_____________ is the most superficial layer enclosing the heart.
C. Parietal pericardium
Pericardial fluid is found between
B. the parietal and visceral membranes.
The ________________ performs the work of the heart.
A. myocardium
The tricuspid valve regulates the opening between
C. the right atrium and right ventricle.
Oxygen-poor blood passes through
C. the right AV (tricuspid) valve and pulmonary valve.
Opening and closing of the heart valves is caused by
A. breathing.
B. gravity.
C. valves contracting and relaxing.
D. osmotic gradients.
E . pressure gradients.
E . pressure gradients.
After entering the right atrium, the furthest a red blood cell can travel is the
A. superior vena cava.
Obstruction of the ___________ will cause a more severe myocardial infarction (MI) than the obstruction of any of the others.
E . circumflex branch
B. left coronary artery (LCA)
Cardiac muscle shares this feature with skeletal muscle.
A. cardiac muscle fibers have striations
The ________________ is the pacemaker that initiates each heart beat.
B. sinoatrial (SA) node
Which of these is not part of the cardiac conduction system?
D. the tendinous cords (TC)
These are features of cardiac muscle fibers except
C. they have about the same endurance as skeletal muscle fibers.
This is the correct path of an electrical excitation from the pacemaker to a cardiocyte in the left ventricle (LV).
C. sinoatrial (SA) node → atrioventricular (AV) node → atrioventricular (AV) bundle → Purkinje fibers → cardiocyte in LV
The pacemaker potential is a result of
B. Na+ inflow.
Cells of the sinoatrial node ____________ during the pacemaker potential.
C. depolarize slow
Any abnormal cardiac rhythm is called a(n)
B. arrhythmia.
If the sinoatrial (SA) is damaged, the heart will likely beat at
E. 40 to 50 bpm.
The _______________ provides most of the Ca2+ needed for myocardial contraction.