Chapter 17: Cardiovascular System
EKG Graph
1. A: The atria depolarize. 2. D: The action potential is in the AV node. 3. F: The ventricles depolarize 4. B: The ventricles repolarize. 5. G: The ventricles are contracting. 6. H: The time from ventricular depolarization to the end of ventricular repolarization, including ventricular contraction.
End-diastolic volume (EDV) for each ventricle at the end of atrial systole is normally about:
120 ml.
A patient has a heart rate of 70 beats per minute, an EDV of 110 ml, and an ESV of 70 ml. What is the patient's cardiac output?
2.8 L/minute SV = (EDV - ESV)/beat => 40 mL/beat; Cardiac output= SV X HR => 40 mL/beat X 70 beats/minute
Place the following parts of the cardiac conduction system in the order in which they transmit the action potential.
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 heart beat
Calculate the stroke volume (SV) of a patient whose EDV is 140 milliliters and whose ESV is 60 milliliters.
80 milliliters SV = EDV - ESV
Calculate the cardiac output if heart rate (HR) is 90 beats per minute, stroke volume (SV) is 110 ml/beatml/beat, end diastolic volume (EDV) is 140 mlml, and end systolic volume (ESV) is 30 mlml.
9.9 L/min Cardiac output is the product of heart rate times stroke volume.
Identify the wave representing depolarization of all cells within the atria except the SA node.
A
The mitral or bicuspid valve closes at _________.
A
Which of these structures conduct(s) action potentials the slowest?
AV node
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
If Jerome is having an acute MI, which ECG change would you expect to see?
An elevated ST segment
Heart rate, stroke volume, and cardiac output are dependent on one another; these relationships can provide many clues as to why Jean fainted during her workout session. Which of the following events could lead to a decrease in cardiac output that could increase Jean's risk of fainting
An increase in afterload.
How might coronary artery anastomoses help a patient with a coronary artery disease?
Anastomoses provide an alternate route of blood flow around a coronary artery that may be blocked.
Suppose that Jean did suffer an MI due to a blockage in her left coronary artery. The blockage would also impair blood flow through the:
Anterior interventricular artery and the circumflex artery.
Identify the ear like flaps that are attached to the top chambers of the heart.
Auricle
Identify the T wave.
B
right atrium
B
So why is Mr. G's mitral regurgitation causing a systolic murmur? Remember, a murmur is caused by abnormal turbulent blood flow.
Because his mitral valve leaks, when the ventricles contract, they push blood back up through it into the left atrium.
Identify the valve found between the left atrium and left ventricle.
Bicuspid (mitral) valve
By what mechanism would an increase in venous return increase stroke volume?
By what mechanism would an increase in venous return increase stroke volume?
Identify the interval that can be used to measure heart rate.
C
The plateau phase of the cardiac action potential is due to __________.
Ca2+ influx
What fibrous structure functions to anchor the atrioventricular valves in a closed position?
Chordae tendineae
Which of the following can be heard with a stethoscope most easily?
Closing of atrioventricular valves
Bundle branches
Convey(s) the impulse down the interventricular septum
Purkinje fibers
Convey(s) the impulse throughout the ventricular walls
Identify the complex representing ventricular depolarization.
D
Certain drugs used to treat dysrhythmias, called local anesthetics, work by blocking voltage gated sodium ion channels and slowing the entry of sodium ions into the cell during an action potential. What effects would you see?
Decrease depolarization of the cell
AV node
Delay(s) occurs here while atria contract
Which of these terms is best defined an influx of positive charges, causing the resting membrane potential to become less negative, i.e., more positive?
Depolarization
Identify the S-T segment.
E
pulmonary trunk.
E
AV bundle
Electrical link(s) between atria and ventricles
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
Oxygenated blood flows through the right side of the heart.
False
Stroke volume (SV) can be calculated by subtracting the end-diastolic volume (EDV) from the end-systolic volume (ESV).
False
The base of the heart is located at the bottom of the heart.
False
The moderator band is found on both the right and left side of the heart.
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
mitral (bicuspid) valve.
G
Jean was familiar with the fact that her heart pumped blood throughout her body; that was common knowledge. She was fascinated to learn how her heart and lungs worked together so intimately, a fact with which she was not familiar. Which of the following statements best describes the process of gas exchange and its relationship with the heart?
Gas exchange takes place when oxygen diffuses into and carbon dioxide diffuses out of the blood entering the alveoli from the right ventricle.
Which of the following would happen to cardiac output if sympathetic nervous system stimulation of the heart had positive chronotropic effects only?
