Chapter 18: The Heart Q&A
The P wave of a normal electrocardiogram indicates ________.
atrial depolarization
Which part of the intrinsic conduction system delays the impulse briefly before it moves on to the ventricles?
AV node
a lowering of blood pressure due to change in cardiac output
AV node
Which of the following is true during ventricular systole? The atria are in systole. The ventricles are empty. The AV valves are closed. The ventricles are relaxed.
The AV valves are closed.
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 ________ and ________ valves of the heart have no chordae tendineae attached.
aortic,pulmonary
Atrial pressure is greater than ventricular pressure during which phase of the cardiac cycle?
atrial contraction
Normal heart sounds are caused by which of the following events?
closure of the heart valves
The source of blood carried to capillaries in the myocardium would be the ________.
coronary arteries
The enlarged coronary vessel outside the heart that empties blood into the right atrium is the ________.
coronary sinus
In what direction does blood flow through the heart?
from a region of high pressure to a region of low pressure
What causes the aortic semilunar valve to close?
greater pressure in the aorta than in the left ventricle
Compared to skeletal muscle, cardiac muscle ________.
has gap junctions that allow it to act as a functional syncytium
What causes heart sounds?
heart valve closure
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
Which of the following would increase cardiac output to the greatest extent? decreased heart rate and increased stroke volume decreased heart rate and decreased stroke volume increased heart rate and decreased stroke volume increased heart rate and increased stroke volume
increased heart rate and increased stroke volume
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 infarction functional syncytium embolism
ischemia
Small muscle masses attached to the chordae tendineae are the ________.
papillary muscles
The left ventricular wall of the heart is thicker than the right wall in order to ________.
pump blood with greater pressure
The fact that the left ventricle of the heart is thicker than the right ventricle reveals that it ________.
pumps blood against a greater resistance
Which chamber receives blood from the superior and inferior vena cavae?
right atrium
Which heart chamber pumps unoxygenated blood out the pulmonary trunk?
right ventricle
Which heart chamber sends deoxygenated blood to the lungs?
right ventricle
The heart's pacemaker is the:
sinoatrial node
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
The role of the coronary arteries is to:
supply blood to the heart tissue
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
The heart is actually (one, two, or three) pumps?
two pumps
What does the QRS complex represent in the ECG wave tracing?
ventricular depolarization
The QRS complex on an electrocardiogram represents:
ventricular depolarization.
Isovolumetric relaxation and ventricular filling (two phases of the cardiac cycle) take place during __________.
ventricular diastole
Most of the decrease in ventricular volume takes place during which phase of the cardiac cycle?
ventricular ejection
Ventricular pressure is greater than aortic pressure during which phase of the cardiac cycle?
ventricular ejection
Most of the increase in left ventricular volume takes place during what phase of the cardiac cycle?
ventricular filling
At what point during the cardiac cycle does the AV valve close?
when ventricular pressure becomes greater than atrial pressure
What does the T wave of the electrocardiogram represent?
ventricular repolarization
At what point in the cardiac cycle does the AV valve open?
when atrial pressure becomes greater than ventricular pressure
At what point in the cardiac cycle does the semilunar valve close?
when pressure in the ventricle becomes less than aortic pressure
The tricuspid valve is closed ________.
when the ventricle is in systole
At what point in the cardiac cycle does the semilunar valve open?
when ventricular pressure becomes greater than aortic pressure
The heart has _____ chambers and _____ valves.
4; 4
Increased pressure in the ventricles would close what valve(s)?
AV valves only
In a healthy individual which of the following would be low?
Afterload
Which of the following is not a difference between cardiac and skeletal muscle? The plasma membranes of cardiac muscle cells interlock, but skeletal muscle fibers are independent. Cardiac muscle does not use the sliding filament mechanism for contraction; skeletal muscle does. Cardiac muscle cells quickly die in the absence of oxygen; skeletal muscle cells are better able to adapt to oxygen deficiency. Cardiac muscle cells contain more mitochondria than do skeletal muscle cells.
Cardiac muscle does not use the sliding filament mechanism for contraction; skeletal muscle does
Which of the following would increase heart rate? Epinephrine Low metabolic rate Parasympathetic stimulation Cold temperature
Epinephrine
Arterial blood supply to heart muscle is continuous whether the heart is in systole or diastole.
False
Cardiac muscle has more mitochondria and depends less on a continual supply of oxygen than does skeletal muscle.
False
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.
False
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.
False
Which of the following is correct about the filling of the ventricles? The majority of ventricular filling is caused by contraction of the atria. Most blood flows passively into the ventricles through open AV valves.
Most blood flows passively into the ventricles through open AV valves.
Contraction of the atria results from which wave of depolarization on the ECG tracing?
P wave
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 does not deliver blood to the right atrium? Inferior vena cava Superior vena cava Coronary sinus Pulmonary veins
Pulmonary veins
Which is correctly matched? Stroke volume: amount of blood pumped out by each ventricle in one minute Diastole: contraction period Quiescent period: total heart relaxation between heartbeats Systole: relaxed period
Quiescent period: total heart relaxation between heartbeats
Which of the following structures sets the pace of heart contraction? atrioventricular bundle AV node bundle branches SA node
SA node
Which part of the conduction system initiates the depolarizing impulse, which spreads throughout the heart?
SA node
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.
