End Lecture review questions Flashcards
Which one of the following would most likely occur as a direct result of applying a Ca++ channel blocker to a ventricular myocyte?
A. no effect
B. An increase in contractility
C. an increase in HR
D. a reduction in the duration of phase 2 of the action potential
E. Loss in phase 1 of the action potential
D. a reduction in the duration of phase 2 of the action potential
In contracting calcium muscle, calcium…
A. is present in an amount that usually saturates all intracellular calcium binding sites
B. comes from both the extracellular space and from the SR
C. enters the cell during the rapid upstroke (phase 0) of the AP
D. all of the above
E. none of the above
B. comes from both the extracellular space and from the SR
The Frank-Starling Relationship…
A. Explains the effect of ACh on ventricular performance
B. Explains the relationship between afterload (wall stress) and maximum +dP/dt
C. Is determined during isovolumic contraction
D. Explains the influence of positive inotropic agents on cardiac function
E. None of the above
E. None of the above
The opening of the mitral valve occurs at the beginning of which phase of the cardiac cycle? A. rapid ejection B. atrial systole C. isovolumic relaxation D. rapid filling E. isovolumic contraction
D. rapid filling
Using the figure, which of the following best describes AB in the ventricular pressure-volume loop?
A. isovolumic relaxation B. rapid ejection C. rapid filling D. isovolumic contraction E. SV
D. isovolumic contraction
Using the figure, what is the ejection fraction?
EF = SV/EDV
EF = (100-40)/100 = 60%
For any given preload and level of autonomic nerve activity, an increase in afterload tends to INCREASE:
A. Stroke volume
B. The velocity of myocardial shortening
C. Myocardial contractility
D. The rate of ejection of the stroke volume
E. Metabolic activity of cardiac myocytes
E. Metabolic activity of cardiac myocytes (heart has to work harder)
In response to a decrease in mean arterial blood pressure, the baroreceptor reflex mediates which of the following effects?
A. a decline in ventricular contractility
B. tachycardia and increased LV SV
C. bradycardia and increased LV afterload
D. increase in the firing rate of cranial nerve X innervating the heart
E. an increase in the firing in cranial nerve IX
B. tachycardia and increased LV SV
Upon assuming an upright posture, after lying quietly for several hours, the compensatory respond of the baroreceptor control system regulating arterial blood pressure will involve which of the following?
A. decreased sympathetic postganglionic nerve activity
B. decreased venoconstriction
C. increased firing in the carotid sinus nerve
D. increased heart rate
C. decreased CO
D. increased heart rate
Carotid sinus massage is sometimes used to stop supra ventricular tachycardia (rapid rhythms which originate above the ventricles). Which of the following is most likely explanation for the effectiveness of this maneuver?
A. It increases sympathetic discharge to the SA node
B. It decreases vagal discharge to the SA node
C. It increases vagal discharge to the conducting tissue between the atria and the ventricles
D. It increases the refractory period of the ventricular myocardium
E. It reduces the conduction velocity around the reentry loop
C. It increases vagal discharge to the conducting tissue between the atria and the ventricles
Mitral valve stenosis would be associated with:
A. low aortic diastolic pressure and a diastolic murmur
B. elevated left ventricular pressure and a systolic murmur
C. elevated left atrial pressure and a systolic murmur
D. elevated left atrial pressure and a diastolic murmur
E. elevated aortic pressure and no murmur
D. elevated left atrial pressure and a diastolic murmur
The sinoatrial (SA) node is the pacemaker for the heart because:
A. is the most richly innervated structure in the heart
B. is the only structure in the heart capable of generating action potentials
C. has the shortest absolute refractory period of all myocardial cells
D. has the highest rate of automatic discharge
E. is the cardiac cell that is least sensitive to catecholamines
D. has the highest rate of automatic discharge
An increased afterload (i.e., increased aortic pressure) on the ventricle would be expected to have which of the following effects on the heart?
A. Increase heart rate
B. Decrease preload reserve
C. Decrease left ventricular end-systolic volume
D. Decrease left ventricular end-diastolic volume
E. All of the above
B. Decrease preload reserve
Which of the following is/are CORRECT concerning the effect of catecholamines on myocardial cells?
A. they promote the phosphorylation of phospholamban, thereby enhancing the rate of relaxation of the myocardial cell
B. they inhibit the sarcolemmal Na+-K+ pump resulting in a reduced Na+-Ca++ exchange and an increased cytosolic Ca++ concentration
C. they reduce the influx of extracellular Ca++ via voltage- dependent Ca++ channels in the sarcolemma
D. they inhibit Ca++ reuptake into the sarcoplasmic reticulum resulting in an elevated cytosolic Ca++
E. Two of the above
F. None of the above
A. they promote the phosphorylation of phospholamban, thereby enhancing the rate of relaxation of the myocardial cell
D. they inhibit Ca++ reuptake into the sarcoplasmic reticulum resulting in an elevated cytosolic Ca++
E. Two of the above
Which of the following statements regarding the autonomic nervous system is CORRECT:
A. Parasympathetic activity increases the membrane permeability to K+
B. Sympathetic innervation decreases the slope of the
pacemaker potential
C. Sympathetic innervation decreases the membrane
permeability to Na+ and Ca++
D. The heart will stop beating if it is denervated
E. The heart rate will decrease significantly if the heart is denervated
A. Parasympathetic activity increases the membrane permeability to K+
