3: The heart


 


1. What is her cardiac output in milliliters per minute?

A) 2000


B) 3000


C) 4000


D) 6000


E) 7000

2. When does the second heart sound occur in the ventricular pressure–volume relationship?

A) At point D


B) Between point A and point B


C) Between point B and point C


D) Between point C and point D


E) Between point D and point A

3. When does the third heart sound occur in the ventricular pressure–volume relationship?

A) At point D


B) Between point A and point B


C) Between point B and point C


D) Between point C and point D


E) Between point D and point A

4. What is her ventricular ejection fraction?

A) 33%


B) 50%


C) 60%


D) 67%


E) 80%

5. In which phase of the ventricular muscle action potential is the potassium permeability the highest?

A) 0


B) 1


C) 2


D) 3


E) 4

6. In a resting adult, the typical ventricular ejection fraction has what value?

A) 20%


B) 30%


C) 40%


D) 60%


E) 80%

7. A 30-year-old man has an ejection fraction of 0.25 and an end systolic volume of 150 ml. What is his end diastolic volume?

A) 50 ml


B) 100 ml


C) 125 ml


D) 200 ml


E) 250 ml

8. Which of the following statements about cardiac muscle is most accurate?

A) The T-tubules of cardiac muscle can store much less calcium than T-tubules in skeletal muscle


B) The strength and contraction of cardiac muscle depends on the amount of calcium surrounding cardiac myocytes


C) In cardiac muscle the initiation of the action potential causes an immediate opening of slow calcium channels


D) Cardiac muscle repolarization is caused by opening of sodium channels


E) Mucopolysaccharides inside the T-tubules bind chloride ions

9. A 60-year-old man’s EKG shows that he has an R-R interval of 0.55 sec. Which of the following best explains his condition?

A) He has fever


B) He has a normal heart rate


C) He has excess parasympathetic stimulation of the S-A node


D) He is a trained athlete at rest


E) He has hyperpolarization of the S-A node

10. Which of the following is most likely to cause the heart to go into spastic contraction?

A) Increased body temperature


B) Increased sympathetic activity


C) Decreased extracellular fluid potassium ions


D) Excess extracellular fluid potassium ions


E) Excess extracellular fluid calcium ions

11. Which of the following events occurs at the end of the period of ventricular ejection?

A) A-V valves close


B) Aortic valve opens


C) Aortic valve remains open


D) A-V valves open


E) Pulmonary valve closes

12. Which of the following phases of the cardiac cycle follows immediately after the beginning of the QRS wave?

A) Isovolumic relaxation


B) Ventricular ejection


C) Atrial systole


D) Diastasis


E) Isovolumic contraction

13. Which of the following conditions will result in a dilated, flaccid heart?

A) Excess calcium ions in the blood


B) Excess potassium ions in the blood


C) Excess sodium ions in the blood


D) Increased sympathetic stimulation


E) Increased norepinephrine concentration in the blood

14. A 25-year-old, well-conditioned athlete weighs 80 kg (176 lb). During maximal sympathetic stimulation, what is the plateau level of his cardiac output function curve?

A) 3 L/min


B) 5 L/min


C) 10 L/min


D) 13 L/min


E) 25 L/min

15. Which of the following events is associated with the first heart sound?

A) Closing of the aortic valve


B) Inrushing of blood into the ventricles during diastole


C) Beginning of diastole


D) Opening of the A-V valves


E) Closing of the A-V valves

16. Which of the following conditions at the A-V node will cause a decrease in heart rate?

A) Increased sodium permeability


B) Decreased acetylcholine levels


C) Increased norepinephrine levels


D) Increased potassium permeability


E) Increased calcium permeability

17. Sympathetic stimulation of the heart

A) Releases acetylcholine at the sympathetic endings


B) Decreases sinus nodal discharge rate


C) Decreases excitability of the heart


D) Releases norepinephrine at the sympathetic endings


E) Decreases cardiac contractility

18. What is the normal total delay of the cardiac impulse in the A-V node plus bundle?

A) 0.22 sec


B) 0.18 sec


C) 0.16 sec


D) 0.13 sec


E) 0.09 sec

19. Which of the following best explains how sympathetic stimulation affects the heart?

A) Permeability of the S-A node to sodium decreases


B) Permeability of the A-V node to sodium decreases


C) Permeability of the S-A node to potassium increases


D) There is an increased rate of upward drift of the resting membrane potential of the S-A node


E) Permeability of the cardiac muscle to calcium decreases

20. Which of the following structures will have the slowest rate of conduction of the cardiac action potential?

A) Atrial muscle


B) Anterior internodal pathway


C) A-V bundle fibers


D) Purkinje fibers


E) Ventricular muscle

21. If the S-A node discharges at 0.00 seconds, when will the action potential normally arrive at the epicardial surface at the base of the left ventricle?