Heart rate would increase, and cardiac output would decrease.
papillary muscle.
I
Jean has been admitted to the CCU with a preliminary diagnosis of AFib with RVR. The initial objective of the cardiologist is to slow Jean's heart rate down enough to make a definitive diagnosis of atrial fibrillation. Where does the electrical sequence of events that leads to each heartbeat begin?
In the SA node because it has the fastest intrinsic rate of depolarization.
The drug digoxin increases the concentration of intracellular calcium ions in cardiac muscle cells. Select what effect you would see.
Increase in stroke volume
Which of the following factors may contribute to an increase in stroke volume?__________.
Increase preload and contractility, and decrease afterload
If the ventricles were diseased and failing to pump adequately, the end-systolic volume would _____ and in turn, this would cause the end-diastolic volume to ______.
Increase; decrease
How will the cardiac output change if you double the heart rate but reduce the stroke volume by one-half?
It will not change.
left ventricle.
J
interventricular septum.
K
Heart tissue dies during a myocardial infarction (MI), and a person's survival and recovery depend on the extent of cell death and the chamber(s) involved. In which chamber would the loss of function be most damaging to survival?
Left Ventricle
What heart chamber pushes blood through the aortic semilunar valve?
Left ventricle
internodal pathways
Link(s) between the SA node and AV node
Which of the following valves would be affected if papillary muscles and/or chordae tendinae stopped functioning?
Mitral valve
Which of the following is correct about the filling of the ventricles?
Most blood flows passively into the ventricles through open AV valves.
Sometimes health care providers will elect not to treat conditions such as atrial fibrillation in which there is no functional atrial contraction. Select the logic behind this.
Most of the blood drains from the atria passively into the ventricles.
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.
Name the ridged bundles of muscle found projecting inside the right atrium.
Pectinate muscles
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.
What is the function of the coronary circulation?
Provide a blood supply to the heart
Identfiy the valve located at the exit of the right ventricle.
Pulmonary semilunar valve
A damaged right bundle branch will prevent the passage of the action potential to the:
Purkinje fibers in the right ventricle.
A person notices his or her heart beat because he or she senses blood being pumped by the heart. Excessive caffeine intake can lead to irregular heart rhythms (arrhythmias) that patients perceive as "skipped beats." Given that caffeine is a stimulant, which of the following mechanisms best explains the reason for the feeling that the heart skipped a beat?
Purkinje fibers initiate spontaneous action potentials, which cause the ventricles to contract early.
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
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 chamber of the heart exits into the pulmonary trunk?
Right ventricle
The main pacemaker of the heart is the __________.
SA node
Which part of the conduction system initiates the depolarizing impulse, which spreads throughout the heart?
SA node
Which part of the intrinsic conduction system normally initiates the depolarizing impulse that causes a heartbeat?
SA node
Arrange these elements of the intrinsic conduction system in the order that a depolarizing impulse travels during a normal heartbeat.
SA node Internodal pathways AV node AV bundle Bundle branches Purkinje fibers
SA node
Set(s) the pace for the entire heart
Before Baby A was born, she was not sending much blood to her lungs. Instead, the blood passed through the septal defect into the left atrium, which sent it to the left ventricle and to her body. But why didn't the baby die if no blood was going through her lungs?
She was getting her oxygen from the placenta, not from breathing.
Which type of treatment might Jerome receive once the MI is confirmed? Select all the correct answers.
Supplemental oxygen Nitroglycerin Pain medication
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 effects would one see if the Q-T interval is prolonged?
The action potential would last for a longer duration.
Which of the following happens immediately after the P wave?
The atria contract.
Now that you have reviewed normal blood flow, why does a patient with left-sided heart failure have a low systolic blood pressure?
The left side of the heart pumps blood into the body, so when it fails, less blood will be pumped into the arteries.
When you listened to his lungs you heard fluid in them. Could this be due to his heart failure, or is it another problem?
The left side of the heart receives blood from the lungs and pumps it out to the body, so if it fails, blood will remain in the lungs.
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 activity is occurring in the heart during the Q-T interval on an electrocardiogram (ECG)?
The ventricular cells are undergoing action potentials.
The transesophageal echocardiogram, or TEE, allows a real-time view of the cardiac cycle as blood flows from atria to ventricle and from ventricle to great vessel. One must understand how the heart works under normal conditions to appreciate the effects of a disorder, AFib in this case. Which of the following statements is false with regard to the phases of the cardiac cycle under normal conditions?
The ventricular ejection phase is characterized by the end-systolic volume (ESV), an event in which blood neither enters nor exits the ventricles, which completes one cardiac cycle.
