help me solve these questions please 1. Which of these statements correctly desc
ID: 50066 • Letter: H
Question
help me solve these questions please
1. Which of these statements correctly describes the systemic circulation?
a. It receives more blood than the pulmonary circulation.
b. It receives blood from the right ventricle.
c. It is a low-pressure system compared to the pulmonary circulation.
d. It is a high-pressure system compared to the pulmonary circulation.
2. According to the text, why is the wall of the left ventricle thicker than the wall of the right ventricle?
a. The left ventricle must pump much more blood than the right ventricle, so it must have stronger walls.
b. The right ventricle must pump much more blood than the left ventricle, so it has a larger chamber to
accommodate the blood and a correspondingly thinner wall.
c. The left ventricle must pump the same amount of blood into the high-resistance,
high-pressure systemic system as does the right ventricle into the low-resistance,
low-pressure pulmonary system.
d. The right ventricle must create higher tension within its walls.
3. Which of the following actions is done by the chordae tendineae?
a. keep the AV valves from closing during ventricular contraction
b. hold the AV valves open during diastole
c. hold the right and left ventricles together
d. transmit the electrical impulse from the atria to the ventricles
4. The right half of the heart pumps blood through the pulmonary circuit. Through which circuit does the left half pump blood?
a. diastolic
b. pulmonary
c. systolic
d. systemic
5. Which of the following describes blood returning from the lungs?
a. It enters the right atrium.
b. It enters the left atrium.
c. It is poorly oxygenated.
d. It enters the left ventricle.
6. Which of these statements correctly describes action potentials in the heart?
a. The rising phase of the action potential in cardiac autorhythmic cells is due to a rapid Ca2+ influx.
b. The rising phase of the action potential in cardiac contractile cells is due to a rapid K+ influx.
c. The plateau phase of the action potential in cardiac contractile cells is due to a rapid Ca2+ influx.
d. The plateau phase of the action potential in cardiac contractile cells is due to a rapid K+ influx.
7. Which of these statements does NOT correctly describe cardiac muscle cells?
a. All of them contract in the heart or none of them contract.
b. They are capable of graded strength of contraction.
c. They are produced constantly after infancy.
d. They have an abundance of mitochondria.
8. What is the normal direction of the impulse through the conduction system of the heart for each cardiac cycle?
a. AV node, SA node, bundle of His, Purkinje fibres
b. AV node, bundle of His, SA node, Purkinje fibres
c. bundle of His, AV node, Purkinje fibres, SA node
d. SA node, AV node, bundle of His, Purkinje fibres
9. Which of these ECG waves represents ventricular repolarization?
a. P wave
b. QRS complex
c. T wave
d. Ventricular repolarization occurs simultaneously with atrial depolarization and consequently cannot be recorded.
10. Why is the sinoatrial node the heart’s normal pacemaker?
a. It has the fastest natural rate of autorhythmicity.
b. It has both sympathetic and parasympathetic innervation.
c. It is under the control of AV node.
d. Activation of K+ channels occurs more rapidly in this region than elsewhere in the heart.
11. The electrocardiogram is most useful in determining which component of cardiac output?
a. stroke volume
b. end-diastolic volume
c. ejection fraction
d. heart rate
12. What is the membrane potential of cardiac muscle cells at rest?
A –110 mV
B –90 mV
C –60 mV
D –50 mV
13. Which of the following factors will NOT increase cardiac output?
a. increased venous return
b. increased parasympathetic stimulation
c. increased preload
d. increased heart rate
14. Which is the result of vagal influences on the heart?
a. enhanced potassium permeability at the SA node
b. enhanced calcium permeability at the SA node
c. more frequent depolarization of the SA node
d. stimulation of the heart by epinephrine
15. Which of the following actions produces the second heart sound?
a. opening of the AV valves
b. closing of the AV valves
c. opening of the semilunar valves
d. closing of the semilunar valves
16. What happens during isovolumetric ventricular contraction?
a. The ventricles fill rapidly.
b. No blood enters or leaves the ventricles.
c. The maximum volume of blood is ejected.
d. The maximum rate of ejection occurs.
17. Which of these statements correctly describes cardiac output?
a. the volume of blood pumped by each ventricle during each contraction or beat
b. the volume of blood pumped by each ventricle per minute
c. stroke volume × SVR (systemic vascular resistance)
d. the volume of blood pumped by each atrium into ventricles
18. What rhythm characterizes atrial flutter as impulses pass from the AV node to the ventricles?
A 1:1
B 2:1
C 3:4
D 5:2
19. Twelve complete ECG patterns are recorded from a subject over 10 seconds. If this pattern continues, what is the rate of the heartbeat in the subject?
A 60 beats per minute
B 72 beats per minute
C 90 beats per minute
D 108 beats per minute
20. Which of the following statements correctly describes the Frank–Starling law of the heart?
a. The shorter the initial length of the cardiac muscle fibres prior to contraction, the more forceful will be the subsequent
contraction because the fibres are already partially contracted.
b. Increasing the venous return increases the end-diastolic volume, which leads to an increased stroke volume,
so the heart normally pumps out all the blood returned to it.
c. As cardiac output is reduced, blood pools in the vasculature so that arterial blood pressure increases.
d. The output of the left side of the heart must always exceed that of the right side of the heart because the right
side pumps blood only to the lungs, whereas the left side must pump blood to the rest of the body.
21. Which of the following is the cranial nerve of the parasympathetic nervous system that signals the heart?
a. cardiac
b. coronary
c. trigeminal
d. vagus
22. If the EDV were held constant, what could accomplish increased stroke volume?
a. increased sympathetic nerve activity to the heart
b. increased parasympathetic nerve activity to the heart
c. decreased contractility
d. increased arterial blood pressure
23. Which of these statements correctly applies to the cardiac muscle?
a. It extracts oxygen and nutrients from the blood within its chambers.
b. It receives its blood supply primarily during ventricular systole when blood is forced into the vessels
supplying the heart.
c. It receives its blood supply as the blood returning to the heart from the lung passes through the cardiac
circulation before being pumped to the systemic circulation.
d. It receives most of its blood supply during ventricular diastole by means of the coronary circulation.
24. The second heart sound occurs when the semilunar valves close. What does this mark?
a. the start of the ejection period
b. the start of systole
c. the end of the ejection period
d. the start of isovolumetric contraction
25. Which of the following is a compensatory mechanism that comes into play in order to maintain the
cardiac output for the failing heart?
a. decreased myocardial contractility
b. increased vagal stimulation
c. increased sympathetic stimulation
d. peripheral vasodilation
Explanation / Answer
1- c. It is a low-pressure system compared to the pulmonary circulation.
2- a. The left ventricle must pump much more blood than the right ventricle, so it must have stronger and thicker walls
3- a. keep the AV valves from closing during ventricular contraction
4- d. systemic
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