A&P 2 exam 2- heart
Which of these structures conduct(s) action potentials the slowest?
-AV node
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? Select all the correct answers. -Anti-anxiety medication such as valium to decrease Jerome's anxiety and fear of another heart attack. -Oxycodone, a pain killer to reduce the long-term pain from an MI. -Cholesterol-lowering drugs to decrease the cholesterol and triglycerides in the blood. -Ca++ channel blockers to decrease the strength of the heart's contraction and to vasodilate blood vessels. -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. -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).
-Cholesterol-lowering drugs to decrease the cholesterol and triglycerides in the blood. -Ca++ channel blockers to decrease the strength of the heart's contraction and to vasodilate blood vessels. -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. -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).
What percentage of the total number of cardiac muscle cells are pacemaker cells?
1%
Arrange these elements of the intrinsic conduction system in the order that a depolarizing impulse travels during a normal heartbeat.
1) SA node 2) Internodal pathways 3) AV node' 4) AV bundle 5) Bundle branches 6) Purkinje fibers
1. ________: Delay(s) occurs here while atria contract 2. ________: Set(s) the pace for the entire heart 3. ________: Link(s) between the SA node and AV node 4. ________ : Electrical link(s) between atria and ventricles 5. ________: Convey(s) the impulse throughout the ventricular walls 6. ________: Convey(s) the impulse down the interventricular septum
1. AV node: Delay(s) occurs here while atria contract 2. SA node: Set(s) the pace for the entire heart 3. Internodal pathways: Link(s) between the SA node and AV node 4. AV bundle : Electrical link(s) between atria and ventricles 5. Purkinje fibers: Convey(s) the impulse throughout the ventricular walls 6. Bundle branches: Convey(s) the impulse down the interventricular septum
1. ________: the number of heart beats per minute 2. ________: the volume of blood in one ventricle before contraction 3. ________: the volume of blood per heart beat pumped out by one ventricle 4. ________: the volume of blood per minute flowing into one atrium 5. ________: the volume of blood per minute pumped out by one ventricle 6. ________: the volume of blood in one ventricle after contraction
1. Heart rate (HR): the number of heart beats per minute 2. End diastolic volume (EDV): the volume of blood in one ventricle before contraction 3. Stroke volume (SV): the volume of blood per heart beat pumped out by one ventricle 4. Venous return (VR): the volume of blood per minute flowing into one atrium 5. Cardiac output (CO): the volume of blood per minute pumped out by one ventricle 6. End systolic volume (ESV): the volume of blood in one ventricle after contraction
Let's review the electrical events that occur during a heartbeat. Match each phase of the ECG in the figure with its description. 1.) ___: the atria depolarize 2.) ___: the action potential is in the AV node 3.) ___ the ventricles depolarize 4.) ___: the ventricles repolarize 5.) ___the ventricles are contracting 6.) ___ the time from ventricular depolarization to the end of ventricular depolarization, including ventricular contraction
1.) A 2.) D 3.) F 4.) B 5.) G 6.) H
Rank from the first to the last steps to describe the correct order of events of a cardiac contractile cell action potential. Refer to the graph of a contractile cell action potential as you rank the events.
1.) Rapid depolarization phase: voltage-gated Na+ channels activate and Na+ enter, rapidly depolarizing the membrane 2.) Initial Repolarization phase: Na+ channels are inactivated and some K+ channels open; K+ leak out, causing a small initial depolarization 3.) Plateau phase: Ca2+ channels open and Ca2+ enters as K+ exit, prolonging the depolarization 4.) Repolarization phase: Na+ and Ca2+ channels close as K+ continue to exit, causing repolarization
Calculate the end-systolic volume (ESV) if the end-diastolic volume (EDV) in a resting heart is 110 ml and stroke volume (SV) is 70 ml.
40 ml
Approximately how much blood is pumped from each ventricle during the ventricular ejection phase?
70 ml
Calculate the stroke volume (SV) of a patient whose EDV is 140 milliliters and whose ESV is 60 milliliters.
80 milliliters - SV = EDV - ESV
What percentage of atria blood flows passively into the ventricles?
80%
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. Cardiac output increases to meet increased metabolic demand, often by increasing both heart rate and stroke volume at the same time. This occurs, for example, during maximal exercise, when cardiac output may increase to four or five times the resting level.
The main negative chronotropic effect on the heart is exerted by _____.
A -The vagus nerve's effect on the SA node slows down heart rate.
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
Which of the following chemical messengers decreases heart rate?
