The Ventricles Are Complete Depolarized During Which Isoelectric Portion Of

Directions: Each of the numbered items or incomplete statements in this section is followed by answers or by completions of the statement. Select the ONE lettered answer or completion that is BEST in each case.

1. Arteriography of a patient's left renal artery shows narrowing of the radius of the artery by 50%. What is the expected change in blood flow through the stenotic artery?

(A) Decrease to V2

(C) Decrease to Vg

(D) Decrease to V16

2. When a person moves from a supine position to a standing position, which of the following compensatory changes occurs?

(A) Decreased heart rate

(B) Increased contractility

(C) Decreased total peripheral resistance (TPR)

(D) Decreased cardiac output

(E) Increased PR intervals

3. At which site is blood pressure the highest?

(B) Central vein

(C) Pulmonary artery

(D) Right atrium

(E) Renal artery

(F) Renal vein

4. A person's electrocardiogram (ECG) has no P wave, but has a normal QRS complex and a normal T wave. Therefore, his pacemaker is located in the

(A) sinoatrial (SA) node

(B) atrioventricular (AV) node

(C) bundle of His

(D) Purkinje system

(E) ventricular muscle

5. If the ejection fraction increases, there will be a decrease in

(A) cardiac output

(B) end-diastolic volume

(C) end-systolic volume

(D) heart rate

(E) pulse pressure

(F) stroke volume

(G) systolic pressure

Questions 6 and 7

An electrocardiogram (ECG) on a person shows ventricular extrasystoles.

6. The extrasystolic beat would produce

(A) increased pulse pressure because contractility is increased

(B) increased pulse pressure because heart rate is increased

(C) decreased pulse pressure because ventricular filling time is increased

(D) decreased pulse pressure because stroke volume is decreased

(E) decreased pulse pressure because the PR interval is increased

7. The next "normal" ventricular contraction that occurs after the extrasystole would produce

(A) increased pulse pressure because the contractility of the ventricle is increased

(B) increased pulse pressure because total peripheral resistance (TPR) is decreased

(C) increased pulse pressure because compliance of the veins is decreased

(D) decreased pulse pressure because the contractility of the ventricle is increased

(E) a decreased pulse pressure because TPR is decreased

8. An increase in contractility is demonstrated on a Frank-Starling diagram by

(A)

increased cardiac output for

a

given

end-

diastolic volume

(B)

increased cardiac output for

a

given

end-

systolic volume

(C)

decreased cardiac output for

a

given

end-

diastolic volume

(D)

decreased cardiac output for

a

given

end-

systolic volume systolic volume

Questions 9-12

Left ventricular volume (ml)

9. On the graph showing left ventricular volume and pressure, isovolumetric contraction occurs from point

10. The aortic valve closes at point

11. The first heart sound corresponds to point

12. If the heart rate is 70 beats/min, then the cardiac output of this ventricle is closest to

Questions 13 and 14

In a capillary, P<: is 30 millimeters of mercury (mm Hg), Pj is -2 mm Hg, ttc is 25 mm Hg, and it, is 2 mm Hg.

13. What is the direction of fluid movement and the net driving force?

(E) There is no net fluid movement

14. If Kf is 0.5 ml/min/mm Hg, what is the rate of water flow across the capillary wall?

15. The tendency for blood flow to be turbulent is increased by

(A) increased viscosity

(B) increased hematocrit

(C) partial occlusion of a blood vessel

(D) decreased velocity of blood flow

16. A patient experiences orthostatic hypotension after a sympathectomy. The explanation for this occurrence is

(A) an exaggerated response of the renin-angiotensin-aldosterone system

(B) a suppressed response of the renin-angiotensin-aldosterone system

(C) an exaggerated response of the baroreceptor mechanism

(D) a suppressed response of the baroreceptor mechanism

17. The ventricles are completely depolarized during which isoelectric portion of the electrocardiogram (ECG)?

(A) PR interval

(B) QRS complex

(C) QT interval

(D) ST segment

18. In which of the following situations is pulmonary blood flow greater than aortic blood flow?

(A) Normal adult

(C) Left-to-right ventricular shunt

(D) Right-to-left ventricular shunt

(E) Right ventricular failure

(F) Administration of a positive inotropic agent

19. The change indicated by the dashed lines on

19. The change indicated by the dashed lines on

Right atrial pressure (mm Hg) or end-diastolic volume (L)

