The Cardiovascular System: The Heart

1. 18 The Cardiovascular System: The Heart

2. The principle of complementary structure and function is evident when examining the coverings of the heart. In what way is this relationship evident? • The pericardium surrounds the heart. • The epicardium and visceral layer of the pericardium are synonymous. • The pericardial cavity surrounds the heart. • The visceral and parietal membranes of the pericardium are smooth and slide past each other, providing a low-friction environment for heart movement.

3. Of the following layers of the heart wall, which consumes the most energy? • Epicardium • Myocardium • Endocardium • Visceral pericardium

4. Which of the following structures is an exception to the general principle surrounding blood vessel oxygenation levels? • Pulmonary artery • Aorta • Pulmonary veins • Both a and c

5. What purpose does the coronary circuit serve? • None; it is a vestigial set of vessels. • It delivers 1/20 of the body’s blood supply to the heart muscle itself. • It delivers blood to the anterior lung surface for gas exchange. • It feeds the anterior thoracic wall.

6. A heart murmur would be detected when blood is heard flowing from the ________ to the __________ through the ___________. • right atrium; right ventricle; tricuspid valve • right atrium; left atrium; tricuspid valve • left ventricle; left atrium; mitral valve • left atrium; left ventricle; mitral valve

7. The presence of intercalated discs between adjacent cardiac muscle cells causes the heart to behave as a _____________. • single chamber • contractile myofibril • desmosome • functional syncytium

8. Cardiac muscle cells have several similarities with skeletal muscle cells. Which of the following is not a similarity? • The cells are each innervated by a nerve ending. • The cells store calcium ions in the sarcoplasmic reticulum. • The cells contain sarcomeres. • The cells become depolarized when sodium ions enter the cytoplasm.

9. The plateau portion of the action potential in contractile cardiac muscle cells is due to: • an increased potassium permeability. • an influx of calcium ions. • an influx of sodium ions. • exit of calcium ions from the sarcoplasmic reticulum.

10. The stimulus for the heart’s rhythmic contractions comes from _________. • intercalated discs • acetylcholine • a neuromuscular junction • a pacemaker potential

11. The major ionic change that initiates the rising phase of the autorhythmic cell action potential is __________. • potassium ion exit • sodium ion entry • calcium ion entry • calcium ion exit

12. For which type of heart condition might a doctor prescribe calcium channel blockers? • Depressed heart rate • Heart irritability • Heart murmur • Weak heart rate

13. In a normal heart, which of the following structures is responsible for setting the heart’s pace? • Sinoatrial node • Atrioventricular node • Atrioventricular bundle • Purkinje fibers

14. Predict the nature of an ECG recording when the atrioventricular node becomes the pacemaker. • There would continue to be a normal sinus rhythm. • The P wave would be much larger than normal. • The rhythm would be slower. • The T wave would be much smaller than normal.

15. The primary input to the heart by the cardioinhibitory center is primarily found in the ___________. • sinoatrial node and atrioventricular node • Purkinje fibers • the cardiac contractile fibers • bundle of His

16. The “lub-dup” heart sounds are produced by: • the walls of the atria and ventricles slapping together during a contraction. • the blood hitting the walls of the ventricles and arteries, respectively. • the closing of the atrioventricular valves (“lub”) and the closing of the semilunar valves (“dup”). • the closing of the semilunar valves (“lub”) and the closing of the atrioventricular valves (“dup”).

17. Atrial systole occurs _______ the firing of the sinoatrial node. • before • after • simultaneously with • alternately with

18. The majority (80%) of ventricular filling occurs ___________. • during late ventricular systole • passively through blood flow alone • with atrial systole • both a and b

19. In terms of blood flow, why is it important that atrial diastole occurs just as ventricular systole begins? • Blood is continually propelled in a forward motion down its pressure gradient. • The atria need that time to prepare for the next contraction. • Ventricular systole pulls the remaining 20% of blood volume from the atria. • Blood would flow too fast otherwise.

20. Cardiac output is determined by________. • heart rate • stroke volume • cardiac reserve • both a and b

21. Predict what would happen to the end systolic volume (ESV) if contraction force were to increase. • It would decrease. • It would increase. • It would remain constant. • ESV is not affected by contraction force.

22. The Frank-Starling law of the heart can be demonstrated when an individual takes a deep breath. This is because: • the heart expands during inhalation. • the negative intrathoracic pressure induces a larger than normal venous return to the right atrium, thereby stretching the wall of the right ventricle. • sympathetic impulses are sent to the heart during inspiration. • both a and c occur.

23. Your heart seems to “pound” after you hear a sudden, loud noise. This increased contractility is: • because you were startled. • because when a gasp of surprise is emitted, the Frank-Starling law of the heart is evident. • due to norepinephrine causing threshold to be reached more quickly. • because acetylcholine release is inhibited.

24. Predict what happens to end diastolic volume when an increase in heart rate is not accompanied by an increase in contractility. • End diastolic volume is increased. • End diastolic volume is decreased. • End diastolic volume is unchanged. • End diastolic volume is not affected by heart rate.

25. What is the nature of acetylcholine’s inhibitory effect on heart rate? • Acetylcholine induces depolarization in the sinoatrial node. • Acetylcholine causes closing of sodium channels in the sinoatrial node. • Acetylcholine causes opening of fast calcium channels in contractile cells. • Acetylcholine causes opening of potassium channels in the sinoatrial node, thereby hyperpolarizing it.

26. Why is high blood pressure damaging to the heart? • With high blood pressure, the blood is more viscous and harder to pump. • The heart rate slows down to dangerously low levels if blood pressure is too high. • Due to increased afterload, the left ventricle must contract more forcefully to expel the same amount of blood. • Sodium concentration increases during high blood pressure and is toxic to the myocardium.