What is most likely to happen if the SA node suddenly stops generating the impulse?
1. The heart will stop.
2. The ventricles will contract, but the atria will stop.
3. Another part of the heart, possibly the AV node, will become the pacemaker.
4. The atria will keep contracting, but the ventricles will stop.

Identify the correct statement regarding the cardiac muscle:
1. Cardiac muscle does not have sarcoplasmic reticulum.
2. Cardiac muscle has a plateau phase in repolarization called the plateau phase.
3. Cardiac muscle has a shorter refractory period than skeletal muscle.
4. Depolarization of cardiac muscle occurs when ${\mathrm{K}}^{+}$ and ${\mathrm{Na}}^{+}$ diffuse into the cell.

A slower heart rate or bradycardia would most likely be the result of:
1. ectopic action potentials in the atria
2. damage to the tricuspid valve
3. excessive sympathetic stimulation
4. excessive parasympathetic stimulation

The location of the human heart is most accurately described as:

Pericardial fluid is the serous fluid secreted by the serous layer of the pericardium into the pericardial cavity and it serves to:
1. reduce friction between the pericardial membranes.
2. lubricate the heart valves.
3. replace any blood that is lost.
4. provide oxygen and nutrients to the endocardium.

All cardiac veins empty into the ______, which then empties into the ______.
1. coronary sinus; left atrium
2. coronary sinus; right atrium
3. great cardiac vein; right atrium
4. great cardiac vein; left atrium

The right ventricle of the heart pumps blood into the:

What exactly is an auricle?
1. a sphincter present in an arteriole.
2. an extension of the atrial wall.
3. part of a heart valve.
4. part of nodal tissue of the heart.

A thrombus in the pulmonary trunk would interfere with blood:
1. being distributed to the systemic circulation.
2. picking up oxygen in the lungs.
3. getting into the right atrium.
4. leaving the left ventricle.

What separates the atria from the ventricles so that the atrial impulse does not spill onto the ventricles?