Acetylcholine
Which of the following terms refers to the force the ventricles must overcome to eject blood into their respective arteries?
Afterload
If Jerome is having an acute MI, which ECG change would you expect to see?
An elevated ST segment
What blood vessels do ventricles always pump blood into?
Arteries
Which of the following events is not part of the cardiac cycle? -Isovolumetric contraction phase -Atrial contraction phase -Ventricular filling phase -Isovolumetric relaxation phase
Atrial contraction phase
Which of the following hormones decrease cardiac output by decreasing blood volume and preload?
Atrial natriuretic peptide
What allows the atria and ventricles to depolarize and contract separately?
Atrioventricular (AV) node delay
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.
What might happen if the papillary muscles and/or chordae tendineae stopped functioning?
Blood would leak back into the atria from the ventricles.
What cardiac dysrhythmia does a patient have with a resting heart rate of 50 beats per minute?
Bradycardia
The ventricular ejection phase of the cardiac cycle is labeled _____.
C -During the ventricular ejection phase, the semilunar valves open and blood is ejected into the aorta and the pulmonary artery. The volume in the ventricles decreases from the end-diastolic volume to the end-systolic volume.
The parietal pericardium is labeled _____.
C -The parietal pericardium is the outer layer of the serous pericardium. It is fused to the inner surface of the fibrous pericardium.
Which of the following ion channels are time-gated closing channels?
Calcium ion channels
What condition results from excess fluid in the pericardial cavity compressing the heart and reducing the capacity of the ventricles to fill with blood?
Cardiac tamponade
What structure attaches the cusps of the atrioventricular valves to the papillary muscles?
Chordae Tendineae
Which coronary artery supplies the left atrium and parts of the left ventricle?
Circumflex artery
Which of the following events can be heard most easily with a stethoscope?
Closing of atrioventricular valves
Which of the following cell populations does not spontaneously generate action potentials in the cardiac conduction system?
Contractile cells
These activities change heart rate by changing the balance of parasympathetic and sympathetic stimulation of the heart. Sort each of the activities according to whether it decreases or increases heart rate.
Decrease- Lying Down,Digesting Increase- Standing Up, Fright or Anger, Exercise -The balance between parasympathetic and sympathetic stimulation to the heart controls heart rate. Increased parasympathetic activity decreases heart rate, and sympathetic activity increases heart rate.
What provides a graphic representation of all the action potentials occurring in the heart?
Electrocardiogram
The maximum amount of blood in the ventricles at the end of the ventricular filling phase is called __________.
End-diastolic Volume -At the end of atrial systole, each ventricle contains about 120 milliliters of blood, a volume known as the end-diastolic volume (EDV) because it is the ventricular volume at the end of ventricular diastole.
What are the three layers of the heart wall from superficial to deep?
Epicardium, myocardium, and endocardium
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
Which of the following blood vessels are associated with the coronary sinus?
Great cardiac
What kind of ion channels are unique to pacemaker cells?
HCN channels
Which of the following is appropriate for the box identified with a question mark?
Increased contractility -The positive inotropic effect of hormones and sympathetic stimulation cause increased contractility
Which of the following factors would increase cardiac output to the greatest extent?
Increased heart rate and increased stroke volume
Predict the changes in heart rate, stroke volume, and cardiac output for each of the following conditions by filling out the table below.Drag the appropriate labels to their respective targets.
Increased sympathetic activity: Increase HR, SV, CO Increase Preload: No change in HR, increase SV and CO Increased exercise: Increase HR, SV, CO Increase contractility: No change in HR, increase SV and CO
Which of the following statements best describes the apex of the heart?
Inferior tip of the heart and points toward the left side
Looking in a microscope, what are the visible structures that join cardiac muscle cells?
Intercalated discs
Which of the following structural components is only found in cardiac muscles?
Intercalated discs
During what phase is the S1 heart sound first heard?
Isovolumetric contraction phase
Which of the following statements describes the total refractory period of cardiac muscle?
It is longer than the total refractory period for skeletal muscle.
Which chamber generates the highest pressure during systole?
Left ventricle
Which of the following is not a risk factor for coronary artery disease or myocardial ischemia? -Low blood pressure -Male gender -Smoking -Older than age 50 for females
Low blood pressure
Which of the following is correct about the filling of the ventricles?
Most blood flows passively into the ventricles through open AV valves. -Yes, most of the ventricular filling is passive; atrial contraction adds just a little more blood.
