18. The Heart

Which medication reduces the workload of the heart by treating abnormal heart rhythms?

The heart contracts because of an electrical impulse. Where in the heart does this impulse start?

What ensures the movement of blood in one direction through the heart?

Which structure of the cardiac conduction system acts as the pacemaker of the heart?

Which of the following factors gives the myocardium its high resistance to fatigue?

What sequence describes the flow of electrical impulses in the heart?

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

In the normal electrical conduction system of the heart, the electrical impulse normally begins at which structure?

The cardiac muscle receives its supply of oxygenated blood by which of the following mechanisms?

What causes the semilunar valves to open during the cardiac cycle?

What is the formula for calculating heart rate using the QRS complexes on an ECG?

What is the correct order of impulse conduction through the conduction system in the heart?

Which of the following is true about the heart's function in the circulatory system?

The role of the atrioventricular node (AV node) is to __________.