Which of the following effects will one see if there is a right-sided heart failure (failure of the right ventricle to pump adequately)?
There will be a backflow of blood from the left ventricle into the left atrium. There will be low levels of oxygen in the blood.
As their name suggests, calcium ion channel blockers block calcium ion channels in the sarcolemma of pacemaker and contractile cardiac muscle cells and slow calcium ion entry into the cell during an action potential. What effects would these drugs have on the myocardial cells?
There would be a decrease in contractility
Jerome also had blood work done to confirm the MI. The presence of troponin, or cardiac enzymes such as CK-MB, are a positive indicator of an MI. Why is their presence at higher levels in the blood indicative of an MI?
These proteins are normally found inside cardiac muscle cells and if present in the blood indicate damage to the cells.
Name the irregular ridges of muscle lining the ventricles.
Trabeculae carneae
Identify the right atrioventricular valve.
Tricuspid valve
Blood on the right never mixes with blood on the left, once the heart is fully developed.
True
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 first branch off the arch of the aorta is the brachiocephalic artery in both the sheep and the human.
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
The sympathetic nervous system increases cardiac output by increasing both heart rate and stroke volume.
True
According to the Frank-Starling law, a bigger preload will result in __________.
a stronger contraction
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.
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 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
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 (AV) valve
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.
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 (CO)
Autorhythmicity in the heart is the responsibility of:
cardiac pacemaker cells.
The cusps of the atrioventricular valves attach to the papillary muscles via the __________.
chordae tendineae
The beginning of the QRS complex of the electrocardiogram (ECG) immediately precedes which of the following events?
closing of the atrioventricular valves
An increase in sympathetic stimulation of the heart would increase stroke volume by increasing __________.
contractility
Inotropic agents affect:
contractility
Generally, coronary veins empty into a vessel known as the:
coronary sinus.
Which of the following is not an effect of the sympathetic nervous system?
decrease in heart rate
Digoxin is a positive inotropic agent derived from the foxglove family of plants. Which of the following is an effect of digoxin?
decreased ESV
How would a decrease in blood volume affect both stroke volume and cardiac output?
decreased stroke volume and no change in cardiac output
Hemorrhage would lead to a __________ preload and therefore __________ cardiac output.
decreased; decreased
The electrical impulse is __________ as it passes through the AV node, which permits the atria to contract __________ ventricles.
delayed; before
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 maximum amount of blood in the ventricles at the end of the ventricular filling phase is called __________.
end-diastolic volume
What largely determines preload?
end-diastolic volume (EDV)
Name the inner lining of the heart.
endocardium
The visceral pericardium is also known as the __________.
epicardium
The visceral pericardium is the same as the:
epicardium
Which of the following would increase heart rate?
epinephrine and norepinephrine
When threshold is reached at the SA node (an autorhythmic cell), what channels open causing further depolarization of the membrane?
fast calcium
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
In Baby A, the atrial septal defect did not close at birth. Blood is flowing through her defect in what direction?
from the left atrium into the right atrium
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.
Action potentials generated by the autorhythmic cells spread to the contractile cells through what structures in the membrane?
gap junctions
What causes the aortic semilunar valve to close?
greater pressure in the aorta than in the left ventricle
The concentration gradient for calcium ions...
has the same direction as the concentration gradient for sodium ions.
Coronary circulation involves the delivery of oxygenated blood to the:
heart
Jerome will probably be placed on medication to decrease the workload of his heart and give it time to reset and recover. Remember that, once damaged, cardiac muscle does not repair via regeneration; it forms scar tissue that does not work normally. Which medication(s) might be prescribed to Jerome?
holesterol-lowering drugs to decrease the cholesterol and triglycerides in the blood. Beta (ββ) blockers, which block the beta receptor in cardiac muscle to prevent heart rate from increasing. The heart beats slower and with more force .Ca++ channel blockers to decrease the strength of the heart's contraction and to vasodilate blood vessels. Anticoagulants such as aspirin or heparin. They decrease the blood's ability to clot and are known as blood thinners (although they don't actually make the blood thinner).
How would an increase in the sympathetic nervous system increase stroke volume?
increased contractility
Which of the following would increase cardiac output to the greatest extent?
increased heart rate and increased stroke volume
The apex of the heart is __________.
inferior
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
Unlike skeletal muscle action potentials, cardiac muscle action potentials __________.
involve calcium voltage-gated channels
Ventricular systole begins during the __________ phase of the cardiac cycle.
isovolumetric contraction
As ventricular systole begins, all four heart valves are closed during the:
isovolumetric contraction phase.
