Inotropic agents affect A) heart rate, b) contractility D) depolarization. What
ID: 170532 • Letter: I
Question
Inotropic agents affect A) heart rate, b) contractility D) depolarization. What do pacemaker cell action potentials lack? A) threshold B)plateau phase C) depolarization D) repolarization What best describes the Frank-Starling law? A) The Frank-Starling law states that the greater the stroke volume, the greater the heart rate. B) The Frank-Starting law states that the greater the volume of blood discharged from the heart, the greater the pressure required to discharge the blood. C) The Frank-Starling law states that the more the ventricular muscle cells are stretched, the more forcefully they contract. D) The Frank-Starting law states that the slower the heart rate, the greater the cardiac output. Which of the below valves A) Tricuspid valve B) Bicuspid valve C) Pulmonary valve D) Aortic valve E) Pulmonary veinExplanation / Answer
kindly please post only one question. Here i am going to answer number 22.
Sinoatrial node(SA node) is primary pacemaker of heart other than this Atrioventricular node and Bundle of His are secondary pacemaker cells,which generates action potential which helps in contraction of heart usually known as heart pump.
Action potential is an electrical stimulation created around the membrane of cardiomyocytes due to ion exchange.
Pacemaker cell action potential comprises of:
1.Funny current or pacemaker current where slow sodium channels depolarizes Transmembrane potential (TMP)above 60 mV.
2.Threshold potential where TMP is -40mV and opening of calcium channels depolarizes cells to 0mV
3.Plateau phase where potassium channels counteract the calcium channels and return the TMP to - 60mV.
Therefore answer for your question will be option 'D' i.e.repolarization.
Thank you