Deck 13: The Cardiovascular System: Cardiac Function

Question 1

What is the primary function of the AV and semilunar valves?

A) to coordinate the autorhythmic movements of the heart
B) to keep the right and left sides of the heart separated
C) to control the speed at which blood enter and leaves the heart
D) to permit blood to flow forward while preventing it from flowing backward
E) The opening and closing of the valves creates the normal patterns of an EKG.

Answer 1

D

Question 2

Which of the following statements best describes the function of the chordae tendineae?

A) They pull downward on the valve cusps, thereby preventing the AV valves from being pushed into the atria (prolapsing).
B) They open and close the AV valve due to the movement of the papillary muscle during contraction.
C) The chordae tendineae generate autorhythmicity within the heart.
D) The chordae tendineae act like a parachute and capture blood as it enters the right ventricle.
E) When the heart contracts, the chordate tendineae separate the flow of blood from the right and left sides of the heart.

Answer 2

A

Question 3

What structure separates the thoracic cavity from the abdominal cavity?

A) diaphragm
B) heart
C) lungs
D) intestines
E) liver

Answer 3

A

Question 4

Which of the following is the correct conduction pathway through the heart?

A) SA node, Purkinje fibers, AV node, bundle of His, bundle branches
B) SA node, AV node, bundle of His, bundle branches, Purkinje fibers
C) AV node, SA node, bundle branches, bundle of His, Purkinje fibers
D) Purkinje fibers, bundle of His, bundle branches, SA node, AV node
E) Bundle of His, bundle branches, Purkinje fibers, SA node, AV node

Question 5

Which of the following statements best describes a portal system?

A) The portal system allows enough pressure to be generated to close the foramen ovale in the fetal heart.
B) The portal system refers to ports located in the veins (which does not allow for the backflow of blood).
C) Blood flows from one capillary bed to another, bypassing general circulation.
D) Blood flows in one direction throughout the circulatory system.
E) The portal system is the same as parallel flow.

Question 6

Blood supply to the heart comes from

A) aorta.
B) coronary arteries.
C) cerebral arteries.
D) blood within the atria.
E) blood within the ventricles.

Question 7

What two major regions of the heart contain a concentration of pacemaker cells?

A) sinoatrial node and Purkinje fibers
B) bundle of His and Purkinje fibers
C) bundle of His and atrioventricular node
D) sinoatrial node and bundle of His
E) sinoatrial node and atrioventricular node

Question 8

Conduction through which of the following is slow to allow atria to contract before the ventricles?

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

Question 9

Although blood is a fluid, nearly half its volume is composed of cells. The most numerous cells are . The remainder of the cells are foreign particles and microorganisms.
, which help the body defend itself against

A) erythrocytes : leukocytes
B) leukocytes : erythrocytes
C) platelets : leukocytes
D) erythrocytes : platelets

Question 10

The primary site of exchange between blood and interstitial fluid occurs across what type of blood vessel?

A) veins
B) venules
C) capillaries
D) arterioles
E) arteries

Question 11

The opening and closure of the atrioventricular and semilunar valves is driven by

A) differences in pressure across the valve.
B) contraction of the valve.
C) contraction of the ventricle and atria that pull the valves into place.
D) contraction and relaxation of the valve.
E) contraction of muscles attached to the valves.

Question 12

Whereas the contractile activity of skeletal muscle is called , that of cardiac muscle is because the contraction originates within the musculature itself.

A) somatic : autorhythmic
B) voluntary : involuntary
C) neurogenic : myogenic
D) somatic : autonomic
E) extrinsic : intrinsic

Question 13

When blood moves through the body it travels in a circular pattern. The general pattern of blood flow follows which sequence of vessels as it leaves the heart?

A) arterioles, arteries, capillaries, venules, veins
B) veins, venules, capillaries, arterioles, arteries
C) arteries, veins, venules, arterioles, capillaries
D) veins, capillaries, venules, arterioles, arteries
E) arteries, arterioles, capillaries, venules, veins

Question 14

Which chamber of the heart has the thickest musculature?

A) left atrium
B) right atrium
C) left ventricle
D) right ventricle
E) Both ventricles have equal thickness and are thicker than the atria.

Question 15

Keeping blood on the left side of the heart from mixing with the blood on the right side is a function of what structure(s)?

A) septum
B) apex
C) arteries
D) valves
E) chordae tendineae

Question 16

The term autorhythmicity refers to the heart's ability to

A) generate its own contractile cycle.
B) intrinsically modify its contractility.
C) conduct action potentials along the conduction pathway.
D) originate its contraction neurogenically.
E) act as a functional syncytium.

