Deck 9: Cardiac Physiology

Question 1

The heart chamber having the greatest work load is the

A) right ventricle.
B) left ventricle.
C) left atrium.
D) right atrium.
E) they each have the same workload.

Answer 1

left ventricle.

Question 2

Which valve is associated with the S2 heart sound?

A) tricuspid.
B) mitral.
C) bicuspid.
D) both (a) and (b) above.
E) none of these answers.

Answer 2

none of these answers.

Question 3

Indicate which is the proper sequence of blood flow through the circulatory system.

A) 1-2-3-4-5-6-7-8-9-10
B) 10-2-4-5-7-6-1-3-9-8
C) 10-1-3-5-7-6-2-4-9-8
D) 10-1-2-3-4-5-7-6-9-8
E) none of these answers.

Answer 3

10-1-3-5-7-6-2-4-9-8

Question 4

On a normal ECG, a wave for repolarization of the atria is not recorded. Why?

A) the leads are not placed in a position to pick it up.
B) no repolarization of the atria occurs normally.
C) it occurs simultaneously with ventricular depolarization and is masked by the QRS complex.
D) it does not travel through body fluids.
E) it is too small to be picked up by external recording electrodes.

Question 5

The low-resistance pathway that permits electrical activity pass from cell-to-cell in myocardial tissue is the

A) desmosome.
B) septum.
C) gap junction.
D) T-tubule.
E) sarcoplasmic reticulum.

Question 6

The wall of the left ventricle is thicker than the wall of the right ventricle because the

A) left ventricle must pump much more blood than the right ventricle so it must have stronger walls.
B) 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) 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) right ventricle must create higher tension within its walls.
E) left ventricle must pump oxygenated blood, which requires more energy than pumping unoxygenated blood.

Question 7

Semilunar valves

A) prevent backflow of blood from the ventricles to the atria.
B) prevent backflow of blood from the atria to the ventricles.
C) prevent backflow of blood from the ventricles to the arterial trunks.
D) prevent backflow of blood from the arterial trunks to the ventricles.
E) none of these answers.

Question 8

The systemic circulation

A) receives more blood than the pulmonary circulation does.
B) receives blood from the left ventricle.
C) is a high pressure system compared to the pulmonary circulation.
D) receives blood from the left ventricle and is a high pressure system compared to the pulmonary circulation.
E) all of these answers.

Question 9

Select the vessel carrying blood with a comparatively high concentration of oxygen.

A) aorta
B) inferior vena cava.
C) pulmonary artery.
D) pulmonary vein.
E) both (a) and (d)

Question 10

The AV nodal delay

A) ensures that the atria contract and empty their contents into the ventricles prior to ventricular systole.
B) ensures that the ventricles contract prior to atrial systole.
C) ensures that tetanic contraction of cardiac muscle is impossible.
D) is shortened by parasympathetic stimulation.
E) more than one of the above is correct.

Question 11

Which of the following statements concerning action potentials in the heart is correct?

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 Na⁺ influx.
C) The plateau phase of the action potential in cardiac contractile cells is due to a slow Ca²⁺ influx.
D) Two of these answers are correct.
E) All of these answers are correct.

Question 12

The heart chamber that received blood from the vena cava is the:

A) right ventricle.
B) left ventricle.
C) left atrium.
D) right atrium.
E) both (c) and (d)

Question 13

The plateau of the cardiac action potential results from the opening of voltage-gated slow ____ channels in the plasma membrane of the cardiac cell.

A) sodium
B) potassium
C) calcium
D) chloride
E) glucose

Question 14

Blood returning from the vena cava:

A) enters the right atrium.
B) enters the left atrium.
C) is poorly oxygenated.
D) both (a) and (c) above.
E) both (b) and (c) above.

Question 15

What component of the cardiac conduction system distributes electrical signals through the papillary muscles directly?

A) AV nodes.
B) AV bundle.
C) bundle of His.
D) Purkinje fibers.
E) SA node.