A) 0.22 sec


B) 0.18 sec


C) 0.16 sec


D) 0.12 sec


E) 0.09 sec

22. If the S-A node discharges at 0.00 seconds, when will the action potential normally arrive at the A-V bundle (bundle of His)?

A) 0.22 sec


B) 0.18 sec


C) 0.16 sec


D) 0.12 sec


E) 0.09 sec

23. Which of the following conditions at the S-A node will cause heart rate to decrease?

A) Increased norepinephrine levels


B) Increased sodium permeability


C) Increased calcium permeability


D) Increased potassium permeability


E) Decreased acetylcholine levels

24. Which of the following are caused by acetylcholine?

A) Hyperpolarization of the S-A node


B) Depolarization of the A-V node


C) Decreased permeability of the S-A node to potassium ions


D) Increased heart rate


E) Increased permeability of the cardiac muscle to calcium ions

25. What is the membrane potential (threshold level) at which the S-A node discharges?

A) −40 mV


B) −55 mV


C) −65 mV


D) −85 mV


E) −105 mV

26. Which of the following conditions at the A-V node will cause a decrease in heart rate?

A) Increased sodium permeability


B) Decreased acetylcholine levels


C) Increased norepinephrine levels


D) Increased potassium permeability


E) Increased calcium permeability

27. If the ventricular Purkinje fibers become the pacemaker of the heart, what is the expected heart rate?

A) 30/min


B) 50/min


C) 65/min


D) 75/min


E) 85/min

28. What is the normal total delay of the cardiac impulse in the A-V node and the A-V bundle system?

A) 0.03 sec


B) 0.06 sec


C) 0.09 sec


D) 0.13 sec


E) 0.17 sec

29. What is the resting membrane potential of the sinus nodal fibers?

A) −100 mV


B) −90 mV


C) −80 mV


D) −55 mV


E) −20 mV

30. If the Purkinje fibers, situated distal to the A-V junction, become the pacemaker of the heart, what is the expected heart rate?

A) 30/min


B) 50/min


C) 60/min


D) 70/min


E) 80/min

31. Sympathetic stimulation of the heart normally causes which of the following conditions?

A) Acetylcholine release at the sympathetic endings


B) Decreased heart rate


C) Decreased rate of conduction of the cardiac impulse


D) Decreased force of contraction of the atria


E) Increased force of contraction of the ventricles

32. When recording lead I on an EKG, the right arm is the negative electrode, and the positive electrode is the

A) left arm


B) left leg


C) right leg


D) left arm + left leg


E) right arm + left leg

33. When recording lead aVL on an EKG, the positive electrode is the

A) left arm


B) left leg


C) right leg


D) left arm + left leg


E) right arm + left leg

34. A 70-year-old man was had the following EKG during his annual physical exam. What is his Q-T interval?

A) 0.12 sec


B) 0.16 sec


C) 0.22 sec


D) 0.30 sec


E) 0.40 sec

35. What is the heart rate in the following EKG?
image

 


A) 64


B) 70


C) 88


D) 94


E) 104

36. What is the normal QT interval?

A) 0.03 seconds


B) 0.13 seconds


C) 0.16 seconds


D) 0.20 seconds


E) 0.35 seconds

37. When recording lead II on an EKG, the positive electrode is the

A) left arm


B) left leg


C) right leg


D) left arm + left leg


E) right arm + left leg

38. When recording lead III on an EKG, the negative electrode is the

A) left arm


B) left leg


C) right leg


D) left arm + left leg


E) right arm + left leg

39. A 65-year-old man had an EKG recorded at a local emergency room following a biking accident. His weight was 80 kg and his aortic blood pressure was 160/90 mm Hg. The QRS voltage was 0.5 mV in lead I and 1.5 mV in lead III. What is the QRS voltage in lead II?

A) 0.5 mV


B) 1.0 mV


C) 1.5 mV


D) 2.0 mV


E) 2.5 mV

40. A ventricular depolarization wave when traveling −90° in the frontal plane will cause a large negative deflection in which lead?

A) aVR


B) aVL


C) Lead II


D) Lead III


E) aVF



Questions 41-43


A 60-year-old woman had the following EKG recorded at a local emergency room following an automobile accident. Her weight was 70 kg and her aortic blood pressure was 140/80 mm Hg.


image

 


41. What is the mean electrical axis calculated from standard leads I, II, and III shown in her EKG?

A) −90°


B) −50°


C) −12°


D) +100°


E) +170°

42. What is the heart rate using lead I for the calculation?

A) 70


B) 88


C) 100


D) 112


E) 148

43. What is her likely diagnosis?

A) Mitral valve stenosis


B) Left bundle branch block


C) Pulmonary valve stenosis


D) Right bundle branch block


E) Left ventricular hypertrophy

44. Which of the following conditions will usually result in right axis deviation in an EKG?

A) Systemic hypertension


B) Aortic valve stenosis


C) Aortic valve regurgitation


D) Excess abdominal fat

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Mar 25, 2017 | Posted by in PHYSIOLOGY | Comments Off on 3: The heart

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