MCQ CVS

Question 1

1. Which of the following is NOT an inward current?
 A. I Na
 B. I Ca
 C. I f
 D. I Na-K (pump)

Answer 1

C

Question 2

7. Which of the following is a CORRECT order of blood flow through the heart?
 1 - right atrium
 2 - left atrium
 3 - right ventricle
 4 - left ventricle
 5 - vena cava
 6 - pulmonary artery
 7 - pulmonary vein
 8 - tricuspid AV valve
 9 - bicuspid (mitral) AV valve
 10 - pulmonary valve
 11 - aortic valve
 12 - aorta

A. 5, 1, 9, 3, 10, 6, 7, 2, 8, 4, 11, 12
B. 5, 1, 8, 3, 10, 7, 6, 2, 9, 4, 11, 12
C. 5, 1, 8, 3, 10, 6, 7, 2, 9, 4, 11, 12
D. 5, 1, 8, 3, 11, 6, 7, 2, 9, 4, 10, 12

Answer 2

c

Question 3

9. Which of the following is NOT a part of the specialized conduction system of the heart?
 A. Cells of the SA node.
 B. Cells of the AV node.
 C. Working myocardial cells.
 D. His bundle.
 E. Purkinje fibers.

Answer 3

C

Question 4

10. Which of the following is INCORRECT concerning cardiac muscle?
    A. Cardiac cells are smaller than skeletal muscle cells.
    B. Electrical communication between cardiac cells is maintained via gap junctions which are specialized portions of the intercalated discs.
    C. Mechanical attachment of cardiac cells is at the intercalated disc.
    D. The spread of excitation through the heart muscle is 3-dimensional.
    E. Transverse tubules are larger in skeletal muscle than in heart muscle allowing more diffusion of Ca2+ into the interior of the cell.

Answer 4

E

Question 5

11. Which of the following is usually the dominant pacemaker and fires the fastest?
 A. SA node.
 B. AV node
 C. His bundle.
 D. Purkinje fibers.

Answer 5

A

Question 6

Which of the following is NOT true of the parasympathetic control of the heart?
A. It affects muscarinic receptors.
B. It decreases heart rate via the SA node.
C. It decreases conduction velocity via the AV node.
D. It can be blocked by beta blockers, e.g. propranolol.

Answer 6

D

Question 7

Which of the following is a TRUE statement concerning pacemaker potential?
A. Specialized cells depolarize during phase 4, but ventricular and atrial muscle cells do not.
B. Specialized cells depolarize during phase 3, but ventricular and atrial muscle cells do not.
C. Specialized cells repolarize during phase 4, but ventricular and atrial muscle cells do not.
D. Specialized cells repolarize during phase 3, but ventricular and atrial muscle cells do not.
E. None are correct

Answer 7

A

Question 8

Which of the following is INCORRECT concerning the voltage clamp technique?
A. The voltage clamp technique is used to record action potentials from heart cells
B. It is useful to measure effects of antiarrhythmic agents on specific ion channels.
C. The voltage clamp can be used to set the Vm either for a segment of the cell membrane or the entire cell.
D. It allows the investigator to measure both the magnitude and time course of the ionic current generated by ions moving through channels.

Answer 8

A

Question 9

Which of the following is the property of a cardiac cell to initiate and fire an action potential on its own without external stimulation?
 A. Selectivity
 B. Spontaneity.
 C. Automaticity.
 D. Conductance.

Answer 9

C

Question 10

Which of the following does NOT show rapid initial depolarization at the start of an action potential?
 A. SA node.
 B. Atrial muscle.
 C. Purkinje fibers.
 D. Ventricular muscle.
 E. Bundle of His.

Answer 10

A

Question 11

Sodium enters the cell during the upstroke of the action potential. What is the major mechanism for removing Na from the cell?
A. It passively diffuses out of the cell.
B. It is extruded via an ATP-dependent Na-K pump.
C. It is extruded via an ATP-dependent Na-Ca pump.
D. It is extruded via an ATP-independent Na-K pump.
E. It is extruded via an ATP-independent Na-Ca pump.

Answer 11

b

Question 12

If sodium channels are open, membrane potential is +110 mV, and the equilibrium potential is +68 mV, how will sodium ions respond?
 A. They will move into the cell.
 B. They will move out of the cell.
 C. They will not move.
 D. The conductance will drop to zero.