Right atrial pressure (mm Hg) or end-diastolic volume (L)

(A) decreased cardiac output in the "new" steady state

(B) decreased venous return in the "new" steady state

(C) increased mean systemic pressure

(D) decreased blood volume

(E) increased myocardial contractility

20. A person's electrocardiogram (ECG) shows two P waves preceding each QRS complex. The interpretation of this pattern is

(A) decreased firing rate of the pacemaker in the sinoatrial (SA) node

(B) decreased firing rate of the pacemaker in the atrioventricular (AV) node

(C) increased firing rate of the pacemaker in the SA node

(D) decreased conduction through the AV node

(E) increased conduction through the His-Pur-kinje system

21. An acute decrease in arterial blood pressure elicits which of the following compensatory changes?

(A) Decreased firing rate of the carotid sinus nerve

(B) Increased parasympathetic outflow to the heart

(C) Decreased heart rate

(D) Decreased contractility

(E) Decreased mean systemic pressure

22. The tendency for edema to occur will be increased by

(A) arteriolar constriction

(B) increased venous pressure

(C) increased plasma protein concentration

(D) muscular activity

23. "Splitting" of the second heart sound occurs because

(A) the aortic valve closes before the pulmonic valve

(B) the pulmonic valve closes before the aortic valve

(C) the mitral valve closes before the tricuspid valve

(D) the tricuspid valve closes before the mitral valve

(E) filling of the ventricles has fast and slow components

24. During exercise, total peripheral resistance

(TPR) decreases because of the effect of

(A) the sympathetic nervous system on splanchnic arterioles

(B) the parasympathetic nervous system on skeletal muscle arterioles

(C) local metabolites on skeletal muscle arterioles

(D) local metabolites on cerebral arterioles

(E) histamine on skeletal muscle arterioles

Questions 25 and 26

Questions 25 and 26

25. Curve A in the figure represents

(A) aortic pressure

(B) ventricular pressure

(C) atrial pressure

(D) ventricular volume

26. Curve B in the figure represents

(A) left atrial pressure

(B) ventricular pressure

(C) atrial pressure

(D) ventricular volume

27. An increase in arteriolar resistance, without a change in any other component of the cardiovascular system, will produce

(A) a decrease in total peripheral resistance (TPR)

(B) an increase in capillary filtration

(C) an increase in arterial pressure

(D) a decrease in afterload

28. The following measurements were obtained in a male patient:

Heart rate: 70 beats/min Pulmonary vein [02] = 0.24 ml 02/ml Pulmonary artery [02] = 0.16 ml 02/ml Whole body 02 consumption: 500 ml/min

What is this patient's cardiac output?

29. Which of the following is the result of an inward Na+ current?

(A) Upstroke of the action potential in the sinoatrial (SA) node

(B) Upstroke of the action potential in Pur-kinje fibers

(C) Plateau of the action potential in ventricular muscle

(D) Repolarization of the action potential in ventricular muscle

(E) Repolarization of the action potential in the SA node

Questions 30 and 31

30. The dashed line in the figure illustrates the effect of

(A) increased total peripheral resistance (TPR)

(B) increased blood volume

(C) increased contractility

(D) a negative inotropic agent

(E) increased mean systemic pressure

31. The x-axis in the figure could have been labeled

(A) end-systolic volume

(B) end-diastolic volume

(C) pulse pressure

(D) mean systemic pressure

(E) heart rate

32. The greatest pressure decrease in the circulation occurs across the arterioles because

(A) they have the greatest surface area

(B) they have the greatest cross-sectional area

(C) the velocity of blood flow through them is the highest

(D) the velocity of blood flow through them is the lowest

(E) they have the greatest resistance

33. Pulse pressure is

(A) the highest pressure measured in the arteries

(B) the lowest pressure measured in the arteries

(C) measured only during diastole

(D) determined by stroke volume

(E) decreased when the capacitance of the arteries decreases

(F) the difference between mean arterial pressure and central venous pressure

34. In the sinoatrial (SA) node, phase 4 depolarization (pacemaker potential) is attributable to

(A) an increase in K+ conductance

(B) an increase in Na+ conductance

(C) a decrease in CI" conductance

(D) a decrease in Ca2+ conductance

(E) simultaneous increases in K+ and CI conductances

35. Propranolol has which of the following effects?

(A) Decreases heart rate

(B) Increases left ventricular ejection fraction

(C) Increases stroke volume

(D) Decreases splanchnic vascular resistance

(E) Decreases cutaneous vascular resistance

36. The low-resistance pathways between myocardial cells that allow for the spread of action potentials are the

(A) gap junctions

(C) sarcoplasmic reticulum (SR)