Which type of treatment might Jerome receive once the MI is confirmed? Select all the correct answers. -Pain medication -IV of K+ -Nitroglycerin -Supplemental oxygen -IV of Na+ -IV of Ca++ -Muscle relaxant
Nitroglycerine, Supplemental Oxygen, and Pain medication
Baby A was scheduled for surgery to repair her atrial septal defect. The operation went well, and she is recovering nicely. Her mother wants to know whether she will need transfusions, since her blood pressure was so low before the surgery.Will she need transfusions to maintain her systemic volume?
No. Now that the shunt has been repaired, her blood is not being diverted from the systemic circuit into the pulmonary circuit, and her blood pressure should return to normal.
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 AV node will primarily affect the length of the __________.
P-R interval.
Which of the following structures is associated with the atria?
Pectinate muscles
During what part of the action potential will calcium ions enter the contractile cell?
Plateau phase
What is a contractile cell with a membrane potential of 0 mV experiencing?
Plateau phase
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 of the following blood vessels is not a great blood vessel of the heart?
Pulmonary arteries
Which vessel is guarded by a semilunar valve at its base?
Pulmonary trunk
Which of the following pacemaker cell populations has the slowest intrinsic rate of depolarization at about 20 times per minute?
Purkinje fiber system
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.
What obscures atrial repolarization on an electrocardiogram (ECG)?
QRS complex
Which wave on the electrocardiogram (ECG) represents ventricular depolarization?
QRS complex
Which electrocardiogram (ECG) finding can be used to measure heart rate?
R-R interval
What is initiated by a rapid influx of sodium ions into contractile cells creating a positive membrane potential inside the cell?
Rapid depolarization phase
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
Which of the following paths does an action potential in the heart normally take?
SA node atrial contractile cells AV node where it is delayed AV bundle right and left bundle branches Purkinje fibers ventricular contractile cells
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
The echocardiogram revealed an atrial septal defect as well as confirming the enlarged right ventricle and pulmonary trunk. Baby A's systemic blood pressure is also decreased.What is the most likely explanation?
Since blood is moving from her systemic circuit into her pulmonary circuit, the pulmonary circuit is distended and the systemic circuit is low on blood.
What is the volume of blood pumped out by one ventricle per heart beat?
Stroke volume (SV
What two values are needed to calculate cardiac output (CO) for a ventricle?
Stroke volume (SV) and heart rate (HR)
Systole and DiastoleMr. G has mitral regurgitation. How has this caused a systolic murmur? First of all, let's sort out what is happening during systole and diastole.
Systole: AV valves are closed, semilunar valves are open, ventricles are contacting, blood is flowing through semilunar valves, blood is leaving the heart diastole: AV valves are open, blood is flowing through the AV valves, ventricles are relaxed, semilunar valves are closed, blood is entering the heart.
What part of an electrocardiogram (ECG) represents ventricular repolarization?
T wave
The aortic valve opens at _____.
The aortic valve opens when the pressure in the ventricle rises above aortic pressure.
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.
Mr. G talks in short bursts with frequent breaths. He tells you he used to feel breathless when he was walking, but now he has been having more and more trouble breathing even when he is lying down at night. 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.
The cardiac chamber with the thickest wall is the __________.
The left ventricle has the thickest wall because it has to generate the most pressure.
Why would tricuspid stenosis cause a diastolic murmur?
The tricuspid valve is partly blocked, so when blood is flowing through it, there will be a noise of turbulent blood flow. Blood flows through the tricuspid during diastole, so that is when you hear the murmur.
What activity is occurring in the heart during the Q-T interval on an electrocardiogram (ECG)?
The ventricular cells are undergoing action potentials.
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.
Which of the following statements best describes how coronary artery anastomoses might help a patient with coronary artery disease?
They provide alternate routes of blood flow when a vessel is blocked
Atrial Natriuretic PeptideMr. G's online file also has the results of his recent blood tests. The only thing that looks abnormal is something called ANP − atrial natriuretic peptide. It is elevated. Why would this hormone be elevated in Mr. G, and what is it doing to him?
This hormone comes from the overstretched atrium and makes Mr. G lose more Na+ and water in his urine, lowering blood volume and reducing the load on the atrium.
Which of the following functions is not associated with the heart? -To help maintain homeostasis of blood pressure -To increase the rate at which erythrocytes are formed -To pump blood through two different sets of vessels, or circuits -To produce a hormone called atrial natriuretic peptide
To increase the rate at which erythrocytes are formed
Which cranial nerves have a negative chronotropic effect on heart rate?
