Download 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.
b.
c.
d.
e.
2.
Liver
Heart muscle
Kidneys
Skeletal muscle
Brain
The following factors serve to decrease heart rate EXCEPT
a.
b.
c.
d.
e.
5.
Upstroke of the action potential in the SA node
Upstroke of the action potential in Purkinje fibres
Plateau of the action potential in ventricular muscle
Repolarisation of the action potential in ventricular muscle
Repolarisation of the action potential in the SA node
Which of the following has the highest blood flow? (ml/100g/min)?
a.
b.
c.
d.
e.
4.
½
¼
1/8
1/16
Which of the following is the result of an inward sodium current?
a.
b.
c.
d.
e.
3.
Decrease to
Decrease to
Decrease to
Decrease to
No change
 activity of baroreceptors in the arteries
expiration
 ICP
 blockers
Fear
Which of the following has a conduction rate of 0.05m/sec?
a.
b.
c.
d.
e.
Ventricular muscle
Bundle of His
Atrial pathways
AV node
Purkinje system
6.
The following changes may be seen on an ECG in a patient with serum K+
levels >8.5mmol/ℓ EXCEPT
a.
b.
c.
d.
e.
7.
Regarding the cardiac cycle
a.
b.
c.
d.
e.
8.
b.
c.
d.
e.
 baroreceptor discharge causes an increase in BP and an increase in
cardiac output
Carotid receptors do not respond to pulse pressure changes
Afferents from aortic arch and carotid sinus areas extend to the
vasomotor centre in the mid brain
Aortic arch receptors afferent nerve fibres form a distinct part of the
glossopharyngeal nerve
Type A atrial stretch receptors discharge primarily during atrial systole
Which of the following has the greatest total cross sectional area
a.
b.
c.
d.
e.
11.
Endothelin
Bradykinin
Vasopressin
Angiotensin
Noradrenaline
Regarding BP control
a.
10.
Peak LV pressure is about 180mmHg
ED ventricular volume = 130ml
Isovolumetric ventricular contraction lasts about 0.5 seconds
70% of ventricular filling occurs via atrial contraction
The amount of blood ejected by each ventricle/stroke at rest = 50ml
All of the following are vasoconstrictors EXCEPT
a.
b.
c.
d.
e.
9.
P waves
Slurred QRS complex
Tall peaked T waves
QRS complex = 0.2 sec
Irregular rhythm
Small arteries
Venules
Arterioles
Small veins
Aorta
When a person rises from supine to standing, which of the following
statements is correct
a.
b.
c.
d.
e.
Stroke volume  by 40%
TPR  by 10%
Cardiac output  by 15%
1000ml blood pools centrally
Small vein pressure  by 20mmHg
12.
Regarding the jugular venous pulse
a.
b.
c.
d.
e.
13.
The Frank Starling mechanism means
a.
b.
c.
d.
e.
14.
The greater the heart muscle is stretched during filling, the greater will
be the force of contraction
Within reasonable limits – changes in the arterial pressure against
which the heart pumps have almost no effect on the cardiac output
Contribution of right atrial stretch to increasing amount of blood
pumped each minute is much less than the Frank Starling mechanism
Within physiological limits – the heart pumps all the blood that comes
to it without allowing excessive damming of blood in the veins
All of the above are true
Regulation of cerebral circulation is very important. Which of the following is
correct
a.
b.
c.
d.
e.
15.
A “V” wave mirrors the rise in atrial pressure before the tricuspid valve
closes
“A” wave is due to atrial diastole
Venous pressure increases during inspiration
“C” wave occurs during isovolumetric ventricular contraction
Giant “V” waves may indicate incomplete heart block
Cushing reflex serves to lower BP and increase HR in response to
increased ICP
Autoregulation maintains a normal cerebral blood flow at arterial
pressures of 65-140mmHg
O2 consumption of the brain is approximately 10% of the total body
resting O2 consumption
A rise in venous pressure increases cerebral blood flow
Brainstem is more sensitive to hypoxia than the cerebral cortex
Regarding changes in cardiovascular function during isotonic exercise
a.
b.
c.
d.
e.
Diastolic pressure rises markedly
Stroke volume changes relatively little
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%
The AV O2 difference may increase upward of 10x volume % in
exercise
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.
b.
c.
d.
e.
17.
Turbulence in a blood vessel is inversely proportional to
a.
b.
c.
d.
e.
18.
