Circulation MCQs



Circulation MCQs

14 November 2006

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 ½

b. Decrease to ¼

c. Decrease to 1/8

d. Decrease to 1/16

e. No change

2. Which of the following is the result of an inward sodium current?

a. Upstroke of the action potential in the SA node

b. Upstroke of the action potential in Purkinje fibres

c. Plateau of the action potential in ventricular muscle

d. Repolarisation of the action potential in ventricular muscle

e. Repolarisation of the action potential in the SA node

3. Which of the following has the highest blood flow? (ml/100g/min)?

a. Liver

b. Heart muscle

c. Kidneys

d. Skeletal muscle

e. Brain

4. The following factors serve to decrease heart rate EXCEPT

a. ( activity of baroreceptors in the arteries

b. expiration

c. ( ICP

d. ( blockers

e. Fear

5. Which of the following has a conduction rate of 0.05m/sec?

a. Ventricular muscle

b. Bundle of His

c. Atrial pathways

d. AV node

e. Purkinje system

6. The following changes may be seen on an ECG in a patient with serum K+ levels >8.5mmol/ℓ EXCEPT

a. P waves

b. Slurred QRS complex

c. Tall peaked T waves

d. QRS complex = 0.2 sec

e. Irregular rhythm

7. Regarding the cardiac cycle

a. Peak LV pressure is about 180mmHg

b. ED ventricular volume = 130ml

c. Isovolumetric ventricular contraction lasts about 0.5 seconds

d. 70% of ventricular filling occurs via atrial contraction

e. The amount of blood ejected by each ventricle/stroke at rest = 50ml

8. All of the following are vasoconstrictors EXCEPT

a. Endothelin

b. Bradykinin

c. Vasopressin

d. Angiotensin

e. Noradrenaline

9. Regarding BP control

a. ( baroreceptor discharge causes an increase in BP and an increase in cardiac output

b. Carotid receptors do not respond to pulse pressure changes

c. Afferents from aortic arch and carotid sinus areas extend to the vasomotor centre in the mid brain

d. Aortic arch receptors afferent nerve fibres form a distinct part of the glossopharyngeal nerve

e. Type A atrial stretch receptors discharge primarily during atrial systole

10. Which of the following has the greatest total cross sectional area

a. Small arteries

b. Venules

c. Arterioles

d. Small veins

e. Aorta

11. When a person rises from supine to standing, which of the following statements is correct

a. Stroke volume ( by 40%

b. TPR ( by 10%

c. Cardiac output ( by 15%

d. 1000ml blood pools centrally

e. Small vein pressure ( by 20mmHg

12. Regarding the jugular venous pulse

a. A “V” wave mirrors the rise in atrial pressure before the tricuspid valve closes

b. “A” wave is due to atrial diastole

c. Venous pressure increases during inspiration

d. “C” wave occurs during isovolumetric ventricular contraction

e. Giant “V” waves may indicate incomplete heart block

13. The Frank Starling mechanism means

a. The greater the heart muscle is stretched during filling, the greater will be the force of contraction

b. Within reasonable limits – changes in the arterial pressure against which the heart pumps have almost no effect on the cardiac output

c. Contribution of right atrial stretch to increasing amount of blood pumped each minute is much less than the Frank Starling mechanism

d. Within physiological limits – the heart pumps all the blood that comes to it without allowing excessive damming of blood in the veins

e. All of the above are true

14. Regulation of cerebral circulation is very important. Which of the following is correct

a. Cushing reflex serves to lower BP and increase HR in response to increased ICP

b. Autoregulation maintains a normal cerebral blood flow at arterial pressures of 65-140mmHg

c. O2 consumption of the brain is approximately 10% of the total body resting O2 consumption

d. A rise in venous pressure increases cerebral blood flow

e. Brainstem is more sensitive to hypoxia than the cerebral cortex

15. Regarding changes in cardiovascular function during isotonic exercise

a. Diastolic pressure rises markedly

b. Stroke volume changes relatively little

c. The amount of blood mobilised from the splanchnic area and other reservoirs may increase the amount of blood in the arterial portion of the circulation by as much as 60%

d. The AV O2 difference may increase upward of 10x volume % in exercise

e. Cardiac output may increase to values >55ℓ/minute

16. If under resting conditions, the heart rate is 70 beats/min, the cardiac output is 5.6ℓ/min, and the EDV is 160ml – what is the ejection fraction?

