Ch 17 Heart
The right and left atria depolarize and contract following the arrival of the action potential from the:
(SA)
What normally serves as the pacemaker of the entire heart?
(SA)
End-diastolic volume (EDV) for each ventricle at the end of atrial systole is normally about:
120 ml.
Place the following parts of the cardiac conduction system in the order in which they transmit the action potential. 1.atrioventricular (AV) bundle 2.Purkinje fibers 3.sinoatrial (SA) node 4.right and left bundle branches 5.contractile cells of cardiac muscle tissue 6.atrioventricular (AV) node
3, 6, 1, 4, 2, 5
The amount of blood remaining in each ventricle at the end of the ventricular ejection phase is normally about:
50ml
Calculate cardiac output if the heart rate is 85 beats/minute, end-diastolic volume (EDV) is 130 ml, and end-systolic volume (ESV) is 60 ml.
5950 ml/min
Calculate the stroke volume (SV) if end-systolic volume (ESV) is 50 ml and the end-diastolic volume (EDV) in a resting heart is 110 ml.
60 ml
Stroke volume averages about:
70 ml per beat
Which part of the intrinsic conduction system delays the impulse briefly before it moves on to the ventricles?
AV node
Increased pressure in the ventricles would close what valve(s)?
AV valves only
The right and left coronary arteries receive blood from the:
Aorta
The P wave on an electrocardiogram (ECG) represents the depolarization of cells in the:
Atria
Identify the interval that can be used to measure heart rate.
C
Identify the right atrium.
D
Stroke volume (SV) can be calculated by subtracting the end-diastolic volume (EDV) from the end-systolic volume (ESV).
False
Identify the papillary muscle.
I
Which of the following is correct about the filling of the ventricles?
Most blood flows passively into the ventricles through open AV valves
Contraction of the atria results from which wave of depolarization on the ECG tracing?
P wave
Which wave on the electrocardiogram (ECG) corresponds with the ventricular filling phase of the cardiac cycle?
P wave
A damaged atrioventricular (AV) bundle or atrioventricular (AV) node will primarily affect the length of the:
P-R interval.
Describe the pressures in the atria and ventricles that would cause the opening of the AV valves
Pressure in the atria would be greater than the pressure in the ventricles.
Which vessel is guarded by a semilunar valve at its base?
Pulmonary trunk
A damaged right bundle branch will prevent the passage of the action potential to the:
Purkinje fibers in the right ventricle.
Which part of the electrocardiogram (ECG) would most be affected by abnormally slow depolarization of the ventricles?
QRS Wave
On an electrocardiogram (ECG), atrial repolarization is obscured by the:
QRS wave
Which of the following can be used to measure heart rate?
R-R interval
Which part of the conduction system initiates the depolarizing impulse, which spreads throughout the heart?
SA node
What best describes the Frank-Starling law?
The Frank-Starling law states that the more the ventricular muscle cells are stretched, the more forcefully they contract.
Heart rate can be determined by measuring the time between two successive R waves on an electrocardiogram (ECG), known as the R-R interval.
True
Pressure in the aorta is greater than pressure in the pulmonary trunk; therefore, the left ventricle has to generate a greater pressure than the right ventricle in order to eject blood from the heart.
True
The left ventricle has greater muscle mass than the right ventricle since it pumps against greater resistance.
True
The sympathetic nervous system increases cardiac output by increasing both heart rate and stroke volume.
True
Which hormone decreases cardiac output by decreasing blood volume and preload?
atrial natriuretic peptide (ANP)
Which valve is situated between the left atrium and left ventricle
bicuspid (mitral) valve
The coronary sinus does NOT receive blood from the:
brachiocephalic vein
Autorhythmicity in the heart is the responsibility of:
cardiac pacemaker cells.
Inotropic agents affect:
contractility.
Generally, coronary veins empty into a vessel known as the:
coronary sinus.
The right side of the heart receives:
deoxygenated blood from the systemic circuit
What does the ECG wave tracing represent?
electrical activity of the heart
The visceral pericardium is the same as the:
epicardium
From superficial to deep, the pericardial sac consists of the fibrous pericardium, visceral pericardium, parietal pericardium, and the epicardium
false
There are two phases of the cardiac cycle in which all four heart valves are open: the isovolumetric contraction phase and the isovolumetric relaxation phase
false
What is the most superficial layer of the pericardial sac?
fibrous pericardium
Which opening in the interatrial septum of the fetal heart connects the right and left atrium?
foramen ovale
The rapid influx of calcium ions into pacemaker cells creates a positive membrane potential inside the cell and is responsible for the:
full depolarization phase.
What causes the aortic semilunar valve to close?
greater pressure in the aorta than in the left ventricle
What characteristic differentiates cardiac muscle cells from skeletal muscle cells?
intercalated discs
What surface groove separates the right and left ventricles?
interventricular sulcus
Put the phases of the cardiac cycle in the correct order, starting after ventricular filling
isovolumetric contraction, ventricular ejection, isovolumetric relaxation
When is the S2 heart sound heard?
isovolumetric relaxation phase
An insufficient mitral valve (bicuspid valve, or left atrioventricular valve) would allow the backflow of blood into the:
left atrium
Which heart chamber receives blood from the pulmonary veins?
left atrium
Which chamber experiences a maximum pressure of around 118 mm Hg during contraction?
left ventricle
Which chamber pumps oxygenated blood out the aorta to the systemic circuit?
left ventricle
The pulmonary circuit involves blood flow from the heart to the
lungs
The heart is situated in the middle of the thoracic cavity in a region known as the:
mediastinum.
Which of the following is NOT a population of pacemaker cells in the heart?
papillary muscles
What is found between the visceral pericardium and the parietal pericardium?
pericardial fluid
During what phase of the action potential will calcium ions enter the contractile cell as potassium ions exit?
plateau phase
A contractile cell with a sustained membrane potential of 0 mV is experiencing the:
plateau phase.
What do pacemaker cell action potentials lack?
plateau phase.
What is the function of the valves in the heart?
prevent backflow of blood through the heart
Which of the following vessels carries oxygenated blood?
pulmonary vein
Which chamber receives blood from the superior and inferior vena cava?
right atrium
Which heart chamber pumps unoxygenated blood out the pulmonary trunk?
right ventricle
Which of the following pacemaker cell populations has the fastest intrinsic rate of depolarization at about 60-70 times or more per minute?
sinoatrial (SA) node
What two values are needed in order to calculate cardiac output (CO) for a ventricle?
stroke volume (SV) and heart rate (HR)
Afterload is described as:
the force the ventricles must overcome to eject blood into their respective arteries.
Which two arteries arise from the right coronary artery?
the right marginal artery and the right posterior interventricular artery
What produces the "lub dub" heart sounds?
the vibrations of the ventricular and blood vessel walls when valves shut
What valve prevents the backflow of blood from the right ventricle into the right atrium?
tricuspid valve
Pressure in the aorta is greater than pressure in the pulmonary trunk; therefore, the left ventricle has to generate a greater pressure than the right ventricle in order to eject blood from the heart.
true
The cardiac conduction system is normally regulated by a population of pacemaker cells known as the sinoatrial (SA) node
true
The left side of the heart is often called the systemic pump due to blood flow to the body.
true
The heart is actually (one, two, or three) pumps?
two pumps
What does the QRS complex represent in the ECG wave tracing?
ventricular depolarization
Isovolumetric relaxation and ventricular filling (two phases of the cardiac cycle) take place during __________.
ventricular diastole