Question 16

Select the incorrect statement about 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.
E) they have an abundance of myoglobin.

Question 17

The aortic valve

A) prevents the backflow of blood into the aorta during ventricular diastole.
B) prevents the backflow of blood into the left ventricle during ventricular diastole.
C) prevents the backflow of blood into the right ventricle during ventricular diastole.
D) closes when the first heart sound is heard.
E) none of these answers.

Question 18

The right half of the heart pumps blood through the ____ circuit and the left half pumps blood through the ____ circuit.

A) systolic, diastolic.
B) coronary, pulmonary.
C) systemic, pulmonary.
D) pulmonary, systemic.
E) systemic, coronary.

Question 19

The chordae tendineae

A) keep the AV valves from prolapsing 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.
E) contract when the ventricles contract.

Question 20

Adjacent cardiac muscle cells are joined together end-to-end in the ventricles by

A) intercalated discs.
B) sarcomeres.
C) Purkinje fibers.
D) sinoatrial nodes.
E) atrioventricular nodes.

Question 21

The time period between the P wave and the QRS complex is lengthened. Which of the following is likely not functioning correctly?

A) SA node.
B) AV node.
C) bundle of His.
D) Purkinje system.
E) ventricular myocardium.

Question 22

The QRS complex represents

A) depolarization of the atria.
B) depolarization of the ventricles.
C) the AV nodal delay.
D) repolarization of the ventricles.
E) the time during which the heart is contracting.

Question 23

Sympathetic stimulation increases contractile strength by:

A) decreasing sodium permeability
B) increasing calcium permeability
C) closing funny channels
D) cause the resting potential to become more negative
E) increasing threshold

Question 24

Funny channels control which of the following currents?

A) inward sodium
B) outward sodium
C) inward potassium
D) outward potassium
E) inward calcium

Question 25

The AV node

A) is the normal pacemaker of the heart.
B) is the only electrical connection between the atria and the ventricles.
C) rapidly conducts the impulse from the atria to the ventricles so that they contract simultaneously.
D) is not innervated by the vagus.
E) has the fastest rate of depolarization in the heart.

Question 26

The membrane potential of cardiac muscle cells at rest is about ____ mV.

A) -110
B) -90
C) -70
D) -50
E) -30

Question 27

Which of the following characteristic is associated with funny channels?

A) the plateau phase of a cardiac action potential
B) they open after threshold is reached
C) they allow the influx of calcium
D) they open when the membrane potential becomes hyperpolarized
E) both (a) and (c)

Question 28

The fastest rate of autorhythmicity is normally carried out by the

A) AV bundle.
B) AV node.
C) bundle of His.
D) Purkinje fibers.
E) SA node.

Question 29

The direction of the impulse through the conduction system of the heart for each cardiac cycle is normally

A) AV node-SA node-bundle of His-Purkinje fibers.
B) AV node-bundle of His-SA node-Purkinje fibers.
C) bundle of His-AV node-Purkinje fibers-SA node.
D) SA node-AV node-bundle of His-Purkinje fibers.
E) SA node-bundle of His-Purkinje fibers-AV node.

Question 30

Electrical activity occurs at the AV node

A) during the P wave.
B) between the P wave and QRS complex.
C) during the QRS complex.
D) between the QRS complex and T wave.
E) during the T wave.

Question 31

The function of the ventricular conduction system of the heart is to

A) spread of the action potential throughout the large ventricular mass to ensure a single, coordinated contraction of the ventricles.
B) spread the action potential in the absence of sympathetic stimulation.
C) set the heart rate.
D) spread the action potential throughout the atria and ventricles.
E) slow down the original action potential so it has time to spread throughout the large ventricular mass.

Question 32

Which is the normal sequence of the spread of cardiac excitation?

A) 2-3-1-5-4-6
B) 3-2-1-4-5-6
C) 2-3-1-4-5-6
D) 1-2-3-4-5-6
E) none of these answers.