Select the correct statement about the heart valves. The mitral valve separates the right atrium from the right ventricle. Aortic and pulmonary valves control the flow of blood into the heart. The tricuspid valve divides the left atrium from the left ventricle. The AV valves are supported by chordae tendineae so that regurgitation of blood into the atria during ventricular contraction does not occur.
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 function of myocardial cells in a healthy, normally functioning heart. The refractory period in skeletal muscle is much longer than that in cardiac muscle. The atria, followed by the ventricles, contract as a unit or they do not contract at all. The influx of potassium ions from extracellular sources is the initiating event in cardiac muscle contraction. Each cardiac muscle cell is innervated by a sympathetic nerve ending so that the nervous system can increase heart rate.
The atria, followed by the ventricles, contract as a unit or they do not contract at all.
Which of the following is equivalent to the ventricular volume during isovolumetric contraction? the minimum ventricular volume (MVV) the stroke volume (SV) The end diastolic volume (EDV) the end systolic volume (ESV)
The end diastolic volume (EDV)
Which of the following is not a difference between the left and right ventricles? The walls of the left ventricle are thicker than the walls of the right ventricle. The left ventricle pumps blood to the systemic circuit, while the right ventricle pumps blood to the pulmonary circuit. The left ventricle receives a smaller percentage of coronary blood supply than the right ventricle. The left ventricle is a more powerful pump than the right ventricle.
The left ventricle receives a smaller percentage of coronary blood supply than the right ventricle.
Select the correct statement about the structure of the heart wall. Connective tissue in the heart wall aids in the conduction of the action potential. The heart chambers are lined by the endomysium. The myocardium is the layer of the heart that actually contracts. The fibrous skeleton forms the bulk of the heart.
The myocardium is the layer of the heart that actually contracts.
Isovolumetric relaxation is characterized by which of the following?
The semilunar and AV valves are closed.
During the ventricular ejection phase of the cardiac cycle, which of the following is true?
The semilunar valves are open.
When the atria contract, which of the following is true? The AV valves are closed. The ventricles are in diastole. The atria are in diastole. The semilunar valves are open.
The ventricles are in diastole.
Anastomoses among coronary arterial branches provide collateral routes for blood delivery to the heart muscle.
True
Chronic release of excess thyroxine can cause a sustained increase in heart rate and a weakened heart.
True
Congestive heart failure means that the pumping efficiency of the heart is depressed so that there is inadequate delivery of blood to body tissues.
True
The left side of the heart is considered the systemic circuit pump.
True
The left side of the heart pumps the same volume of blood as the right.
True
The myocardium receives its blood supply from the coronary arteries.
True
Tissues damaged by myocardial infarction are replaced by connective tissue.
True
Trabeculae carneae are found in the ventricles and never the atria.
True
Which of the events below does not occur when the semilunar valves are open? AV valves are closed. Ventricles are in systole. Blood enters pulmonary arteries and the aorta. Ventricles are in diastole.
Ventricles are in diastole.
Hemorrhage with a large loss of blood causes ________.
a lowering of blood pressure due to change in cardiac output
Which of the following is NOT a factor that regulates stroke volume? afterload preload contractility heart rate all the factors above regulate stroke volume
all the factors above regulate stroke volume
What is afterload?
back pressure exerted by arterial blood
During the period of ventricular filling ________.
blood flows passively through the atria and the open AV valves into the ventricles
What is the source of ATP for cardiac muscle contraction?
cellular respiration
The first heart sound (the 'lub' of 'lub-dup') is caused by:
closure of the atrioventricular valves.
If cardiac muscle is deprived of its normal blood supply, damage would primarily result from ________.
decreased delivery of oxygen
How would a decrease in blood volume affect both stroke volume and cardiac output?
decreased stroke volume and no change in cardiac output
What does the ECG wave tracing represent?
electrical activity in the heart
Which of the following is equivalent to the ventricular volume during isovolumetric relaxation? end diastolic volume (EDV) maximum ventricular volume (MVV) stroke volume (SV) end systolic volume (ESV)
end systolic volume (ESV)
The layers of the heart wall from superficial to deep are:
epicardium, myocardium, and endocardium.
Which of the following would increase heart rate? epinephrine and norepinephrine acetylcholine decreased activity of the sympathetic nervous system increased activity of the parasympathetic nervous system
epinephrine and norepinephrine
A premature ventricular contraction is classified as a(n):
extrasystole.
Put the phases of the cardiac cycle in the correct order, starting after ventricular filling. isovolumetric contraction, ventricular ejection, isovolumetric relaxation ventricular ejection, ventricular relaxation, isovolumetric contraction ventricular ejection, isovolumetric contraction, isovolumetric relaxation isovolumetric relaxation, ventricular ejection, isovolumetric contraction
isovolumetric contraction, ventricular ejection, isovolumetric relaxation
Blood within the pulmonary veins returns to the ________.
left atrium
Which heart chamber receives blood from the pulmonary veins?
left atrium
Which chamber pumps oxygenated blood out the aorta to the systemic circuit?
left ventricle
The time of day most hazardous for heart attacks is ________.
morning
When viewing a dissected heart, it is easy to visually discern the right and left ventricles by ________.
noticing the thickness of the ventricle walls
What is the main function of heart valves?
to prevent backward flow of blood
The ________ valve is located between the right atrium and the right ventricle.
tricuspid
The ________ valve of the heart has three flaps with chordae tendineae.
tricuspid
Which valve is located between the right atrium and ventricle?
tricuspid valve
