The proportion of the left ventricular volume that is pumped out of the heart during systole is the:
A. ejection fraction
For a resting potential in a cardiac cell to exist, there must be an:
D. adequate number of potassium ions inside the cell and sodium ions outside the cell
The valve between the right atrium and right ventricle is the _____ valve.
C. tricuspid
Which of the following is most characteristic of right heart failure?
C. JVD, peripheral edema, and hepatic engorgement
The intrinsic firing rate of the AV node is _____ to _____ times per minute.
C. 40 to 60
Which of the following items is most likely to interfere with the function of an implanted cardiac pacemaker?
A. magnet
The amount of resistance that must be overcome by the left ventricle during systole is called:
A. afterload
The first phase of the cardiac cycle is:
C. diastole
Release of acetylcholine at the neuroeffector junction would result in a(n):
C. negative chronotropic effect
Parasympathetic innervation of the heart occurs via the:
D. vagus nerve
You have administered a medication to a patient, resulting in a decreased speed of cardiac impulse conduction. This drug is most accurately described as having a _____ effect.
B. negative dromotropic
When the ECG paper is traveling at the standard rate of 25 mm/sec, a large box in the horizontal direction equals:
D. 0.20 seconds
On a properly calibrated ECG machine, 1 mV is equivalent to a height of _____ boxes.
A. ten small
Which of the following is the correct sequence of cardiac electrical activity?
1 AV node
2 internodal pathways
3 bundle of His
4 SA node
5 Purkinje fibers
6 bundle branches
B. 4, 2, 1, 3, 6, 5
The SA and AV nodes are often supplied by both the _____ and _____ arteries.
C. right coronary, circumflex coronary
A patient's ECG shows regular RR intervals of 0.48 seconds, a PR interval of 0.12 seconds, and a QRS of 0.08 seconds. This best fits the criteria for:
B. sinus tachycardia
Beta-blockers generally have which of the following effects?
A. decreased myocardial contractility
Which of the following occurs during depolarization of a cardiac cell?
A. the cell becomes relatively more positively charged
The total duration of ventricular depolarization is represented by the _____ on the ECG.
D. QT interval
Stroke volume x heart rate x peripheral vascular resistance =
D. blood pressure
Blood entering the left atrium arrives via the:
B. pulmonary vein
Typical stroke volume is about _____ of the volume of the left ventricle.
C. two-thirds
Your patient is found sitting on the edge of the bathtub with cool, diaphoretic skin. She states she became lightheaded and nearly "passed out" while vomiting. Your cardiac monitor shows a sinus bradycardia at a rate of 48. Which of the following is most likely?
C. increased parasympathetic tone
There are 15 small boxes between R waves on an ECG tracing. What is the heart rate?
