Chapter 9
Cardiac Physiology
TEST QUESTIONS
Multiple Choice systemic system as does the right ventricle into the
low-resistance, low-pressure pulmonary system.
1. The systemic circulation: (d) right ventricle must create higher tension
(a) receives more blood than the pulmonary within its walls.
circulation does. (e) left ventricle must pump oxygenated blood,
(b) receives blood from the left ventricle. which requires more energy than pumping
(c) is a high pressure system compared to the unoxygenated blood.
pulmonary circulation.
(d) receives blood from the left ventricle and is a ANSWER: c
high pressure system compared to the pulmonary
circulation. 5. Adjacent cardiac muscle cells are joined together
(e) all of these answers. end-to-end in the ventricles by:
(a) intercalated discs.
ANSWER: d (b) sarcomeres.
(c) Purkinje fibers.
2. Which valve(s) prevent regurgitation of blood (d) sinoatrial nodes.
from a right ventricle to atrium? (e) atrioventricular nodes.
(a) tricuspid.
(b) mitral. ANSWER: a
(c) bicuspid.
(d) both (a) and (b) above. 6. The primary function of the pericardial sac is to:
(e) all of these answers. (a) prevent excessive expansion of the heart as it
fills with blood.
ANSWER: a (b) secrete a fluid that reduces friction as the heart
beats.
3. Semilunar valves: (c) serve as a reservoir for blood to be used during
(a) prevent backflow of blood from the ventricles strenuous exercise.
to the atria. (d) provide oxygen and nutrients to the heart
(b) prevent backflow of blood from the atria to the muscle.
ventricles. (e) catch and kill any bacteria in the blood flowing
(c) prevent backflow of blood from the ventricles through the heart chambers.
to the arterial trunks.
(d) prevent backflow of blood from the arterial ANSWER: b
trunks to the ventricles.
(e) none of these answers. 7. The chordae tendineae:
(a) keep the AV valves from closing during
ANSWER: d ventricular contraction.
(b) hold the AV valves open during diastole.
4. The wall of the left ventricle is thicker than the (c) hold the right and left ventricles together.
wall of the right ventricle because the: (d) transmit the electrical impulse from the atria to
(a) left ventricle must pump much more blood the ventricles.
than the right ventricle so it must have stronger (e) contract when the ventricles contract.
walls.
(b) right ventricle must pump much more blood ANSWER: a
than the left ventricle so it has a larger chamber to
accommodate the blood and a correspondingly 8. The heart chamber having the greatest work load
thinner wall. is the:
(c) left ventricle must pump the same amount of (a) right ventricle.
blood into the high-resistance, high-pressure (b) left ventricle.
Cardiac Physiology 231
, (c) left atrium. (e) both (b) and (c) above.
(d) right atrium.
(e) both atria. ANSWER: b
ANSWER: b 14. Indicate which is the proper sequence of blood
flow through the circulatory system.
9. Select the vessel that carries blood with a 1. right atrium 6. pulmonary vein
comparatively high concentration of oxygen. 2. left atrium 7. lungs
(a) chordae tendineae. 3. right ventricle 8. systemic tissues
(b) inferior vena cava. 4. left ventricle 9. aorta
(c) pulmonary artery. 5. pulmonary artery 10. venae cavae
(d) pulmonary vein.
(e) superior vena cava. (a) 1—2—3—4—5—6—7—8—9—10
(b) 10—2—4—5—7—6—1—3—9—8
ANSWER: d (c) 10—1—3—5—7—6—2—4—9—8
(d) 10—1—2—3—4—5—7—6—9—8
10. The aortic valve: (e) 10—1—3—5—9—7—6—2—4—9
(a) prevents the backflow of blood into the aorta
during ventricular diastole. ANSWER: c
(b) prevents the backflow of blood into the left
ventricle during ventricular diastole. 15. The low-resistance pathway that permits electrical
(c) prevents the backflow of blood into the right activity pass from cell-to-cell in myocardial tissue
ventricle during ventricular diastole. is the:
(d) closes when the first heart sound is heard. (a) desmosome.
(e) none of these answers. (b) septum.
(c) gap junction.
ANSWER: b (d) T-tubule.
(e) sarcoplasmic reticulum.
11. The right half of the heart pumps blood through
the _______ circuit and the left half pumps blood ANSWER: c
through the _______ circuit.