Question 17

Closure of the atrioventricular valve occurs when

A) the atrium contracts.
B) pressure inside the ventricle is greater than pressure inside the atrium.
C) the valve contracts.
D) pressure inside the ventricle is less than pressure inside the atrium.
E) the papillary muscle contracts.

Question 18

What structure provides the pathway for the movement of electrical current between the cells of the conduction pathway and the ventricular muscle fibers?

A) desmosomes
B) potassium channels
C) funny channels
D) gap junctions
E) sodium channels

Question 19

Which statement best describes parallel flow in the circulatory system?

A) Parallel flow refers to the flow of blood just to the heart itself, which keeps it oxygenated at all times.
B) In the systemic circuit blood flows from one organ directly to the next, hence in parallel.
C) Parallel flow refers to the flow of electrical impulses in the heart.
D) The organs of the body are arranged in a parallel circuit to allow adequate flow and pressure to all body systems and maintain homeostasis of blood pressure.
E) Parallel flow refers to deoxygenated blood only and not to oxygenated blood.

Question 20

The circulatory system consists of two divisions and is supplied with blood by different sides of the heart. The right heart supplies blood to the circuit, whereas the left heart supplies blood
To the _ circuit.

A) oxygenated : deoxygenated
B) systemic : pulmonary
C) pulmonary : systemic
D) arterial : venule
E) superior (upper body) : inferior (lower body)

Question 21

Why do AV nodal cells NOT determine the heart rate under normal circumstances?

A) They depolarize slower than all other conducting fibers.
B) They slow conduction of the wave of excitation.
C) They depolarize faster than all other conducting fibers.
D) The AV node is connected to the SA node, but not to other conducting fibers in the heart.
E) As depolarization initiated in the SA node reaches the AV node, it leaves the AV node in a refractory state.

Question 22

The T -Q segment is the time from the end of the T wave to the beginning of the QRS complex which measures the time

A) of ventricular systole.
B) between heartbeats.
C) of ventricular diastole.
D) of atrial systole.
E) of atrial diastole.

Question 23

Which of the following components of an ECG represents ventricular depolarization?

A) P wave
B) QRS complex
C) T wave
D) PQ interval
E) TQ segment

Question 24

In an ECG recording, the RR interval is 0.5 seconds. What is the heart rate?

A) 120 beats/min
B) 100 beats/min
C) 50 beats/min
D) 60 beats/min
E) 30 beats/min

Question 25

The R -R interval is the time between the peaks of two successive QRS complexes and represents

A) the amount of time between heartbeats.
B) ventricular systole.
C) atrial diastole.
D) atrial systole.
E) ventricular diastole.

Question 26

Normal resting heart rate is around 70 beats per minute due to the SA node. If the SA node fails, what would you expect the heart beats per minute to be?

A) 10 -20 beats per minute
B) 50 beats per minute
C) 70 beats per minute as the AV node takes over for the SA node
D) If the SA node fails the individual will go into heart failure and therefore there will be no heart rate.
E) 30 -40 beats per minute

Question 27

Which of the following components of an ECG represents atrial depolarization?

A) P wave
B) QRS complex
C) T wave
D) PQ interval
E) TQ segment

Question 28

Which of the following is NOT a part of the excitation -contraction coupling in cardiac muscle?

A) Calcium channels in the sarcoplasmic reticulum open, allowing calcium ions to enter the cytosol.
B) Calcium channels in the plasma membrane open, allowing calcium ions to enter the cell.
C) Calcium opens calcium channels in the sarcoplasmic reticulum.
D) Calcium binds to calmodulin in the cytosol.
E) An action potential travels along transverse tubules.

Question 29

If damage to the AV node slowed down conduction through this tissue, what would be observed on an ECG?

A) a longer P wave
B) a larger P wave
C) an inverted T wave
D) a wider QRS complex
E) a longer PR interval

Question 30

If both the SA node and the AV node fail, what would be the expected outcome of impulse rate within the heart?

A) The rate would be 30 -40 beats per minute due to the concentration of pacemaker cells in the Purkinje fibers.
B) The sympathetic nervous system takes over and maintains normal heart rate.
C) The individual would be in heart failure or have a myocardial infarction due to the lack of a beating heart.
D) The vagus nerve takes over and maintains a normal heart rate.
E) The heart is autorhythmic therefore it continually beats even after death because death is defined as a lack of brain waves.

Question 31

Which of the following is responsible for the repolarization of pacemaker cells?

A) an increase in P_K
B) an increase in P_Ca
C) an increase in P_Na
D) a decrease in P_Na
E) a decrease in P_K

Question 32

What is the function of the sodium -calcium exchanger in cardiac muscle?

