Extrasystole and compensatory pause oftoad heart Teaching Center for Experimental Medicine
Extrasystole and compensatory pause of toad heart Teaching Center for Experimental Medicine
Extrasystole a premature cardiac contraction that is independent of the normal rhythm and arises in response to an impulse outside the sinoatrial node. AM八f 八AA /个 Compensatory pause The pause following an extrasystole,when the pause is long enough to compensate for the prematurity of the extrasystole; the short cycle ending with the extrasystole plus the pause following the extrasystole together equal two of the regular cycles
Extrasystole a premature cardiac contraction that is independent of the normal rhythm and arises in response to an impulse outside the sinoatrial node. Compensatory pause The pause following an extrasystole, when the pause is long enough to compensate for the prematurity of the extrasystole; the short cycle ending with the extrasystole plus the pause following the extrasystole together equal two of the regular cycles
ERP:Effective refractory period 20- RRP:Relative refractory period -20 mV -40 ERP 60 -80 -100」 100ms A:Action potential B:Mechanical contraction Significance: The cardiac muscle is refractory to any stimulus during the contraction phase and thus tetanus cannot be produced in cardiac muscle. 2. The cardiac muscle can relax and get filled up with blood and then contract to pump out the blood
ERP: Effective refractory period RRP: Relative refractory period Significance: 1. The cardiac muscle is refractory to any stimulus during the contraction phase and thus tetanus cannot be produced in cardiac muscle. 2. The cardiac muscle can relax and get filled up with blood and then contract to pump out the blood
Aim: 1.To investigate the changes of excitability in a cardiac cycle. 2. To understand the significance of long effective refractory period of heart
Aim : 1. To investigate the changes of excitability in a cardiac cycle. 2. To understand the significance of long effective refractory period of heart
Experimental manubrium sterni Procedure 1.Dissection Procedures Destroy the brain and spinal cord of a toad and fasten it to a board,ventral side up; Use scissors to make a longitudinal incision on chest wall to expose the heart
manubrium sterni 1.Dissection Procedures : • Destroy the brain and spinal cord of a toad and fasten it to a board, ventral side up; • Use scissors to make a longitudinal incision on chest wall to expose the heart ; Experimental Procedure