Ch 17 Heart
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:
50 mL
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
Calculate the cardiac output if the heart rate is 100 beats per minute and the stroke volume is 65 ml.
6500 mL/min
How much blood is pumped from each ventricle during the ventricular ejection phase?
70 mL
Stroke volume averages about:
70 ml per heartbeat
Identify the wave representing depolarization of all cells within the atria except the SA node.
A
Match the following with the waves, segments, or intervals on the electrocardiogram (ECG). Identify the wave representing depolarization of all cells within the atria except the SA node.
A
Identify the right atrium
B
Match the following with the waves, segments, or intervals on the electrocardiogram (ECG). Identify the T wave
B
Identify the interval that can be used to measure heart rate.
C
Identify the complex representing ventricular depolarization.
D
Identify the S-T segment.
E
Match the following structures with the internal heart anatomy. Identify the pulmonary trunk
E
Pulmonary Trunk
E
Identify the P-R interval.
F
Desmosomes present between adjacent cardiac muscle cells allow ions to rapidly pass from one cell to another, permitting communication among cardiac muscle cells.
False
From superficial to deep, the pericardial sac consists of the fibrous pericardium, visceral pericardium, parietal pericardium, and the epicardium.
False
Stroke volume (SV) can be calculated by subtracting the end-diastolic volume (EDV) from the end-systolic volume (ESV).
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
Identify the interval representing the entire duration of a ventricular action potential.
G
Identify the mitral (bicuspid) valve
G
Match the following with the waves, segments, or intervals on the electrocardiogram (ECG). Identify the interval representing the entire duration of a ventricular action potential.
G
identify the papillary muscle
I
As ventricular systole begins, all four heart valves are closed during the:
Isovolumetric contraction phase
identify the left ventricle
J
Identify the interventricular septum.
K
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
On an electrocardiogram (ECG), atrial repolarization is obscured by the:
QRS wave
Which part of the electrocardiogram (ECG) would most be affected by abnormally slow depolarization of the ventricles?
QRS wave
Which wave on the electrocardiogram (ECG) represents ventricular depolarization?
QRS wave
Which of the following can be used to measure heart rate?
R-R interval
What wave on the electrocardiogram (ECG) occurs during the ventricular ejection phase of the cardiac cycle?
T wave
Predict the position of the valves during the ventricular ejection phase.
The AV valves are shut while both semilunar valves are forced open
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.
What activity is occurring in the heart during the Q-T interval on an electrocardiogram (ECG)?
The ventricular cells are undergoing action potentials
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 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 left ventricle has greater muscle mass than the right ventricle since it pumps against greater resistance.
True
The sinoatrial (SA) node fires more rapidly at higher body temperatures, increasing cardiac output.
True
Which of the following is a chronotropic agent that decreases heart rate?
acetylcholine
The long length of the cardiac action potential, at 200-300 msec, allows for:
an opportunity for the heart to fill with blood
The right and left coronary arteries receive blood from the:
aorta
What vessel delivers oxygenated blood to systemic capillaries for gas exchange?
aorta
Where should the left ventricle send blood?
aorta
Which vessel supplies the systemic circuit with oxygenated blood?
aorta
The P wave on an electrocardiogram (ECG) represents the depolarization of cells in the:
atria
Which hormone decreases cardiac output by decreasing blood volume and preload?
atrial natriuretic peptide (ANP)
What is NOT part of the cardiac conduction system?
atrioventricular valve
Which valve is situated between the left atrium and left ventricle?
bicuspid valve
The coronary sinus does NOT receive blood from the:
brachiocephalic vein
How do cardiac cells sustain a membrane potential of around 0 mV during the plateau phase?
calcium channels remain open
Which of the following volumes should be the greatest?
cardiac output
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 largely determines preload?
end-diastolic volume (EDV)
The visceral pericardium is the same as the:
epicardium
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
Coronary circulation involves the delivery of oxygenated blood to the:
heart
What ion movement changes the membrane potential in a contractile cell from negative to positive during the rapid depolarization phase?
influx of sodium ions
What characteristic differentiates cardiac muscle cells from skeletal muscle cells?
intercalated discs
What surface groove separates the right and left ventricles?
interventricular sulcus
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
The apex of the heart is situated toward the:
left hip
Which chamber experiences a maximum pressure of around 118 mm Hg during contraction?
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
What muscles, present in the ventricles, anchor the atrioventricular valves by tendon-like chords called chordae tendineae?
papillary muscles
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
A contractile cell with a sustained membrane potential of 0 mV is experiencing the:
plateau phase
During what phase of the action potential will calcium ions enter the contractile cell as potassium ions exit?
plateau phase
What do pacemaker cell action potentials lack?
plateau phase
The degree of stretch experienced by the sarcomeres in the ventricle cells before they contract is called:
preload
What is the function of the valves in the heart?
prevent backflow of blood through the heart
Which vessel is guarded by a semilunar valve at its base?
pulmonary trunk
Which of the following does NOT return blood to the right atrium of the heart?
pulmonary vein
Which of the following vessels carries oxygenated blood?
pulmonary vein
What vessel(s) deliver oxygenated blood to the left atrium?
pulmonary veins
A damaged right bundle branch will prevent the passage of the action potential to the:
purkinje fibers in the right ventricle
Blood in the right ventricle arrived from the:
right atrium
The right and left atria depolarize and contract following the arrival of the action potential from the:
sinatrial (SA) node
What normally serves as the pacemaker of the entire heart?
sinoatrial (SA) node
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
The volume of blood pumped by each ventricle in one heartbeat is known as:
stroke volume
What two values are needed in order to calculate cardiac output (CO) for a ventricle?
stroke volume and heart rate
Archie has a resting heart rate of 125 beats per minute. Classify his cardiac dysrhythmia.
tachycardia
As a result of the long refractory period in the contractile cell, cardiac muscle can NOT exhibit:
tetany
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
Determine the impact if the connection between the sinoatrial (SA) node and the atrioventricular (AV) node becomes blocked.
the ventricles will contract more slowly
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
The sympathetic nervous system increases cardiac output by increasing both heart rate and stroke volume.
true
Which cranial nerves have a negative chronotropic effect on heart rate?
vagus nerves (CN X)
Both the left and right atria receive blood from:
veins
During what phase does blood flow from the ventricles into the pulmonary trunk and aorta?
ventricular ejection phase