A) trigger the release of calcium from the sarcoplasmic reticulum
B) depolarize the cell
C) remove calcium from the cytosol by transporting it to the extracellular fluid thereby relaxing the muscle
D) interact with troponin to initiate cross -bridge cycling
E) remove calcium from the cytosol by transporting it into the sarcoplasmic reticulum

Question 33

Which of the following components of an ECG represents ventricular repolarization?

A) P wave
B) QRS complex
C) T wave
D) PQ interval
E) TQ segment

Question 34

During repolarization (phase 3) of a contractile cell action potential,

A) only sodium permeability is increased.
B) only calcium permeability is increased.
C) only potassium permeability is increased.
D) sodium and calcium permeability are both increased.
E) sodium and potassium permeability are both increased.

Question 35

What causes the rapid depolarization phase of a contractile cell action potential?

A) sodium movement into the cell
B) calcium movement into the cell
C) potassium movement into the cell
D) calcium movement out of the cell
E) sodium movement out of the cell

Question 36

The Q -T interval is the time from the onset of the QRS complex to the end of the T wave which measures

A) the time of atrial systole.
B) the amount of time between each heartbeat.
C) the time of ventricular diastole.
D) the time of ventricular systole.
E) the time of atrial diastole.

Question 37

Which of the following is responsible for the rapid depolarization phase of an action potential within the pacemaker cells?

A) an increase in P_Na
B) a decrease in P_K
C) a decrease in P_Na
D) an increase in P_K
E) an increase in P_Ca

Question 38

Which statement best describes why atrial depolarization is usually not detected on a normal ECG?

A) It occurs at the same time as the QRS complex.
B) The electrodes cannot be placed high enough on the chest to detect the atria.
C) The voltage change in the atria is minimal and therefore does not register on an ECG.
D) The atria are so small and the depolarization happens so quickly that it cannot be detected.
E) The atria do not contract only the AV valves open.

Question 39

The rapid depolarization phase of a pacemaker cell action potential is caused by movement of

A) sodium and calcium through funny channels.
B) calcium through T -type channels.
C) sodium through funny channels.
D) calcium through L -type channels.
E) potassium through funny channels.

Question 40

Which of the following ion channels does NOT participate in the contractile cell action potential?

A) type L calcium channels
B) inward rectifying potassium channels
C) voltage -gated sodium channels
D) type T calcium channels
E) delayed rectifying potassium channels

Question 41

The small increase in ventricular pressure observed late in diastole is caused by

A) ventricular contraction.
B) atrial relaxation.
C) atrial contraction.
D) blood moving into the atria from vena cava.
E) ventricular relaxation.

Question 42

Regulation of the heart (or any organ or tissue) by neural input, circulating hormones, or any other factor originating from outside the organ is referred to as

A) neurogenic
B) voluntary
C) extrinsic
D) myogenic
E) intrinsic

Question 43

The SA node is innervated by the

A) sympathetic nervous system only.
B) somatic nervous system only.
C) parasympathetic nervous system only.
D) sympathetic and parasympathetic nervous systems.
E) sympathetic, parasympathetic, and somatic nervous systems.

Question 44

What causes the sounds that one hears as the heart beats?

A) the turbulence created as the valves close
B) the turbulence created as the valves open
C) the bulk movement of blood into and out of the ventricle
D) the snapping of the valves into the open position
E) the snapping of the valves into a closed position

Question 45

Blood is ejected from the left ventricle once pressure within the

A) ventricle is greater than pressure within the aorta.
B) ventricle is less than pressure within the aorta.
C) ventricle is greater than pressure within the pulmonary artery.
D) ventricle is less than pressure within the pulmonary artery.
E) muscles of the pulmonary semilunar valve relax.

Question 46

Ejection of blood from the right ventricle will continue until

A) pressure in the aorta is less than pressure in the right ventricle.
B) pressure in the pulmonary artery is greater than pressure in the right ventricle.
C) pressure in the pulmonary artery is less than pressure in the right ventricle.
D) the pulmonary semilunar valve contracts, inducing closure.
E) pressure in the aorta is greater than pressure in the right ventricle.

Question 47

Given end -diastolic volume = 130 mL and end -systolic volume = 50 mL, what is the stroke volume and ejection fraction?

A) SV = 80 mL, EF = 0.61
B) SV = 80 mL, EF = 0.38
C) SV = 180 mL, EF = 0.61
D) SV = 180 mL, EF = 0.38
E) SV = 50 mL, EF = 0.61

Question 48

The increased aortic pressure that occurs during systole reflects a(n)

A) increased volume of blood in the aorta.
B) increased resistance of the vasculature.
C) decreased volume of blood within the aorta.
D) decreased resistance of the vasculature.
E) decreased stiffness of the aorta.

