Blood in the heart chambers provides some nutrients to the heart muscle cells.
T
The role of the coronary arteries is to __________.
supply blood to the heart tissue
Which heart chamber sends deoxygenated blood to the lungs?
right ventricle
The left ventricular wall of the heart is thicker than the right wall in order to ________.
pump blood with greater pressure
Blood within the pulmonary veins returns to the ________.
left atrium
The condition where fluid compresses the heart and limits its ability to contract is called ________.
cardiac tamponade
The heart is actually (one, two, or three) pumps?
two pumps
Which chamber receives blood from the superior and inferior vena cavae?
right atrium
Which heart chamber receives blood from the pulmonary veins?
left atrium
Which heart chamber pumps unoxygenated blood out the pulmonary trunk?
right ventricle
Which chamber pumps oxygenated blood out the aorta to the systemic circuit?
left ventricle
Select the correct partial path below. This path is part of the complete blood flow pathway. You should be able to trace flow starting in any location.
Aorta to smaller systemic arteries to systemic capillaries to systemic veins to right atrium through the tricuspid valve
What separates the parietal and visceral pericardium?
pericardial cavity
Which of the following is a branch of the right coronary artery?
posterior interventricular artery
Which artery serves the myocardium of the lateral right side of the heart?
right marginal artery
From what vessel do the left and right coronary arteries arise?
aorta
Which of the following is the outermost covering of the heart?
fibrous pericardium
Which layer of the heart wall contracts and is composed primarily of cardiac muscle tissue?
myocardium
Which of the following is NOT a vein that returns blood to the right atrium of the heart?
pulmonary vein
Into what vessel does the left ventricle eject blood?
aorta
Into which chamber do the pulmonary veins send blood?
left atrium
Into which chamber of the heart do the superior vena cava, inferior vena cava, and coronary sinus return deoxygenated blood?
right atrium
Which chamber of the heart sends oxygenated blood to the aorta to the systemic circuit?
left ventricle
Which chamber of the heart receives oxygenated blood via the pulmonary circuit?
left atrium
The layers of the heart wall from superficial to deep are: __________.
epicardium, myocardium, and endocardium
The heart has __________ chambers and __________ valves.
four; four
Which of the following does NOT deliver blood to the right atrium?
pulmonary veins
Which of the following is NOT a difference between the left and right ventricles?
The left ventricle receives a smaller percentage of coronary blood supply than the right ventricle.
The __________ valve is located between the right atrium and the right ventricle.
tricuspid
Which of the following is NOT a difference between cardiac and skeletal muscle?
Cardiac muscle does not use the sliding filament mechanism for contraction; skeletal muscle does.
Cardiac tamponade results in ineffective pumping of blood by the heart because the excessive amount of fluid in the pericardial cavity will______.
prevent the heart from filling properly with blood
The greater the mass of tissue in an organ, the greater is its need for an adequate blood supply. Which chamber of the heart has the highest probability of being the site of a myocardial infarction?
left ventricle
The presence of an incompetent tricuspid valve would have the direct effect of causing ______.
reduced efficiency in the delivery of blood to the lungs
Which valve is located between the right atrium and ventricle?
tricuspid valve
A patient is prescribed a calcium channel blocker to prevent angina (chest pain) by decreasing the demand for oxygen. What is the explanation for this pharmacological effect?
A drug that inhibits the entry of calcium ions into the cytoplasm of cardiac cells decreases the force of myocardial contractility, thereby decreasing the oxygen demand, relieving the chest pain.
The source of blood carried to capillaries in the myocardium would be the ________.
coronary arteries
The fact that the left ventricle of the heart is thicker than the right ventricle reveals that it ________.
pumps blood against a greater resistance
If cardiac muscle is deprived of its normal blood supply, damage would primarily result from ________.
decreased delivery of oxygen
Which of the events below does not occur when the semilunar valves are open?
Ventricles are in diastole.
When viewing a dissected heart, it is easy to visually discern the right and left ventricles by ________.
noticing the thickness of the ventricle walls
Select the correct statement about the heart valves.
The AV valves are supported by chordae tendineae so that regurgitation of blood into the atria during ventricular contraction does not occur.
Select the correct statement about the structure of the heart wall.