a. 0.40

b. 0.45

c. 0.50

d. 0.55

e. 0.60

17. Turbulence in a blood vessel is inversely proportional to

a. Viscosity of fluid

b. Velocity of flow

c. Diameter of the vessel

d. Density of fluid inside the vessel

e. The Reynolds number

18. The blood supply to the brain is

a. 250ml/min

b. 462ml/min

c. 750ml/min

d. 1260ml/min

e. 1500ml/min

19. Regarding the cardiac cycle

a. Phase 1 represents atrial systole

b. The aortic valve opens at the beginning of phase 2

c. The T wave of the ECG occurs during phase 4

d. The second heart sound is due to mitral valve closure

e. The C wave is due to the tricuspid valve opening

20. Concerning CSF

a. H+ ions cross the BBB into CSF with ease

b. Approximately 1550ml of CSF is produced/day

c. Osmolality is less than that of plasma because of its lower protein content

d. CSF pressure is normally 70-180mm CSF

e. Formation of CSF increases when the CSF pressure drops

21. The descending limb of Starling’s curve in the heart is due to

a. A decrease in the formation of cross bridges between actin and myosin

b. cAMP stimulation in the myocardial cells

c. The beginning of the disruption of myocardial fibres

d. Sodium and potassium ATPase inhibition

e. Phosphorylation of voltage dependent calcium channels by protein kinase A

22. In the cardiac cycle

a. RV systole precedes left

b. Peak RV pressure is around 25mmHg

c. The second heart sound is associated with mitral valve closure

d. The third heart sound represents turbulent flow in ventricular systole

e. Cardiac output drops with heart rates above 150/min

23. Regarding cardiac output

a. Increased cardiac contractile strength is a chronotropic effect

b. Cardiac index is about 1.6 litres

c. Eating increases CO by 100%

d. Increased EDV causes no change in CO

e. Can be measured by the direct Fick and indicator methods

24. Regarding control of BP

a. Baroreceptors are always found on the arterial side of the circulation

b. Afferents to the vasomotor centre include chemoreceptors in the carotid sinus

c. Deflation of the lungs results in a ( BP

d. Buffer nerves discharge at a low rate at normal BP levels

e. Carotid baroreceptors are located in the media of the carotid sinus

25. A decrease in stroke work is most likely to be caused by increasing

a. Contractility

b. Ejection fraction

c. Preload

d. Aortic compliance

e. Central venous pressure

26. If the QRS complex is positive in lead II and negative in lead III, the mean electrical axis is between

a. -30 and +30

b. +30 and +60

c. +60 and +90

d. +90 and +120

e. +120 and +150

27. Which of the following would cause the effect depicted by the dotted line on this graph?

[pic]

a. Cardiac depression 2( to hypoxia

b. Catecholamine response

c. Acetylcholine response

d. Congestive heart failure

e. MI

28. Cardiovascular changes that occur during inspiration include decreased

a. RV filling

b. RV output

c. LV contractility

d. Pressure gradient from extrathoracic veins to the right atrium

e. Systemic arterial pressure

For each condition listed – select the lettered point on the Frank Starling curves shown below with which it is most likely to be associated. (Assume point c is the resting state).

[pic]

29. Acute volume overload

30. Metabolic acidosis

31. Pericardial effusion

32. Muscular exercise

33. Which of the following characteristics is most similar in the systemic and pulmonary circulation?

a. Stroke work

b. Preload

c. Afterload

d. Peak systolic pressure

e. Blood volume

34. Cerebral blood flow is influenced by all of the following EXCEPT

a. Viscosity of the blood

b. pO2 of the arterial blood

c. CSF pressure

d. pH of the interstitial fluid of the brain

e. Vasomotor reflexes

35. The Hb oxygen saturation of blood entering the right ventricle is approximately

a. 95%

b. 85%

c. 75%

d. 55%

e. 35%

36. Neural control of circulation predominates over local control in which of the following organs

a. Skin

b. Brain

c. Heart

d. Skeletal muscle

e. Kidney

The tracing below represents normal jugular venous pulse. Which of the lettered responses corresponds with each statement?

A

B D

E

C

37. Reflects atrial systole

38. Increases in patients with tricuspid insufficiency

39. Citrate is a useful anticoagulant because of its ability to

a. Buffer basic groups of coagulation factors

b. Bind factor 12

c. Bind vitamin K

d. Chelate calcium

e. Be slowly metabolised

40. Venous pressure in the dural sinuses normally falls within which of the following ranges

a. Subatmospheric

b. 0-5mmHg

c. 5-10mmHg

d. 10-20mmHg

e. >20mmHg

Circulation MCQs 13 June 2006

Answers

1. D

2. B

3. C

4. A

5. D

6. A

7. B

8. B

9. E

10. B

11. A

12. D

13. E

14. B

15. D

16. C

17. A

18. C

19. A

20. D

21. C

22. B

23. E

24. D

25. D

26. A

27. B

28. E

29. D

30. E

31. B

32. A

33. B

34. E

35. C

36. A

37. A

38. B

39. D

40. A

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