Answer 12

B

Question 13

Which of the following is NOT true of an inward ionic current?
A. It is negative.
B. It reduces the polarity of the cell.
C. It makes the membrane potential more negative.
D. It can be caused by Na ions moving into the cell
E. It can be caused by anions moving out of the cell.

Answer 13

C

Question 14

If you reduced the outward current in a heart cell, what would be the result?
A. Increase the rate of repolarization.
B. Prolong the action potential.
C. Increase the rate of depolarization

Answer 14

B

Question 15

Which of the following is INCORRECT concerning diastolic depolarization at the SA node?
A. It results from a decrease in IK.
B. Results from the activation of If carried mainly by Na ions.
C. Its rate is decreased by sympathetic stimulation.
D. Activating IKACh decreases its rate.
E. Its rate is decreased by decreasing ICa

Answer 15

C

Question 16

If the heart rate increases, which of the following would be a result?
A. ERP would increase while APD would decrease.
B. ERP would decrease while APD would increase.
C. Both ERP and APD would increase.
D. Both ERP and APD would decrease.

Answer 16

D

Question 17

. Which of the following is INCORRECT concerning local circuit flow in the heart?
A. It flows from regions with high membrane potential to regions with low potential.
B. The cell with the more negative potential is called the current source, while the one with the more positive potential is called the current sink.
C. The circuit flows from the current source to the current sink.
D. The circuit flows from the active cell to the resting cells in its vicinity.

Answer 17

B

Question 18

Which of the following will increase the length constant involved in the local circuit current flow of the heart?
A. Increase in membrane resistance.
B. Increase in extracellular resistance.
C. Increase in intracellular resistance.
D. None of the above.

Answer 18

A

Question 19

Which of the following will decrease the Vmax and sodium current in a myocardial cell?
A. A premature heart beat.
B. Late membrane depolarization.
C. Low extracellular potassium levels.
D. More than normal activated Na channels.

Answer 19

A

Question 20

Which of the following is INCORRECT concerning gap junctions?
A. They are composed of junctional channels which have two connexons each.
B. Connexin protein subunits are arranged around a central pore to compose each connexon.
C. Gap junctions are more abundant in the atria and ventricles than they are in the SA and AV nodes.
D. Increases in cytosolic Ca and H will increase gap junction channel conductance.

Answer 20

D

Question 21

Which of the following is NOT true concerning the differences between skeletal and cardiac muscle?
A. The heart has a relatively large T-tubule volume.
B. The heart has a larger more developed sarcoplasmic reticulum.
C. The heart relies more on extracellular Ca stores than skeletal muscle.
D. With limited extracellular Ca, skeletal muscle can contract for close to an hour, while heart muscle can only contract for a few seconds.

Answer 21

B

Question 22

Which of the following is NOT a method of Ca removal following contraction of heart muscle?
A. Na-Ca exchange transports Ca out of the cell.
B. ATP-dependent sarcolemmal Ca pumps remove Ca from the cell.
C. Ca passively diffuses out of the cell.
D. ATP-dependent SR Ca pumps move Ca from the cytoplasm into the SR.

Answer 22

C

Question 23

Which of the following is FALSE concerning the regulation of heart muscle performance?
A. Recruiting more numbers of motor units will increase the strength of contraction.
B. Increases in end-diastolic volume will generate a larger stroke volume during systole.
C. The amount and duration of Ca released from the SR can alter contractility.
D. Positive inotropic agents will increase contractility.

Answer 23

A

Question 24

Which of the following pairs is INCORRECT?
A. P wave: atrial depolarization
B. QRS complex: ventricular depolarization
C. T wave: ventricular repolarization
D. QT interval: Measure of duration of atrial action potential

Answer 24

D

Question 25

``` Which of the following pairs in INCORRECT concerning the Einthoven triangle? A. Lead I: RA/LA B. Lead II: RA/LL C. Lead III: LA/LL D. All of the pairs are correct. ```

Answer 25

D

Question 26

``` Which of the following is NOT affected by the preload in the heart muscle? A. End systolic volume B. End diastolic volume C. Stroke Volume D. Ejection fraction. E. Cardiac output. ```

Answer 26

A

Question 27

Which of the following is INCORRECT concerning isotonic contraction in the heart? A. One occurs during the ejection phase of the cardiac cycle. B. Is typically the first step in heart muscle contraction followed by an isometric contraction. C. It involves a change in muscle length against a constant load. D. An increased afterload will slow the velocity of muscle shortening.