(a) systolic, diastolic. 16. What component of the cardiac conduction system
(b) coronary, pulmonary. distributes electrical signals through the papillary
(c) systemic, pulmonary. muscles directly?
(d) pulmonary, systemic. (a) AV nodes.
(e) systemic, coronary. (b) AV bundle.
(c) bundle of His.
ANSWER: d (d) Purkinjie fibers.
(e) SA node.
12. Regarding fetal circulation, which statement is
incorrect? ANSWER d
(a) The foramen ovale interconnects the atria.
(b) The ligamentum arteriosum shunts blood from 17. The plateau of the cardiac action potential results
the pulmonary artery directly into the aorta. from the opening of voltage-gated slow ______
(c) The fetus has two lung bypasses. channels in the plasma membrane of the cardiac
(d) The umbilical vein carries oxygen-rich blood cell.
to the fetus. (a) sodium
(e) All of these answers. (b) potassium
(c) calcium
ANSWER: b (d) chloride
(e) glucose
13. Blood returning from the lungs:
(a) enters the right atrium. ANSWER: c
(b) enters the left atrium.
(c) is poorly oxygenated. 18. Which of the following statements concerning
(d) both (a) and (b) above. action potentials in the heart is correct?
232 Chapter Nine
, (a) The rising phase of the action potential in 22. Select the incorrect statement about cardiac
cardiac autorhythmic cells is due to a rapid Ca2+ muscle cells.
influx. (a) All of them contract in the heart or none of
(b) The rising phase of the action potential in them contract.
cardiac contractile cells is due to a rapid Na+ (b) They are capable of graded strength of
influx. contraction.
(c) The plateau phase of the action potential in (c) They are produced constantly after infancy.
cardiac contractile cells is due to a slow Ca2+ (d) They have an abundance of mitochondria.
influx. (e) They have an abundance of myoglobin.
(d) Two of these answers.
(e) All of these answers. ANSWER: c
ANSWER: e 23. The normal pacemaker of the heart is the:
(a) SA node.
19. On a normal ECG, a wave for repolarization of the (b) AV node.
atria is not recorded. Why? (c) bundle of His.
(a) The leads are not placed in a position to pick it (d) Purkinje system.
up. (e) ventricular myocardium.
(b) No repolarization of the atria occurs normally.
(c) It occurs simultaneously with ventricular ANSWER: a
depolarization and is masked by the QRS
complex. 24. The function of the atrioventricular node is to
(d) It does not travel through body fluids. (a) excite the left and right atrium.
(e) It is too small to be picked up by external (b) control the heart rate.
recording electrodes. (c) prevent the atria and ventricles from
contracting simultaneously.
ANSWER: c (d) repolarize the heart after systole.
(e) none of these answers.
20. Which of the following criteria must be met for
the heart to function efficiently? ANSWER: c
(a) Excitation and consequently contraction of the
cardiac muscle fibers of each heart chamber 25. The direction of the impulse through the
should be coordinated to ensure efficient pumping. conduction system of the heart for each cardiac
(b) The atria should be excited and contract before cycle is normally:
the onset of ventricular contraction to ensure that (a) AV node—SA node—bundle of His—Purkinje
ventricular filling is complete. fibers
(c) The right side of the heart should contract first (b) AV node—bundle of His—SA node—Purkinje
to ensure that oxygenated blood is delivered to the fibers
heart before the left side contracts. (c) bundle of His—AV node—Purkinje fibers—
(d) Two of these answers. SA node
(e) All of these answers. (d) SA node—AV node—bundle of His—Purkinje
fibers
ANSWER: d (e) SA node—bundle of His—Purkinje fibers—
AV node
21. The AV nodal delay:
(a) ensures that the atria contract and empty their ANSWER: d
contents into the ventricles prior to ventricular
systole. 26. The QRS complex represents:
(b) ensures that the ventricles contract prior to (a) depolarization of the atria.
atrial systole. (b) depolarization of the ventricles.
(c) ensures that tetanic contraction of cardiac (c) the AV nodal delay.
muscle is impossible. (d) repolarization of the ventricles.
(d) is shortened by parasympathetic stimulation. (e) the time during which the heart is contracting.
(e) more than one of the above.