Question 33

The electrocardiogram is most useful in determining which component of cardiac output?

A) stroke volume
B) heart rate
C) ejection fraction
D) end-diastolic volume
E) murmurs

Question 34

The refractory period of cardiac muscle

A) lasts almost as long as the contraction period.
B) is much longer than the refractory period in skeletal muscle.
C) allows tetanic contraction of the heart to occur to ensure smooth, coordinated ejection of blood from the ventricles.
D) both (a) and (b) above.
E) all of these answers.

Question 35

The sinoatrial node is the heart's normal pacemaker because

A) it has the fastest natural rate of autorhythmicity.
B) it has both sympathetic and parasympathetic innervation.
C) it lies in the right atrium.
D) activation of K+ channels occurs more rapidly in this region than elsewhere in the heart.
E) none of these answers.

Question 36

Which of the following ECG waves represents atrial repolarization?

A) P wave.
B) QRS complex.
C) T wave.
D) atria don't repolarize
E) the wave does not appear on an ECG because it occurs at the same time as the QRS complex

Question 37

The normal pacemaker of the heart is the

A) SA node.
B) AV node.
C) bundle of His.
D) Purkinje system.
E) ventricular myocardium.

Question 38

Why can't tetany of the heart occur?

A) there are no distinct motor units in the heart.
B) there is inadequate oxygen supply via the coronary circulation to metabolically support a sustained contraction.
C) the refractory period in cardiac muscle lasts almost as long as the duration of the resultant contraction.
D) the heart contracts with maximal force every beat so it is impossible to increase the strength of cardiac contraction.
E) vagal stimulation slows down the heart rate to prevent summation of contractions.

Question 39

During the isovolumetric phase of ventricular systole:

A) the ventricles are contracting isometrically.
B) the atrioventricular valves and semilunar valves are closed.
C) blood is ejected into the great vessels.
D) the ventricles are relaxing.
E) both (a) and (b) above.

Question 40

Which of the following ECG waves represents ventricular repolarization?

A) P wave.
B) QRS complex.
C) T wave.
D) PR segment.
E) ventricular repolarization occurs simultaneously with atrial depolarization and consequently cannot be recorded.

Question 41

Which is true when you are sympathetically stimulated?

A) the SA node depolarizes more rapidly.
B) the myocardium repolarizes more rapidly.
C) more Ca²⁺ results in more sarcomere crossbridge attachments.
D) norepinephrine is stimulating the heart.
E) all of these answers.

Question 42

Funny channels:

A) control currents through cardiac muscle cells
B) are involved in producing pacemaker potentials
C) allow calcium to pass into the cell
D) both (b) and (c)
E) none of the above

Question 43

Cardiac output

A) is maintained at a relatively constant value at rest
B) is the volume of blood pumped by each ventricle per minute.
C) equals heart rate x (EDV-ESV)
D) increases with exercise
E) all of the above

Question 44

Although the heart does not require the nervous system to initiate contraction events:

A) it is sympathetically innervated via cardiac nerve fibers.
B) it is parasympathetically innervated by vagus nerve fibers.
C) it is innervated by the phrenic nerve.
D) it is innervated by the sympathetic division of the autonomic nervous system only.
E) both (a) and (b) above.

Question 45

Under resting conditions:

A) heart rate is dominated by sympathetic activity
B) heart rate is dominated by parasympathetic activity
C) acetylcholine suppresses NE release
D) both (a) and (c)
E) both (b) and (c)

Question 46

The aortic valve opens

A) when ventricular pressure exceeds aortic pressure.
B) at the start of systole.
C) at the maximum ventricular pressure.
D) immediately after atrial contraction.
E) none of these answers.

Question 47

Each of the following factors will increase cardiac output except:

A) increased venous return.
B) secretion of acetylcholine onto the SA node
C) increased EDV
D) increased heart rate.
E) increased force of ventricular contraction.