The myocardium is the layer of the heart that actually contracts.
The term for pain associated with deficient blood delivery to the heart that may be caused by the transient spasm of coronary arteries is ________.
angina pectoris
The myocardium receives its blood supply from the coronary arteries.
T
The papillary muscles contract after the other ventricular muscles so that they can take up the slack on the chordae tendineae before the full force of ventricular contractions sends blood against the AV valve flaps.
F
Anastomoses among coronary arterial branches provide collateral routes for blood delivery to the heart muscle.
T
The left side of the heart pumps the same volume of blood as the right.
T
Arterial blood supply to heart muscle is continuous whether the heart is in systole or diastole.
F
Auricles slightly increase blood volume in the ventricles.
F
Which statement regarding cardiac muscle structure is accurate?
Myofibrils of cardiac muscle tissue vary in diameter and branch extensively.
Consider the following characteristics of the cells found in muscle tissue. Which feature is shared by both cardiac muscle and skeletal muscle?
striations
Which functional feature best describes the manner in which cardiac muscle contracts?
Automaticity (autorhythmicity) promotes the spontaneous contraction of the cardiac muscle cells.
The heart's pacemaker is the __________.
sinoatrial node
In an ischemic heart, the affected cardiac muscle cells are likely to have an altered ______.
resting membrane potential
What is the source of ATP for cardiac muscle contraction?
cellular respiration
What structures connect the individual heart muscle cells?
intercalated discs
Which of the following terms refers to a lack of oxygen supply to heart muscle cells?
ischemia
Compared to skeletal muscle, cardiac muscle ________.
has gap junctions that allow it to act as a functional syncytium
Cardiac muscle has more mitochondria and depends less on a continual supply of oxygen than does skeletal muscle.
F
Which part of the conduction system initiates the depolarizing impulse, which spreads throughout the heart?
SA node
What does the ECG wave tracing represent?
electrical activity in the heart
What does the QRS complex represent in the ECG wave tracing?
ventricular depolarization
Contraction of the atria results from which wave of depolarization on the ECG tracing?
P wave
Which part of the intrinsic conduction system delays the impulse briefly before it moves on to the ventricles?
AV node
Which of the following would increase cardiac output to the greatest extent?
increased heart rate and increased stroke volume
Which of the following would increase heart rate?
epinephrine and norepinephrine
How would an increase in the sympathetic nervous system increase stroke volume?
increased contractility
By what mechanism would an increase in venous return increase stroke volume?
increased end diastolic volume
How would a decrease in blood volume affect both stroke volume and cardiac output?
decreased stroke volume and no change in cardiac output
Isovolumetric relaxation and ventricular filling (two phases of the cardiac cycle) take place during __________.
ventricular diastole
Which of the following is correct about the filling of the ventricles?
Most blood flows passively into the ventricles through open AV valves.
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 causes the aortic semilunar valve to close?
greater pressure in the aorta than in the left ventricle
Put the phases of the cardiac cycle in the correct order, starting after ventricular filling.
isovolumetric contraction, ventricular ejection, isovolumetric relaxation
Increased pressure in the ventricles would close what valve(s)?
AV valves only
What is the main function of heart valves?
to prevent backward flow of blood
When the atria contract, which of the following is true?
The ventricles are in diastole.
Which of the following is equivalent to the ventricular volume during isovolumetric contraction?
The end diastolic volume (EDV)
Which of the following is true during ventricular systole?
The AV valves are closed.
During the ventricular ejection phase of the cardiac cycle, which of the following is true?
The semilunar valves are open.
Most of the decrease in ventricular volume takes place during which phase of the cardiac cycle?
ventricular ejection
Which of the following is equivalent to the ventricular volume during isovolumetric relaxation?
end systolic volume (ESV)
Most of the increase in left ventricular volume takes place during what phase of the cardiac cycle?
ventricular filling
In what direction does blood flow through the heart?
from a region of high pressure to a region of low pressure
Atrial pressure is greater than ventricular pressure during which phase of the cardiac cycle?
atrial contraction
At what point during the cardiac cycle does the AV valve close?
when ventricular pressure becomes greater than atrial pressure
At what point in the cardiac cycle does the semilunar valve open?
when ventricular pressure becomes greater than aortic pressure
Ventricular pressure is greater than aortic pressure during which phase of the cardiac cycle?
ventricular ejection
At what point in the cardiac cycle does the semilunar valve close?
when pressure in the ventricle becomes less than aortic pressure
Isovolumetric relaxation is characterized by which of the following?