ANSWER: b
ANSWER: a
Cardiac Physiology 233
Cardiac Physiology
TEST QUESTIONS
Multiple Choice systemic system as does the right ventricle into the
low-resistance, low-pressure pulmonary system.
1. The systemic circulation: (d) right ventricle must create higher tension
(a) receives more blood than the pulmonary within its walls.
circulation does. (e) left ventricle must pump oxygenated blood,
(b) receives blood from the left ventricle. which requires more energy than pumping
(c) is a high pressure system compared to the unoxygenated blood.
pulmonary circulation.
(d) receives blood from the left ventricle and is a ANSWER: c
high pressure system compared to the pulmonary
circulation. 5. Adjacent cardiac muscle cells are joined together
(e) all of these answers. end-to-end in the ventricles by:
(a) intercalated discs.
ANSWER: d (b) sarcomeres.
(c) Purkinje fibers.
2. Which valve(s) prevent regurgitation of blood (d) sinoatrial nodes.
from a right ventricle to atrium? (e) atrioventricular nodes.
(a) tricuspid.
(b) mitral. ANSWER: a
(c) bicuspid.
(d) both (a) and (b) above. 6. The primary function of the pericardial sac is to:
(e) all of these answers. (a) prevent excessive expansion of the heart as it
fills with blood.
ANSWER: a (b) secrete a fluid that reduces friction as the heart
beats.
3. Semilunar valves: (c) serve as a reservoir for blood to be used during
(a) prevent backflow of blood from the ventricles strenuous exercise.
to the atria. (d) provide oxygen and nutrients to the heart
(b) prevent backflow of blood from the atria to the muscle.
ventricles. (e) catch and kill any bacteria in the blood flowing
(c) prevent backflow of blood from the ventricles through the heart chambers.
to the arterial trunks.
(d) prevent backflow of blood from the arterial ANSWER: b
trunks to the ventricles.
(e) none of these answers. 7. The chordae tendineae:
(a) keep the AV valves from closing during
ANSWER: d ventricular contraction.
(b) hold the AV valves open during diastole.
4. The wall of the left ventricle is thicker than the (c) hold the right and left ventricles together.
wall of the right ventricle because the: (d) transmit the electrical impulse from the atria to
(a) left ventricle must pump much more blood the ventricles.
than the right ventricle so it must have stronger (e) contract when the ventricles contract.
walls.
(b) right ventricle must pump much more blood ANSWER: a
than the left ventricle so it has a larger chamber to
accommodate the blood and a correspondingly 8. The heart chamber having the greatest work load
thinner wall. is the:
(c) left ventricle must pump the same amount of (a) right ventricle.
blood into the high-resistance, high-pressure (b) left ventricle.
Cardiac Physiology 231
, (c) left atrium. (e) both (b) and (c) above.
(d) right atrium.
(e) both atria. ANSWER: b
ANSWER: b 14. Indicate which is the proper sequence of blood
flow through the circulatory system.
9. Select the vessel that carries blood with a 1. right atrium 6. pulmonary vein
comparatively high concentration of oxygen. 2. left atrium 7. lungs
(a) chordae tendineae. 3. right ventricle 8. systemic tissues
(b) inferior vena cava. 4. left ventricle 9. aorta
(c) pulmonary artery. 5. pulmonary artery 10. venae cavae
(d) pulmonary vein.
(e) superior vena cava. (a) 1—2—3—4—5—6—7—8—9—10
(b) 10—2—4—5—7—6—1—3—9—8
ANSWER: d (c) 10—1—3—5—7—6—2—4—9—8
(d) 10—1—2—3—4—5—7—6—9—8
10. The aortic valve: (e) 10—1—3—5—9—7—6—2—4—9
(a) prevents the backflow of blood into the aorta
during ventricular diastole. ANSWER: c
(b) prevents the backflow of blood into the left
ventricle during ventricular diastole. 15. The low-resistance pathway that permits electrical
(c) prevents the backflow of blood into the right activity pass from cell-to-cell in myocardial tissue
ventricle during ventricular diastole. is the:
(d) closes when the first heart sound is heard. (a) desmosome.
(e) none of these answers. (b) septum.
(c) gap junction.
ANSWER: b (d) T-tubule.
(e) sarcoplasmic reticulum.
11. The right half of the heart pumps blood through
the _______ circuit and the left half pumps blood ANSWER: c
through the _______ circuit.
