In cardiac autorhythmic pacemaker cells, how does parasympathetic stimulation make it more difficultfor an action potential to occur?

Why does the cardiac muscle have a longer absolute refractory period compared to skeletal muscle?

in the cardiac His-purkinje system , why do more polarized cells conduct electrical signals more quickly ?

Using information provided in the text, calculate the power generated by the right ventricle during (a) restful state; blood flow 5 liter/min, and (b) intense activity; blood flow 25 liter/min.

Jake suffers from a mutation in voltage-gated calcium channels found in theirSA node. This mutation lowers the threshold at which the channels open.What effect do you think this mutation will have on his heart rate compared tosomeone with a normal threshold? Why does this effect occur?

Atrial fibrillation can be caused by wandering re-entrant circuits.  What does this mean?

Knowing that a patient with chronic heart failure is using digoxin (digitalis) for more than 1 year, what effect has this treatment on the distribution of ions across the membrane of cardiac muscle cells? What is effect will be of digitalis on cardiac contractility? What is an inotropic effect? How does digitalis help to treat patients with heart failure?

In which of the following situations is calcium moving through a channel in the pacemaker membrane driven by concentration but against charge? O during the repolarization phase of the action potential, just before the channel closes O during the depolarization phase of the action potential, just after the channel opens O never O at all times that sodium is moving through the membrane O during the repolarization phase of the action potential, just after the channel opens O during the depolarization phase of the action potential, just before the channel closes O during the pacemaker potential, just before the funny channel closes

Explain alpha1/2 and beta1/2 receptors in the heart