(D) intercalated disks

(E) mitochondria

37. Myocardial contractility is best correlated with the intracellular concentration of

38. Which of the following is an effect of histamine?

(A) Decreased capillary filtration

(B) Vasodilation of the arterioles

(C) Vasodilation of the veins

(D) Decreased Pc

(E) Interaction with the muscarinic receptors on the blood vessels

39. Carbon dioxide (C02) regulates blood flow to which one of the following organs?

(D) Skeletal muscle at rest

(E) Skeletal muscle during exercise

40. Cardiac output of the right side of the heart is what percentage of the cardiac output of the left side of the heart?

41. The physiologic function of the relatively slow conduction through the atrioventricular (AV) node is to allow sufficient time for

(A) runoff of blood from the aorta to the arteries

(B) venous return to the atria

(C) filling of the ventricles

(D) contraction of the ventricles

(E) repolarization of the ventricles

42. Blood flow to which organ is controlled primarily by the sympathetic nervous system rather than by local metabolites?

(D) Skeletal muscle during exercise

43. Which of the following parameters is decreased during moderate exercise?

(A) Arteriovenous 02 difference

(B) Heart rate

(C) Cardiac output

(D) Pulse pressure

(E) Total peripheral resistance (TPR)

44. Which of the following agents or changes has a negative inotropic effect on the heart?

(A) Increased heart rate

(B) Sympathetic stimulation

(C) Norepinephrine

(D) Acetylcholine (ACh)

(E) Cardiac glycosides

45. Which agent is released or secreted after a hemorrhage and causes an increase in renal Na+ reabsorption?

(A) Aldosterone

(B) Angiotensin I

(C) Angiotensin II

(D) Antidiuretic hormone (ADH)

(E) Atrial natriuretic peptide

46. Which of the following changes will cause an increase in myocardial 02 consumption?

(A) Decreased aortic pressure

(B) Decreased heart rate

(C) Decreased contractility

(D) Increased size of the heart

(E) Increased influx of Na+ during the upstroke of the action potential

47. Which of the following substances crosses capillary walls primarily through water-filled clefts between the endothelial cells?

(D) Glucose

Directions: Each set of matching questions in this section consists of a list of four to twenty-six lettered options (some of which may be in figures) followed by several numbered items. For each numbered item, select the ONE lettered option that is most closely associated with it. To avoid spending too much time on matching sets with large numbers of options, it is generally advisable to begin each set by reading the list of options. Then, for each item in the set, try to generate the correct answer and locate it in the option list, rather than evaluating each option individually. Each lettered option may be selected once, more than once, or not at all.

Questions 48-50

Questions 48-50

100 msec

Match each numbered phenomenon with the appropriate phase of the ventricular action potential shown in the figure.

48. Phase of the ventricular action potential in which the membrane potential is closest to the K* equilibrium potential

49. Phase of the ventricular action potential that has the highest conductance to Ca2+

50. Phase of the ventricular action potential that coincides with diastole

Questions 51 and 52

(A) a Receptors

(B) Pi Receptors

(C) p2 Receptors

(D) Muscarinic receptors

Match each function with the appropriate receptor.

51. Mediate constriction of arteriolar smooth muscle

52. Mediate slowing of the heart Questions 53-55

(A) Atrial systole

(B) Isovolumetric ventricular contraction

(C) Rapid ventricular ejection

(D) Reduced ventricular ejection

(E) Isovolumetric ventricular relaxation

(F) Rapid ventricular filling

(G) Reduced ventricular filling (diastasis)

Match each occurrence with the appropriate phase of the cardiac cycle.

53. Aortic pressure is highest

54. Ventricular volume is lowest

55. The mitral valve opens

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Responses

  • lemlem
    What compensatory changes occur when a person moves from a supine position to a standing position?
    2 years ago

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