The contractile cardiac muscle fibers of the myocardium behave as a single, coordinated unit called a __________.
functional syncytium
The inferior vena cava brings blood from the lower regions of the body and empties into the __________.
right atrium
The role of the atrioventricular node (AV node) is to __________.
slow down impulses so that the atria can contract to fill the adjacent ventricles with blood
Into which chamber of the heart do the pulmonary veins deliver blood?
left atrium
What is the correct sequence of electrical current flow through the heart wall?
SA node, AV node, AV bundle, right and left bundle branches, subendocardial conducting network
From the perspective of blood returning from the systemic circuit, identify the correct sequence of blood flow through the chambers of the heart.
right atrium, right ventricle, lungs, left atrium, left ventricle
The lining of the heart chambers is called the __________.
endocardium
The structure just deep to the fibrous pericardium is the __________.
parietal layer of the serous pericardium
Which valve is most often faulty in the heart?
the mitral, or bicuspid, valve
The P wave of an electrocardiogram represents __________.
atrial depolarization
The absolute refractory period refers to the time during which __________.
the muscle cell will not respond to a stimulus of any strength
What part of the heart is considered the systemic circuit pump?
the left ventricle
The normal pacemaker of the heart is the __________.
SA node
Freshly oxygenated blood is delivered to the __________, and then it passes into the __________ to be pumped to the body tissues (systemic circuit).
left atrium; left ventricle
What factor gives the myocardium its high resistance to fatigue?
a very large number of mitochondria in the cytoplasm
The most muscular chamber of the heart is the __________.
left ventricle
The coronary arteries arise from the __________.
aorta
When the mitral valve closes, it prevents the backflow of blood from the __________.
left ventricle into the left atrium
The second heart sound (the “dup” of “lub-dup”) is caused by the __________.
closure of the semilunar valves
The __________ are attached to the AV valve flaps.
chordae tendineae
The noncontractile cardiac muscle cells that initiate their own depolarization and cause depolarization of the rest of the heart are called __________.
pacemaker cells
The __________ nerve carries parasympathetic fibers to the sinoatrial (SA) node.
vagus
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