Answer 27

B

Question 28

Which of the following is NOT an effect of a positive inotropic agent on the heart? A. It increases stroke volume. B. It increases the initial velocity of muscle shortening at all loads. C. It increases the rate of blood ejection from the heart. D. It decreases the rate of rise in ventricular blood pressure during systole.

Answer 28

D

Question 29

Which of the following will require the smallest increase in oxygen consumption by the heart? A. Generating an increase in left ventricular pressure. B. Severe hypertension. C. Generating an increase in stroke volume. D. Aortic stenosis.

Answer 29

C

Question 30

``` Which of the following vessels has the largest effect on total peripheral resistance? A. Arteries. B. Arterioles. C. Veins. D. Venules. E. Capillaries. ```

Answer 30

B

Question 31

``` If you decrease a blood vessel's radius in half, by what fraction does the blood flow change? A. 1/2 B. 1/4 C. 1/8 D. 1/16 E. 1/32 ```

Answer 31

D

Question 32

Which of the following is INCORRECT concerning turbulent blood flow? A. The resistance to turbulent flow is greater than laminar flow. B. Above a critical velocity, blood flow becomes turbulent. C. Turbulence can create vibrations that can be detected as murmurs. D. Turbulence is found normally in the aorta and in narrowed vessels. E. Turbulent flow rate is proportional to the cube root of the driving pressure.

Answer 32

E

Question 33

``` . Which of the following blood vessels has the greatest compliance? A. Arteries. B. Veins. C. Arterioles. D. Capillaries. ```

Answer 33

B

Question 34

Which of the following pairs is INCORRECT? A. Nitric oxide (NO): vasodilator B. Endothelin: vasoconstrictor C. Nitric Oxide (NO): promotes cell growth D. Endothelin: potent positive inotropic effect

Answer 34

C

Question 35

``` Which of the following will NOT increase aortic systolic blood pressure? A. Decrease in arterial compliance B. Decrease in aortic distensibility. C. Increase in stroke volume. D. Decrease in ejection velocity. ```

Answer 35

D

Question 36

``` Which of the following is a correct formula for the mean arterial blood pressure? A. MAP = CO X SV B. MAP = CO X HR C. MAP = SV X HR X TPR D. MAP = HR X TPR ```

Answer 36

C

Question 37

Which of the following pairs is INCORRECT concerning arteriolar tone? A. Myogenic control: vascular smooth muscle responds to changes in pressure. B. Metabolic control: accumulation of waste products stimulates vasoconstriction. C. Neural control: vasoconstriction activated by sympathetic nerves. D. Hormonal control: catecholamines affect the adrenergic receptors of the vascular smooth muscle.

Answer 37

B

Question 38

Which pair is INCORRECT concerning the microcirculation at the capillary level? A. Tight junctions: brain B. Gaps large enough to exchange plasma proteins: kidneys C. Intercellular junctions / pores: exchange of water and lipid-insoluble substances. D. Pinocytosis: cytoplasmic vesicles exchanging fluid and solutes. E. Intracellular fenestrations: exchange of large molecules.

Answer 38

B

Question 39

If a patient is suffering from swollen hands, feet, and face, all of the following could be a cause, except? A. Large decrease in arterial blood pressure. B. Lymphatic blockage. C. A decrease in plasma proteins. D. Increase in capillary permeability to proteins. E. Vasodilation.

Answer 39

A

Question 40

``` Which of the following is NOT a mechanism to promote venous return and reduce blood pooling? A. One way venous valves. B. Parasympathetic stimulation. C. Skeletal muscle pump. D. Thoraco-abdominal pump E. Pumping of the heart. ```

Answer 40

B

Question 41

Which of the following in INCORRECT concerning a patient with ventricular tachycardia? A. It occurs when the heart rate drops to dangerously low levels. B. Cardiac output can falls to dangerous levels. C. Arterial blood pressure falls to dangerous levels. D. It involves impaired ventricular filling.

Answer 41

A

Question 42

Which of the following would NOT occur following a major blood loss? A. Vagal tone to the SA node would be decreased which would then increase the heart rate. B. An increase in sympathetic output in arterioles would increase the total peripheral resistance, except in the brain and heart. C. Sympathetic output to the atria and ventricles would increase resulting in an increase in stroke volume. D. Sympathetic output to the veins would increase, resulting in increased venous pressure, venous return, and cardiac output. E. Stroke volume would increase while heart rate decreased. Together this would increase the cardiac output.

Answer 42

E