetylcholine conbines M receptor in myocardial cell membra

22、ne 一myocardial cell membrane permeability of K channelpromoting T K+ outflow(1) Sinoatrial node cells K+ outflow T when cells repolarizemax bipolar voltage level Tautorhythmicity 1(2) K+ outflow T when cells repolarize 2 and 3 phase of APshorterCa2+ into cells 1myocardial contractilityl(3) Acetylcho

23、line can inhibit Ca2+ channel directly Ca2+channel flow 1myocardial contractility，.Conclusion 1 .Infusion containing potassium ions, with special attention to detect the concentration of potassium ions.2 . If the toad!s heart beat weak, AD can be used to enhance the heart beat.3 .Control various ions concentration, AD and ACh volume to adjust the bodys internal environment to maintain homeotasis.