(a) systolic, diastolic. 16. What component of the cardiac conduction system
(b) coronary, pulmonary. distributes electrical signals through the papillary
(c) systemic, pulmonary. muscles directly?
(d) pulmonary, systemic. (a) AV nodes.
(e) systemic, coronary. (b) AV bundle.
(c) bundle of His.
ANSWER: d (d) Purkinjie fibers.
(e) SA node.
12. Regarding fetal circulation, which statement is
incorrect? ANSWER d
(a) The foramen ovale interconnects the atria.
(b) The ligamentum arteriosum shunts blood from 17. The plateau of the cardiac action potential results
the pulmonary artery directly into the aorta. from the opening of voltage-gated slow ______
(c) The fetus has two lung bypasses. channels in the plasma membrane of the cardiac
(d) The umbilical vein carries oxygen-rich blood cell.
to the fetus. (a) sodium
(e) All of these answers. (b) potassium
(c) calcium
ANSWER: b (d) chloride
(e) glucose
13. Blood returning from the lungs:
(a) enters the right atrium. ANSWER: c
(b) enters the left atrium.
(c) is poorly oxygenated. 18. Which of the following statements concerning
(d) both (a) and (b) above. action potentials in the heart is correct?
232 Chapter Nine
, (a) The rising phase of the action potential in 22. Select the incorrect statement about cardiac
cardiac autorhythmic cells is due to a rapid Ca2+ muscle cells.
influx. (a) All of them contract in the heart or none of
(b) The rising phase of the action potential in them contract.
cardiac contractile cells is due to a rapid Na+ (b) They are capable of graded strength of
influx. contraction.
(c) The plateau phase of the action potential in (c) They are produced constantly after infancy.
cardiac contractile cells is due to a slow Ca2+ (d) They have an abundance of mitochondria.
influx. (e) They have an abundance of myoglobin.
(d) Two of these answers.
(e) All of these answers. ANSWER: c
ANSWER: e 23. The normal pacemaker of the heart is the:
(a) SA node.
19. On a normal ECG, a wave for repolarization of the (b) AV node.
atria is not recorded. Why? (c) bundle of His.
(a) The leads are not placed in a position to pick it (d) Purkinje system.
up. (e) ventricular myocardium.
(b) No repolarization of the atria occurs normally.
(c) It occurs simultaneously with ventricular ANSWER: a
depolarization and is masked by the QRS
complex. 24. The function of the atrioventricular node is to
(d) It does not travel through body fluids. (a) excite the left and right atrium.
(e) It is too small to be picked up by external (b) control the heart rate.
recording electrodes. (c) prevent the atria and ventricles from
contracting simultaneously.
ANSWER: c (d) repolarize the heart after systole.
(e) none of these answers.
20. Which of the following criteria must be met for
the heart to function efficiently? ANSWER: c
(a) Excitation and consequently contraction of the
cardiac muscle fibers of each heart chamber 25. The direction of the impulse through the
should be coordinated to ensure efficient pumping. conduction system of the heart for each cardiac
(b) The atria should be excited and contract before cycle is normally:
the onset of ventricular contraction to ensure that (a) AV node—SA node—bundle of His—Purkinje
ventricular filling is complete. fibers
(c) The right side of the heart should contract first (b) AV node—bundle of His—SA node—Purkinje
to ensure that oxygenated blood is delivered to the fibers
heart before the left side contracts. (c) bundle of His—AV node—Purkinje fibers—
(d) Two of these answers. SA node
(e) All of these answers. (d) SA node—AV node—bundle of His—Purkinje
fibers
ANSWER: d (e) SA node—bundle of His—Purkinje fibers—
AV node
21. The AV nodal delay:
(a) ensures that the atria contract and empty their ANSWER: d
contents into the ventricles prior to ventricular
systole. 26. The QRS complex represents:
(b) ensures that the ventricles contract prior to (a) depolarization of the atria.
atrial systole. (b) depolarization of the ventricles.
(c) ensures that tetanic contraction of cardiac (c) the AV nodal delay.
muscle is impossible. (d) repolarization of the ventricles.
(d) is shortened by parasympathetic stimulation. (e) the time during which the heart is contracting.
(e) more than one of the above.
ANSWER: b
ANSWER: a
Cardiac Physiology 233