Question 49

During which phase of the cardiac cycle are all four heart valves open?

A) ventricular filling
B) isovolumetric relaxation
C) isovolumetric contraction
D) ventricular ejection
E) none

Question 50

Cardiac output is determined by what two variables?

A) heart rate and stroke volume
B) stroke volume and ejection fraction
C) heart rate and ejection fraction
D) end -diastolic volume and end -systolic volume
E) preload and afterload

Question 51

What phase of the cardiac cycle is the heart in when all four valves of the heart are closed and ventricular pressure is building, but is not yet great enough to open a valve?

A) ventricular filling
B) isovolumetric relaxation
C) isovolumetric contraction
D) ventricular ejection
E) none

Question 52

Which of the following structures is poorly innervated by the parasympathetic nervous system and, therefore, an increase in parasympathetic activity has little effect on this structure?

A) atrioventricular node
B) sinoatrial node
C) ventricles
D) conduction pathway
E) Purkinje fibers

Question 53

The volume of blood ejected from the ventricle with each contraction can be described by the equation

A) (stroke volume) -(end -diastolic volume).
B) (ejection fraction) × (end -diastolic volume).
C) (end -diastolic volume) -(end -systolic volume).
D) (end -systolic volume) -(stroke volume).
E) (pulse pressure) -(end -diastolic volume).

Question 54

Which statement best describes why clinicians use a defibrillator?

A) The ventricles of the heart are so large that only a strong current can make them depolarize, which is needed in order for them to contract and get blood to the body.
B) The applied current opens up voltage gated calcium channels in the atria causing the heart to begin a new P wave.
C) The applied current depolarizes all the muscle cells at the same time, returning synchronous electrical activity to the heart.
D) A defibrillator takes the place of the SA node and must be applied every minute to keep the heart rate normal until it regains its strength and beats on its own.
E) The applied current repolarizes the cells of the heart, hence resetting the heart for normal rhythm.

Question 55

During isovolumetric relaxation,

A) the AV and semilunar valves are open and ventricular pressure is decreasing.
B) the AV and semilunar valves are closed and ventricular pressure is decreasing.
C) the AV valves are open, the semilunar valves are closed, and ventricular pressure is decreasing.
D) the AV and semilunar valves are closed and ventricular pressure is increasing.
E) the AV and semilunar valves are open and ventricular pressure is increasing.

Question 56

The end -diastolic volume minus the end -systolic volume is the

A) ejection fraction.
B) cardiac output.
C) total atrial volume.
D) total ventricular volume.
E) stroke volume.

Question 57

Which of the following describes second -degree heart block?

A) The atria no longer contract.
B) There is a longer delay between atrial contraction and ventricular contraction.
C) Not every ventricular contraction is preceded by an atrial contraction.
D) Not every atrial contraction is followed by a ventricular contraction.
E) The ventricles no longer contract.

Question 58

Which of the following is TRUE of the ventricular filling phase of the cardiac cycle?

A) Ventricular pressure is less than aortic pressure.
B) Ventricular pressure is decreasing.
C) All valves in the heart are open.
D) Ventricular pressure is greater than atrial pressure.
E) Ventricular filling occurs during systole.

Question 59

The increase in ventricular volume early in diastole reflects the

A) increased stiffness of the heart.
B) contraction of the atria moving blood into the ventricle.
C) relaxation of the ventricle.
D) passive movement of blood through the atrium and into the ventricle.
E) back -flow of blood from the aorta.

Question 60

What is occurring during ventricular ejection?

A) The AV valves are closed and the semilunar valves are open as blood is leaving the ventricles.
B) The AV valves are open and the semilunar valves are closed as blood is leaving the ventricles.
C) The AV and semilunar valves are closed as ventricular pressure is increasing.
D) The AV valves are open and the semilunar valves are closed as ventricular pressure is. increasing
E) The AV and semilunar valves are open as blood is leaving the ventricles.

Question 61

The preload is approximately the same as the

A) aortic systolic
B) end -diastolic
C) atrial
D) end -systolic
E) aortic diastolic

Question 62

Under resting conditions, heart rate is primarily under the control of what control system?

A) the parasympathetic nervous system
B) the somatic nervous system
C) epinephrine
D) intrinsic mechanisms
E) the sympathetic nervous system

Question 63

Which heart structure receives blood from the pulmonary veins?

A) right atrium
B) left ventricle
C) left atrium
D) right ventricle
E) AV bundle (bundle of His)

Question 64

Which of the following factors determines preload?