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
The left ventricle is the chamber with the thickest wall, because:
it has to generate enough pressure to pump blood throughout the entire systemic circuit
Blood returning from the lungs enters the __________.
left atrium
Which heart chamber receives blood from the pulmonary veins?
left atrium
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
Identify the most muscular chamber.
left ventricle
Rheumatic fever is a complication of untreated strep throat and the biggest cause of valve disorders. It can cause a condition caused aortic regurgitation in which the aortic semilunar valve is damaged and blood flows backwards into the:
left ventricle
The cardiac chamber with the thickest wall is the __________.
left ventricle
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 located _________.
mediastinum
The heart is situated in the middle of the thoracic cavity in a region known as the:
mediastinum
As part of a blood drive on campus for the American Red Cross, you and your friends have just donated 500 mlml of blood. You are now relaxing at the student lounge, waiting for A&P lab to begin. Unfortunately, even though you are thirsty, you haven't bothered to buy yourself a drink. Other than a little soreness of the skin and tissue around your median cubital vein, you feel fine. How has your 500 mlml decrease in blood volume most likely affected your cardiac output, heart rate, and stroke volume?
no change in cardiac output, increased heart rate, decreased stroke volume
Which of these is not a feature of cardiac muscle tissue?
non-striated
The cells that rhythmically and spontaneously generate action potentials in the heart are called __________.
pacemaker cells
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
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
A contractile cell with a sustained membrane potential of 0 mV is experiencing the:
plateau phase.
One of the changes that occurs in the pacemaker potential (unstable resting membrane potential) in the SA node (an autorhythmic cell) is a decreased efflux of what ion?
potassium
The degree of stretch experienced by the sarcomeres in the ventricle cells before they contract is called:
preload
The AV valves close when __________.
pressure in the ventricles increases
What is the function of the valves in the heart?
prevent backflow of blood through the heart
The left side of the heart receives blood returning from the:
pulmonary circuit
Blood that leaves the right ventricle enters the __________.
pulmonary trunk
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
What is the ligamentum arteriosum?
remnant of ductus arteriosus
Which chamber receives blood from the superior and inferior vena cavae?
right atrium
Blood in the right ventricle arrived from the:
right atrium.
Which heart chamber pumps unoxygenated blood out the pulmonary trunk?
right ventricle
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 right and left atria depolarize and contract following the arrival of the action potential from the:
sinoatrial (SA) node.
The anatomy of the intrinsic conduction system causes contraction of the ventricles to begin at the apex and move superiorly. Why is this important?
so blood is forced upward, toward the semilunar valves
What two values are needed in order to calculate cardiac output (CO) for a ventricle?
stroke volume (SV) and heart rate (HR)
The volume of blood pumped by each ventricle in one heartbeat is known as:
stroke volume (SV).
The vessels that deliver oxygen to the tissues of the body are part of the __________.
systemic circuit
Right ventricular heart failure prevents the right ventricle from efficiently plumping blood into the pulmonary circuit, thus creating a backup of blood into the right atrium and the:
systemic veins
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.
In order to cause cardiac muscle contraction, the contractile cells must also depolarize. What causes the depolarization of the contractile cells?
the flow of positive ions from adjacent cells
Afterload is described as:
the force the ventricles must overcome to eject blood into their respective arteries.
Heart Rate (HR)
the number of heart beats per minute
The aortic valve closes when __________.
the pressure in the left ventricle falls below aortic pressure
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
End Systolic Volume (ESV)
the volume of blood in one ventricle after contraction
End diastolic volume (EDV)
the volume of blood in one ventricle before contraction
Stroke volume (SV
the volume of blood per heart beat pumped out by one ventricle
Venous return (VR)
the volume of blood per minute flowing into one atrium
Cardiac output (CO)
the volume of blood per minute pumped out by one ventricle
What valve prevents the backflow of blood from the right ventricle into the right atrium?
tricuspid
The valve located between the right atrium and the right ventricle is the:
tricuspid AV valve
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
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
The right atrium receives blood from the:
vena cavae
Blood from the systemic circuit returns to the heart via the __________.
venae cavae
The chambers that have just emptied when the second heart sound is heard are the __________.
ventricles
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
During what phase does blood flow from the ventricles into the pulmonary trunk and aorta?
ventricular ejection phase
The T wave of an ECG corresponds to __________.
ventricular repolarization
Repolarization of an autorhythmic cell is due to the opening of which channels?
voltage-gated potassium channels
