Which is TRUE about the function of the aortic valve?
A. It prevents the backflow of blood into the aorta during ventricular diastole.
B. It prevents the backflow of blood into the left ventricle during ventricular diastole.
C. It prevents the backflow of blood into the left ventricle during ventricular ejection.
D. It prevents the backflow of blood into the aorta during ventricular ejection.
E. Its closure causes the first heart sound.
(
Question 2) Which occurs during isovolumetric ventricular contraction?
A. Rapid filling of the ventricles occurs.
B. No blood enters or leaves the ventricles.
C. The maximum volume of blood is ejected.
D. Ventricular pressure reaches its maximum value of the cardiac cycle.
E. The pressure in the ventricles decreases while the pressure in the atria increases.
(
Question 3) What is indicated by a heart murmur detected between the first and second heart sounds?
A. insufficiency of a semilunar valve or stenosis of an AV valve
B. insufficiency of an AV valve or stenosis of a semilunar valve
C. heart failure
D. AV nodal conduction block
E. a myocardial infarction
(
Question 4) Which of the following statements about the cardiac cycle is TRUE?
A. The duration of systole is greater than that of diastole in a subject at rest.
B. During isovolumetric ventricular relaxation, blood flows from the atria into the ventricles.
C. Closure of the atrioventricular valves occurs at the onset of ventricular systole.
D. The QRS complex occurs at approximately the same time as the closure of the semilunar valves.
E. The first valves to go from closed to open after the atrial kick are the atrioventricular valves.
(
Question 5) Which of the following statements regarding the cardiac cycle is TRUE?
A. The AV valves are open during mid-to-late diastole.
B. The aortic valve is open during isovolumetric ventricular contraction.
C. The first heart sound is caused by the closing of the semilunar valves.
D. The dicrotic notch is a result of closure of the AV valves.
E. Closure of the AV valves occurs when the ventricles reach end-systolic volume.
(
Question 6) Which of the following statements about the refractory period of neuronal or muscle membranes is TRUE?
A. In nerve cells, the absolute refractory period coincides with the period of increased K+ permeability.
B. In skeletal muscle cells, the absolute refractory period lasts about as long as the twitch.
C. In ventricular cells, the absolute refractory period coincides with the period of increased Na+ and Ca2+ permeability.
D. The relative refractory period in neuronal membranes lasts about the same length of time as the absolute refractory period in cardiac muscle cell membranes.
E. The refractory period in an alpha-motor neuron membrane is much briefer than the refractory period in a skeletal muscle cell membrane.
(
Question 7) Which of the following statements about the absolute refractory period of cardiac muscle cells is TRUE?
A. It lasts for the same length of time in cardiac muscle cells as it does in skeletal muscle cells.
B. It is much longer than the refractory period of skeletal muscle cells.
C. It allows for tetanic contractions of the heart to occur to assure smooth, coordinated ejection of blood from the ventricles.
D. Ventricular muscle cells are in the absolute refractory period from the beginning of contraction until the beginning of their next contraction.
E. During the absolute refractory period, a larger-than-normal stimulus will result in a premature ventricular contraction.
(
Question 8) . Which of the following statements about membrane potentials in different types of cardiac cells is TRUE?
A. Myocardial cells have a resting membrane potential of about -90 mV; pacemaker cells do not have a true resting membrane potential.
B. Once threshold depolarization is reached in both myocardial and pacemaker cells, the rapid upswing of the action potential is caused by the opening of voltage-gated Na+ channels
C. Voltage-gated transient (T-type) Ca2+ channels are present in all of the different types of cells of the heart.
D. There are no L-type Ca2+ channels in cardiac muscle cells.
E. The upstroke of the action potential is steeper in SA node cells than it is in Purkinje cells.
(
Question 9) The QRS complex in an electrocardiogram best represents:
A. depolarization of the atria
B. repolarization of the atria
C. depolarization of the ventricles
D. repolarization of the ventricles
E. the delay at the AV node
(
Question 10) Which of the following would be most likely to be determined with a patient's ECG recording?
A. a heart murmur
B. stroke volume
C. cardiac output
D. blockage of conduction of electrical signals between the atria and the ventricles
E. a leaky atrioventricular valve
Quick Reply
