The cells of the conducting system differ from the contractile cells of the heart in that (a) conducting cells are larger and contain more myofibrils, (b) contractile cells exhibit pacemaker potentials, (c) contractile cells do not normally exhibit autorhythmicity, (d) both a and b are correct.

The normal pacemaker of the heart is the __________.

The __________ nerve carries parasympathetic fibers to the sinoatrial (SA) node.

a. Name the elements of the intrinsic conduction system of the heart in order, beginning with the pacemaker.b. What is the important function of this conduction system?

The activity of the heart depends on intrinsic properties of cardiac muscle and on neural factors. Thus,a. vagus nerve stimulation of the heart reduces heart rate,b. sympathetic nerve stimulation of the heart decreases time available for ventricular filling,c. sympathetic stimulation of the heart increases its force of contraction,d. all of the above.

The autonomic centers for cardiac function are located in (a) the myocardial tissue of the heart, (b) the cardiac centers of the medulla oblongata, (c) the cerebral cortex, (d) all of these structures.

Trace the normal pathway of an electrical impulse through the conducting system of the heart.

What effect does sympathetic stimulation have on the heart? What effect does parasympathetic stimulation have on the heart?

What role do the chordae tendineae and papillary muscles play in the normal function of the AV valves?