Phase 1 represents atrial systole
The aortic valve opens at the beginning of phase 2
The T wave of the ECG occurs during phase 4
The second heart sound is due to mitral valve closure
The C wave is due to the tricuspid valve opening
Concerning CSF
a.
b.
c.
d.
e.
21.
250ml/min
462ml/min
750ml/min
1260ml/min
1500ml/min
Regarding the cardiac cycle
a.
b.
c.
d.
e.
20.
Viscosity of fluid
Velocity of flow
Diameter of the vessel
Density of fluid inside the vessel
The Reynolds number
The blood supply to the brain is
a.
b.
c.
d.
e.
19.
0.40
0.45
0.50
0.55
0.60
H+ ions cross the BBB into CSF with ease
Approximately 1550ml of CSF is produced/day
Osmolality is less than that of plasma because of its lower protein
content
CSF pressure is normally 70-180mm CSF
Formation of CSF increases when the CSF pressure drops
The descending limb of Starling’s curve in the heart is due to
a.
b.
c.
d.
e.
A decrease in the formation of cross bridges between actin and
myosin
cAMP stimulation in the myocardial cells
The beginning of the disruption of myocardial fibres
Sodium and potassium ATPase inhibition
Phosphorylation of voltage dependent calcium channels by protein
kinase A
22.
In the cardiac cycle
a.
b.
c.
d.
e.
23.
Regarding cardiac output
a.
b.
c.
d.
e.
24.
c.
d.
e.
Baroreceptors are always found on the arterial side of the circulation
Afferents to the vasomotor centre include chemoreceptors in the
carotid sinus
Deflation of the lungs results in a  BP
Buffer nerves discharge at a low rate at normal BP levels
Carotid baroreceptors are located in the media of the carotid sinus
A decrease in stroke work is most likely to be caused by increasing
a.
b.
c.
d.
e.
26.
Increased cardiac contractile strength is a chronotropic effect
Cardiac index is about 1.6 litres
Eating increases CO by 100%
Increased EDV causes no change in CO
Can be measured by the direct Fick and indicator methods
Regarding control of BP
a.
b.
25.
RV systole precedes left
Peak RV pressure is around 25mmHg
The second heart sound is associated with mitral valve closure
The third heart sound represents turbulent flow in ventricular systole
Cardiac output drops with heart rates above 150/min
Contractility
Ejection fraction
Preload
Aortic compliance
Central venous pressure
If the QRS complex is positive in lead II and negative in lead III, the mean
electrical axis is between
a.
b.
c.
d.
e.
-30 and +30
+30 and +60
+60 and +90
+90 and +120
+120 and +150
27.
Which of the following would cause the effect depicted by the dotted line on
this graph?
LV
Stroke
Work
LV end diastolic fibre length
a.
b.
c.
d.
e.
Cardiac depression 2 to hypoxia
Catecholamine response
Acetylcholine response
Congestive heart failure
MI
28.
Cardiovascular changes that occur during inspiration include decreased
a.
b.
c.
d.
e.
RV filling
RV output
LV contractility
Pressure gradient from extrathoracic veins to the right atrium
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).
Contractility
A
A
D
C
B
A
E
Ventricular EDV
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.
b.
c.
d.
e.
34.
Stroke work
Preload
Afterload
Peak systolic pressure
Blood volume
Cerebral blood flow is influenced by all of the following EXCEPT
a.
b.
c.
d.
e.
Viscosity of the blood
pO2 of the arterial blood
CSF pressure
pH of the interstitial fluid of the brain
Vasomotor reflexes
35.
The Hb oxygen saturation of blood entering the right ventricle is
approximately
a.
b.
c.
d.
e.
36.
95%
85%
75%
55%
35%
Neural control of circulation predominates over local control in which of the
following organs
a.
b.
c.
d.
e.
Skin
Brain
Heart
Skeletal muscle
Kidney
The tracing below represents normal jugular venous pulse. Which of the lettered
responses corresponds with each statement?
A
B
D
C
37.
Reflects atrial systole
38.
Increases in patients with tricuspid insufficiency
39.
Citrate is a useful anticoagulant because of its ability to
a.
b.
c.
d.
e.
40.
E
Buffer basic groups of coagulation factors
Bind factor 12
Bind vitamin K
Chelate calcium
Be slowly metabolised
Venous pressure in the dural sinuses normally falls within which of the
following ranges
a.
b.
c.
d.
e.
Subatmospheric
0-5mmHg
5-10mmHg
10-20mmHg
>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