Question 48

The cardiac output is equal to

A) the difference between the end-diastolic volume (EDV) and the end-systolic volume (ESV) x HR.
B) the product of heart rate and EDV.
C) the difference between the stroke. volume at rest and the stroke volume during exercise.
D) the stroke volume less the end-systolic volume.
E) the product of heart rate and blood pressure.

Question 49

The first heart sound

A) occurs when the AV valves close.
B) occurs when the semilunar valves close.
C) signals the onset of ventricular systole.
D) occurs when the AV valves close and signals the onset of ventricular systole.
E) occurs when the semilunar valves close and signals the onset of ventricular systole.

Question 50

The second heart sound is produced by the

A) opening of the AV valves.
B) closing of the AV valves.
C) opening of the semilunar valves.
D) closing of the semilunar valves.
E) blood rushing through the AV valves during diastole, creating a turbulent flow.

Question 51

The period lasting from closure of the AV valve to opening of the aortic valve is known as

A) isovolumetric ventricular contraction.
B) isovolumetric ventricular relaxation.
C) the rapid ejection phase.
D) the rapid filling phase.
E) none of these answers.

Question 52

The heart valves open and close due to

A) attachment to the heart muscle.
B) a pressure difference on the two sides of the valve.
C) Na+ and K+ fluxes during ventricular depolarization.
D) turbulent flow in the atria and ventricles.
E) none of these answers.

Question 53

What percentage of ventricular filling is normally accomplished before atrial contraction begins?

A) 0%
B) 20%
C) 80%
D) 50%
E) 100%

Question 54

The volume of blood ejected from each ventricle during a contraction is called the

A) end-diastolic volume.
B) end-systolic volume.
C) stroke volume.
D) cardiac output.
E) cardiac reserve.

Question 55

During isovolumetric ventricular contraction,

A) rapid filling of the ventricles occurs.
B) all heart valves are closed
C) the maximum volume of blood is ejected.
D) the maximum rate of ejection occurs.
E) the atria are in systole

Question 56

Vagal influences on the heart result in

A) enhanced calcium permeability at the SA node.
B) enhanced potassium permeability at the SA node.
C) less frequent depolarization of the SA node.
D) both (a) and (b) above.
E) both (b) and (c) above.

Question 57

Cardiac output

A) is the volume of blood pumped by each ventricle during each contraction or beat.
B) is the volume of blood pumped by each ventricle per minute.
C) equals heart rate x stroke volume.
D) both (a) and (c) above.
E) both (b) and (c) above.

Question 58

When the heart is sympathetically stimulated

A) cardiac output decreases
B) acetylcholine is released from neuron.
C) norepinephrine is released onto the SA node and myocardium
D) Ca²⁺ channels open in greater numbers
E) both (c) and (d) above.

Question 59

All of the following decrease overall cardiac function except

A) acetylcholine.
B) NE
C) afterload.
D) parasympathetic activity.
E) vagal activity.

Question 60

The end-systolic volume is

A) the volume of blood in the ventricle when ejection is complete.
B) the volume of blood in the ventricle when filling is complete.
C) always equal to the stroke volume.
D) the volume of blood in the ventricle when ejection is complete and always equal to the stroke volume.
E) the volume of blood in the ventricle when filling is complete and always equal to the stroke volume.

Question 61

The term systole means

A) closure.
B) conduction.
C) contraction.
D) opening.
E) relaxation.

Question 62

Which molecule(s) induce vasodilation of coronary arteries?

A) adenosine.
B) adenosine triphosphate.
C) nitric oxide.
D) both (a) and (b) above.
E) all these answers.

Question 63

According to the Frank-Starling law of the heart,

A) the shorter the initial length of the cardiac muscle fibers prior to contraction the more forceful will be the subsequent contraction, because the fibers 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 of 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 only pumps blood to the lungs, whereas the left side must pump blood to the rest of the body.
E) the greater the stroke volume, the smaller will be the subsequent end-diastolic volume because as more blood is squeezed out, the heart cannot fill as completely.