A) end -diastolic volume and end -systolic volume
B) heart rate and venous return
C) peripheral resistance and tension
D) the pressure in the aorta and the lungs
E) parasympathetic activity of the ventricles

Question 65

Which of the following decreases heart rate?

A) increase in venous pressure
B) increase in parasympathetic activity
C) increase in filling time
D) increase in stroke volume
E) increase in sympathetic activity

Question 66

Which heart structure receives deoxygenated blood from veins?

A) right atrium
B) left ventricle
C) left atrium
D) right ventricle
E) AV bundle (bundle of His)

Question 67

What chamber empties into the aorta?

A) right atrium
B) left ventricle
C) left atrium
D) right ventricle
E) AV bundle (bundle of His)

Question 68

Which of the following is a FALSE statement about sympathetic activity to the SA node?

A) Norepinephrine binds to beta₁ adrenergic receptors.
B) The rate of spontaneous depolarization is increased.
C) Funny channel opening is enhanced.
D) Potassium channel closing is enhanced.
E) cAMP levels in the pacemaker cells increases.

Question 69

Where is the SA node located?

A) right atrium
B) left ventricle
C) left atrium
D) right ventricle
E) AV bundle (bundle of His)

Question 70

Which of the following variables is NOT involved in determining ventricular preload?

A) atrial pressure
B) central venous pressure
C) afterload
D) venous return
E) filling time

Question 71

An increase in venous return would result in a(n)

A) increase mid -systolic volume.
B) decreased end -systolic volume.
C) decreased end -diastolic volume.
D) increased end -systolic volume.
E) increased end -diastolic volume.

Question 72

An increase in heart rate can be mediated through which of the following?

A) a decrease in parasympathetic nervous activity only
B) a decrease in sympathetic activity only
C) an increase in sympathetic activity only
D) an increase in parasympathetic activity and a decrease in sympathetic activity
E) a decrease in parasympathetic activity and an increase in sympathetic activity

Question 73

Which of the following variables is NOT an intrinsic factor that alters cardiac function?

A) end -systolic volume
B) hormonal stimulation
C) atrial pressure
D) Starling's law
E) preload

Question 74

Which of the following best describes the effect of sympathetic activity on ventricular contractile cells?

A) The rate of contraction and the force of contraction both increase, whereas the rate of relaxation decreases.
B) The rates of contraction and relaxation both decrease, whereas the force of contraction increases.
C) The force of contraction increases, whereas the rates of contraction and relaxation are not affected.
D) The rates of contraction and relaxation both increase, whereas the force of contraction decreases.
E) The rates of contraction and relaxation and the force of contraction all increase.

Question 75

Which of the following describes the effect of end -diastolic volume on stroke volume?

A) A decrease in end -diastolic volume creates a vacuum drawing more blood into the ventricle increasing stroke volume.
B) A decrease in end -diastolic volume allows ventricular muscle cells to relax more during diastole, allowing more blood to return to the heart increasing stroke volume.
C) A decrease in end -diastolic volume allows cardiac muscle to relax, conserving energy for the next contraction, thereby increasing stroke volume of that next contraction.
D) An increase in end -diastolic volume stretches ventricular muscle cells to lengths greater than optimum, decreasing the strength of contraction and thereby decreasing stroke volume.
E) An increase in end -diastolic volume stretches ventricular muscle cells to lengths closer to optimum, increasing the strength of contraction and thereby increasing stroke volume.

Question 76

Which of the following is an effect of parasympathetic activity to the heart?

A) SA nodal cells are depolarized.
B) Heart rate is increased.
C) cAMP is activated.
D) The rate of spontaneous depolarization in SA nodal cells decreases.
E) Postganglionic neurons release acetylcholine, which binds to nicotinic cholinergic receptors in the SA node.

Question 77

A decrease in afterload will lead to which of the following?

A) increased heart rate
B) decreased stroke volume
C) decreased cardiac output
D) increased stroke volume
E) decreased heart rate

Question 78

The mitral valve separates what chamber from its associated ventricle?

A) right atrium
B) left ventricle
C) left atrium
D) right ventricle
E) AV bundle (bundle of His)

Question 79

Starling curves plot against .

A) stroke volume : end -systolic volume
B) heart rate : end -systolic volume
C) stroke volume : end -diastolic volume
D) cardiac output : end -diastolic volume
E) heart rate : end -diastolic volume

Question 80

Which of the following would NOT result from an increase in ventricular contractility?

A) increased ejection fraction
B) increased proportion of end -diastolic volume that is ejected
C) increased stroke volume
D) decreased end -systolic volume
E) decreased end -diastolic volume