Vagus nerves (CN X)
Which of the following cardiac dysrhythmias is immediately life-threatening and manifests on the electrocardiogram (ECG) with chaotic activity?
Ventricular fibrillation
According to the Frank-Starling law, a bigger preload will result in __________.
a stronger contraction -A bigger preload means increased stretch of the ventricular muscle cells and therefore, a stronger contraction.
What vessel delivers oxygenated blood to systemic capillaries for gas exchange?
aorta
Where does the left ventricle send blood?
aorta
The P wave on an electrocardiogram (ECG) represents the depolarization of cells in the ________
atria
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
The mitral valve is the clinical name for the ______________.
bicuspid valve
Autorhythmicity in the heart is a function of ________.
cardiac pacemaker cells
Autorhythmicity is the responsibility of:
cardiac pacemaker cells
The cusps of the atrioventricular valves attach to the papillary muscles via the __________.
chordae tendineae -The tendon-like chords called chordae tendineae ensure that the atrioventricular valves do not open into the atria.
An increase in sympathetic stimulation of the heart would increase stroke volume by increasing __________.
contractility
Inotropic agents affect __________.
contractility
Digoxin is a positive inotropic agent derived from the foxglove family of plants. Which of the following is an effect of digoxin?
decreased ESV -Increased contractility and SV would lead to a decrease in the ESV
How would a decrease in blood volume affect both stroke volume and cardiac output?
decreased stroke volume and no change in cardiac output. -Yes, a decreased blood volume would decrease the end diastolic volume, thus lowering the stroke volume. Although this would initially lead to a decrease in the cardiac output, heart rate would increase because of increased activity of the sympathetic nervous system in an effort to maintain cardiac output.
Hemorrhage would lead to a __________ preload and therefore __________ cardiac output.
decreased; decreased -Blood loss will diminish the venous return and therefore decrease the preload. A decreased preload would cause a decrease in the stroke volume and therefore a decrease in the CO.
The right side of the heart receives ________.
deoxygenated blood from the systemic circuit
The right side of the heart receives:
deoxygenated blood from the systemic circuit
Tricuspid StenosisMr. V has also had a recent echocardiogram and blood work. With tricuspid stenosis, what changes do you expect to see in the echocardiogram report?
dilated right atrium because blood is not flowing down into the right ventricle fast enough
What does the ECG wave tracing represent?
electrical activity in the heart
What largely determines preload?
end-diastolic volume (EDV)
The visceral pericardium is the same as the ________.
epicardium
The visceral pericardium is also known as the __________.
epicardium -The visceral pericardium, also known as the epicardium, is considered the most superficial layer of the heart wall.
Which of the following would increase heart rate?
epinephrine and norepinephrine -Yes, secreted by the adrenal medulla as a result of sympathetic stimulation, these hormones act as part of the sympathetic response, increasing heart rate.
When threshold is reached at the SA node (an autorhythmic cell), what channels open causing further depolarization of the membrane?
fast calcium
High-pressured blood in the ventricles ________.
forces the semilunar valves open
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 atriumThe right side of the heart is sending blood to the lungs. The lungs are low pressure, so the right side of the heart is also low pressure. The left side is high pressure.
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 heart is located _________.
in the mediastinum -The heart is situated slightly to the left side in the thoracic cavity in the mediastinum.
How would an increase in the sympathetic nervous system increase stroke volume?
increased contractility -Yes, an increase in sympathetic nervous system activity would increase contractility (by increasing available calcium), thus increasing stroke volume. Contractility causes an increase in stroke volume by decreasing end systolic volume; it does not change end diastolic volume.
By what mechanism would an increase in venous return increase stroke volume?
increased end diastolic volume. -Yes, an increase in venous return increases the end diastolic volume. The fibers are stretched more, resulting in an increase in the force of contraction (preload, or the Frank-Starling Mechanism).
Which of the following would increase cardiac output to the greatest extent?
increased heart rate and increased stroke volume. -Yes, cardiac output = heart rate x stroke volume.
The apex of the heart is __________.
inferior -The apex of the heart is the inferior tip of the heart and points toward the left side.
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 -The plateau phase of the cardiac action potential is due to the opening of calcium ions channels.
Ventricular systole begins during the __________ phase of the cardiac cycle.
isovolumetric contraction -During the isovolumetric contraction phase, ventricular systole and atrial diastole begin and the AV valves close.
Put the phases of the cardiac cycle in the correct order, starting after ventricular filling.
isovolumetric contraction, ventricular ejection, isovolumetric relaxation
How will the cardiac output change if you double the heart rate but reduce the stroke volume by one-half?
it will not change -The cardiac output will remain the same, because CO = HR × SV = 2HR × SV/2.