The semilunar and AV valves are closed.
At what point in the cardiac cycle does the AV valve open?
when atrial pressure becomes greater than ventricular pressure
Action potentials generated by the autorhythmic cells spread to the contractile cells through what structures in the membrane?
gap junctions
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
When threshold is reached at the SA node (an autorhythmic cell), what channels open causing further depolarization of the membrane?
fast calcium
Repolarization of an autorhythmic cell is due to the opening of which channels?
voltage-gated potassium channels
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
At what rate does the sinoatrial (SA) node ensure depolarization in the heart?
75 beats of the heart per minute
Specifically, what part of the intrinsic conduction system stimulates the atrioventricular (AV) node to conduct impulses to the atrioventricular bundle?
sinoatrial (SA) node
Which of the following pacemaker cells generates impulses of approximately 75 depolarizations per minute in order to control the heart's contraction rate?
sinoatrial (SA) node
Which portion of the electrocardiogram represents the depolarization wave received from the sinoatrial (SA) node through the atria?
P wave
Which portion of the electrocardiogram represents the time during which the atria repolarize?
QRS complex
During which portion of the electrocardiogram do the atria contract?
P-R interval
What is the period during the cardiac cycle when the ventricles are completely closed chambers and blood volume in the chambers remains constant as the ventricles contract?
isovolumetric contraction phase
At what point in the cardiac cycle is pressure in the ventricles the highest (around 120 mm Hg)?
ventricular systole
How long is the cardiac cycle, assuming the heart beats 75 times per minute?
0.8 seconds
Which of the following would cause a decrease in the contractility of the heart?
increasing extracellular potassium levels
Calculate the stroke volume if the end diastolic volume (EDV) is 135 mL/beat and the end systolic volume (ESV) is 60 mL/beat.
75 mL/beat
Which of the following increases stroke volume?
exercise
A premature ventricular contraction is classified as a(n) __________.
extrasystole
The QRS complex on an electrocardiogram represents __________.
ventricular depolarization
The first heart sound (the "lub" of the "lub-dup") is caused by __________.
closure of the atrioventricular valves
Which of the following terms is correctly matched to its description?
quiescent period: total heart relaxation between heartbeats
In a healthy individual which of the following would be low?
Afterload
Which of the following would increase heart rate?
epinephrine
The left side of the heart is considered the systemic circuit pump.
T
The order of impulse conduction in the heart, from beginning to end, is __________.
SA node, AV node, bundle of His, bundle branches, and Purkinje fibers
When an ectopic pacemaker leads to an extrasystole, the ______.
ventricles contract before the atria contract
An abnormal P wave could be indicative of ______.
enlarged atria
Heart murmurs caused by a stenotic mitral valve ______.
are detected while blood flow into the left ventricle is reduced
Hypercalcemia could cause ______.
prolonged T wave
Which of the following cannot trigger tachycardia?
increased vagal tone
Which of the following structures sets the pace of heart contraction?
SA node
What does the T wave of the electrocardiogram (ECG) represent?
ventricular repolarization
Which of the following is NOT a factor that regulates stroke volume?
heart rate
What is afterload?
back pressure exerted by arterial blood
What causes heart sounds?
heart valve closure
A man enters the hospital complaining of chest pain. His history includes smoking, a stressful job, a diet heavy in saturated fats, lack of exercise, and high blood pressure. Although he is not suffering from a heart attack, his doctor explains to him that a heart attack is quite possible. What did the chest pain indicate? Why is this man a prime candidate for further complications?
Angina pectoris. If the coronary arteries are occluded (atherosclerosis), the heart muscle could be deprived of oxygen, resulting in a heart attack.
An older woman complains of shortness of breath and intermittent fainting spells. Her doctor runs various tests and finds that the AV node is not functioning properly. What is the suggested treatment?