Question 64

The term diastole means

A) closure.
B) conduction.
C) contraction.
D) opening.
E) relaxation.

Question 65

If the cardiac output is 4,800 ml/min, heart rate is 60 beats per minute, EDV is 140 ml. What is ESV?

A) 60
B) 70
C) 80
D) 120
E) 140

Question 66

If the cardiac output is 4,800 ml/min and the heart rate is 60 beats per minute, the stroke volume averages ____ ml.

A) 60
B) 70
C) 80
D) 120
E) 140

Question 67

During heart failure,

A) the Frank-Starling curve is shifted to the left.
B) the heart pumps out a smaller stroke volume than normal for a given end-diastolic volume.
C) a compensatory increase in sympathetic activity increases the contractility of the heart to normal in the early stages of the disease.
D) both (b) and (c) above.
E) all of these answers.

Question 68

If the EDV were held constant, increased stroke volume could be accomplished by

A) increased sympathetic nerve activity to the heart.
B) increased parasympathetic nerve activity to the heart.
C) decreased contractility.
D) sleep.
E) increased arterial blood pressure.

Question 69

Which of the following will not increase stroke volume?

A) increased end-diastolic volume
B) increased contractility of the heart
C) increased end-systolic volume
D) increased stretch of the cardiac muscle fibers during ventricular filling
E) increased venous return

Question 70

Sympathetic stimulation of the heart

A) increases the heart rate.
B) increases the contractile strength of the heart muscle.
C) shifts the Frank-Starling curve to the left.
D) two of these answers.
E) all of these answers.

Question 71

A whistling murmur heard between the second and first heart sound would be indicative of

A) a stenotic AV valve.
B) an insufficient AV valve.
C) a stenotic aortic or pulmonary semilunar valve.
D) an insufficient aortic or pulmonary semilunar valve.
E) no conclusions can be reached based on the information provided.

Question 72

If stroke volume is 80 ml and the heart rate is 70 beats per minute, the cardiac output is

A) 150 l/min
B) 560 ml/min
C) 5,600 ml/min
D) 8,700 ml/min
E) none of these answers.

Question 73

Parasympathetic innervation to the heart

A) is the vagus nerve.
B) decreases the rate at which spontaneous action potentials are initiated in the SA node.
C) decreases the strength of ventricular contraction.
D) both (a) and (b) above.
E) all of these answers.

Question 74

The cardiac muscle

A) extracts oxygen and nutrients from the blood within its chambers.
B) receives its blood supply primarily during ventricular systole when blood is forced into the vessels supplying the heart.
C) 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) receives most of its blood supply during ventricular diastole by means of the coronary circulation.
E) none of these answers.

Question 75

Blood flow through the coronary circulation occurs

A) mainly during systole.
B) mainly during diastole.
C) almost equally during systole and diastole.
D) only during ventricular isovolumetric contraction.
E) none of these answers.

Question 76

Which heart component is influence by NE but not by ACh?

A) ventricular.
B) AV node.
C) heart rate.
D) SA node.
E) none of the above

Question 77

The ____ nerves to the heart alter cardiac output by decreasing heart rate.

A) motor.
B) sensory.
C) sympathetic.
D) vagus
E) none of these answers.

Question 78

Select the cranial nerve of the parasympathetic nervous system that signals the heart.

A) cardiac.
B) coronary.
C) hypoglossal.
D) trigeminal.
E) vagus.

Question 79

At rapid heart rates,

A) the lengths of systole and diastole shorten equally.
B) the length of systole stays almost constant, but the length of diastole shortens considerably.
C) the length of systole increases at the expense of diastolic time shortening.
D) diastolic time lengthens, and systolic time shortens.
E) none of these answers.

Question 80

An insufficient AV valve

A) fails to open completely.
B) fails to close completely.
C) produces a gurgling diastolic murmur.
D) fails to open completely and produces a gurgling diastolic murmur.
E) fails to close completely and produces a gurgling diastolic murmur.