Blood returning from the lungs enters the __________.
left atrium -Oxygenated blood returning from the lungs via the pulmonary veins enters the left atrium.
Which heart chamber receives blood from the pulmonary veins?
left atrium -Yes, the left atrium receives oxygenated blood from the pulmonary veins.
The apex of the heart is situated toward the:
left hip
Which cardiac chamber has the thickest wall?
left ventricle
Which chamber pumps oxygenated blood out the aorta to the systemic circuit?
left ventricle -Yes, the left ventricle pumps oxygenated blood out the aorta to the entire body (systemic circuit).
The pulmonary circuit involves blood flow from the heart to and from the:
lungs
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 -Donating blood does not alter resting cardiac output. However, the decreased blood volume does decrease venous return and end diastolic volume. This decreases preload, thereby lowering stroke volume. By itself, decreased stroke volume would decrease cardiac output. But remember, the body still requires a resting blood flow of around 5 L/minL/min. To meet this demand, homeostatic mechanisms quickly restore cardiac output to resting levels. For example, heart rate is increased as parasympathetic influence is removed and sympathetic activity is increased. Even though your blood volume is a bit low, your body has no problem compensating to meet your resting metabolic needs. Running away from a tiger? Now that might be a different story.
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 aortic valve closes when __________.
pressure in the left ventricle falls below aortic pressure -The aortic valve closes to prevent backflow of blood into the ventricle.
The AV valves close when __________.
pressure in the ventricles increases -During the isovolumetric contraction phase, the pressure in the ventricles rises rapidly as the ventricles begin to contract. This high pressure closes the AV valves
What is the function of the valves in the heart?
prevent backflow of blood through the heart
The right side of the heart pumps deoxygenated blood into _____.
pulmonary arteries, which is B in the picture
Blood that leaves the right ventricle enters the __________.
pulmonary trunk -When the right ventricle contracts, blood passes through the pulmonary semilunar valve into the pulmonary trunk.
Which of the following vessels carries oxygenated blood?
pulmonary vein
Oxygenated blood is delivered to the left atrium through the ____________.
pulmonary veins
What vessel(s) deliver oxygenated blood to the left atrium?
pulmonary veins
What valve prevents the backflow of blood from the right ventricle into the right atrium?
right atrioventricular valve (tricuspid valve)
Which chamber receives blood from the superior and inferior vena cavae?
right atrium -Yes, the right atrium receives unoxygenated blood from the systemic circuit.
The area shaded in orange receives blood supply from the __________.
right coronary artery -The right coronary artery travels inferiorly and laterally along the right atrioventricular sulcus, where it gives off several branches that supply the right atrium and ventricle.
Which heart chamber pumps unoxygenated blood out the pulmonary trunk?
right ventricle -Yes, the right ventricle pumps unoxygenated blood out the pulmonary trunk to the lungs.
The right and left atria depolarize and contract following the arrival of the action potential from the __________.
sinoatrial (SA) node
What normally serves as the pacemaker of the entire heart?
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 vessels that deliver oxygen to the tissues of the body are part of the __________.
systemic circuit
Which of the following happens immediately after the P wave?
the atria contracts -After the atrial depolarization (P wave), the atria contract, allowing them to empty and causing the ventricles to reach their EDV.
Which of the following events will immediately follow the phase of the cardiac cycle depicted in the figure? -end-systolic volume (ESV)
the atrioventricular valves open -This is the isovolumetric relaxation phase. During the next phase, the ventricular filling phase, the ventricles are in diastole and atrial systole occurs.
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.
Blood in the right atrium should travel next past the ________.
tricuspid valve and into the right ventricle
The heart is actually (one, two, or three) pumps?
two pumps -Yes, the right side of the heart pumps to/from the lungs (pulmonary circuit) and the left side of the heart pumps to/from the rest of the body (the systemic circuit).
Both the left and right atria receive blood from ________.
veins
Both the left and right atria receive blood from:
veins
Blood from the systemic circuit returns to the heart via the __________.
venae cavae -The two veins that drain the majority of the systemic circuit are the superior and inferior venae cavae.
The chambers that have just emptied when the second heart sound is heard are the __________.
ventricles -The second heart sound is caused by the closing of the semilunar valves, which happens shortly after ventricular systole is over.
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
Repolarization of an autorhythmic cell is due to the opening of which channels?
voltage-gated potassium channels