Surgery to implant an artificial pacemaker
A patient was admitted to the hospital with chest pains. On admission, his pulse was 110 and blood pressure was 96/64. According to his history, his normal pulse rate is usually between 80 and 88 and his blood pressure runs from 120/70 to 130/80. Why did these changes in BP and HR occur?
To maintain the same cardiac output, the heart rate would need to increase to compensate for a decreased stroke volume.
A 55-year-old male was admitted to the hospital with heart failure. He complains of increasing shortness of breath on exertion, and of needing to sleep on three pillows at night. On physical assessment, the nurse determines that his ankles and feet are very swollen. Which of these symptoms either reflect left-sided and/or right-sided heart failure?
Left side failure results in shortness of breath. Right side failure results in edema in the extremities.
Asystole is the total absence of ventricular electrical activity. Would defibrillation be effective in this situation?
Defibrillation would not be effective: it interrupts chaotic electrical activity in the heart, and if there is no electrical activity, then there is nothing to interrupt.
Normal heart sounds are caused by which of the following events?
closure of the heart valves
To auscultate the aortic semilunar valve, you would place your stethoscope in the ________.
second intercostal space to the right of the sternum
Which of the following factors does not influence heart rate?
skin color
If the length of the absolute refractory period in cardiac muscle cells was the same as it is for skeletal muscle cells ________.
tetanic contractions might occur, which would stop the heart's pumping action
Norepinephrine acts on the heart by ________.
causing threshold to be reached more quickly
If the vagal nerves to the heart were cut, the result would be that ________.
the heart rate would increase by about 25 beats per minute
Which vessel(s) of the heart receive(s) blood during right ventricular systole?
pulmonary trunk
Which of these vessels receives blood during ventricular systole?
both the aorta and pulmonary trunk
Which of the following is not part of the conduction system of the heart?
AV valve
The tricuspid valve is closed ________.
when the ventricle is in systole
Select the correct statement about the function of myocardial cells.
The entire heart contracts as a unit or it does not contract at all.
During the period of ventricular filling ________.
blood flows mostly passively through the atria and the open AV valves into the ventricles
Hemorrhage with a large loss of blood causes ________.
a lowering of blood pressure due to change in cardiac output
The second heart sound is heard during which phase of the cardiac cycle?
isovolumetric relaxation
If we were able to artificially alter the membrane permeability of pacemaker cells so that sodium influx is more rapid, ________.
threshold is reached more quickly and heart rate would increase
Select the correct statement about cardiac output.
A slow heart rate increases end diastolic volume, stroke volume, and force of contraction.
During contraction of heart muscle cells ________.
some calcium enters the cell from the extracellular space and triggers the release of larger amounts of calcium from intracellular stores
Isovolumetric contraction ________.
refers to the short period during ventricular systole when the ventricles are completely closed chambers
Damage to the ________ is referred to as heart block.
AV node
The P wave of a normal electrocardiogram indicates ________.
atrial depolarization
The "lub" sounds of the heart are valuable in diagnosis because they provide information about the function of the heart's pulmonary and aortic valves.
F
Autonomic regulation of heart rate is via two reflex centers found in the pons.
F
An ECG provides direct information about valve function.
F
As pressure in the aorta rises due to atherosclerosis, more ventricular pressure is required to open the aortic valve.
T
Proxysmal atrial tachycardia is characterized by bursts of atrial contractions with little pause between them.
T
Congestive heart failure means that the pumping efficiency of the heart is depressed so that there is inadequate delivery of blood to body tissues.
T
Tissues damaged by myocardial infarction are replaced by connective tissue.
T
Chronic release of excess thyroxine can cause a sustained increase in heart rate and a weakened heart.
T
As part of a blood drive on campus for the American Red Cross, you and your friends have just donated 500 ml 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 ml 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
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
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.
Calculate the cardiac output if heart rate (HR) is 90 beats per minute, stroke volume (SV) is 110 ml/beat, end diastolic volume (EDV) is 140 ml, and end systolic volume (ESV) is 30 ml.
9.9 L/min
An increase in sympathetic stimulation of the heart would increase stroke volume by increasing __________.
contractility
Which part of the intrinsic conduction system normally initiates the depolarizing impulse that causes a heartbeat?
SA node
Which of these structures conduct(s) action potentials the slowest?
AV node