A&P 2 chapter 18 (heart physiology)
What is the expected heart rate when a heart is removed from a living body? a.) the heart would immediately stop beating b.) 75 beats / minute c.) 50 beats / minute d.) 100 beats / minute
100 beats / minute
Calculate the stroke volume if the end diastolic volume (EDV) is 135 mL/beat and the end systolic volume (ESV) is 60 mL/beat. a.) 60 mL/beat b.) 75 mL/beat c.) 205 mL/beat d.) 8100 mL/beat
75 mL/beat
Select the correct statement about cardiac output. a.) If a semilunar valve were partially obstructed, the end systolic volume in the affected ventricle would be decreased. b.) A slow heart rate increases end diastolic volume, stroke volume, and force of contraction. c.) Decreased venous return will result in increased end diastolic volume. d.) Stroke volume increases if end diastolic volume decreases.
A slow heart rate increases end diastolic volume, stroke volume, and force of contraction.
Which of the following structures receives the depolarization wave from the atria and passes impulses onto the ventricles? a.) bundle branches b.) AV node c.) atrioventricular bundle d.) SA node
AV node
Which part of the intrinsic conduction system delays the impulse briefly before it moves on to the ventricles? a.) AV node b.) SA node c.) bundle branches d.) Purkinje fibers e.) AV bundle (bundle of His)
AV node
Trace the pathway of stimulation through the heart. Which of these pathways shows stimulation in the correct order? a.) subendocardial conducting network, interventricular septum, AV bundle, AV node. b.) AV bundle, subendocardial conducting network, interventricular septum, SA node. c.) SA node, interventricular septum, AV node, papillary muscles. d.) AV node, AV bundle, interventricular septum, subendocardial conducting network
AV node, AV bundle, interventricular septum, subendocardial conducting network
ncreased pressure in the ventricles would close what valve(s)? a.) semilunar valves only b.) AV valves only c.) both semilunar and AV valves
AV valves only
The anatomy of the intrinsic conduction system causes contraction of the ventricles to begin at the apex and move superiorly. Why is this important? a.) because the AV bundle is the only electrical connection between the atria and the ventricles b.) so blood is forced upward, toward the semilunar valves c.) because the Purkinje fibers conduct action potentials away from the heart apex d.) so the atria can finish contracting before the ventricles contract
Beginning contraction at the apex causes blood to be forced upward, through the semilunar valves, and into the aorta and pulmonary trunk. This makes ventricular ejection more efficient, much like squeezing a tube of toothpaste up from the bottom is more efficient at dispensing the toothpaste than is squeezing from the top.
Which of the following can be heard with a stethoscope most easily? a.) Isovolumetric contraction b.) Closing of atrioventricular valves c.) Blood flow into aorta d.) Contraction of atria
Closing of atrioventricular valves
Which of the following is correct about the filling of the ventricles? a.) The majority of ventricular filling is caused by contraction of the atria. b.) 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? a.) T wave b.) QRS complex c.) P wave
P wave
As your skeletal muscles contract during physical activity, more blood is returned to the heart. Which variable would be affected and what would be the outcome of this action? a.) Contractility would be increased, which would result in a larger cardiac output. b.) Afterload would increase, which would increase cardiac output. c.) Preload would be increased, which would result in a larger cardiac output. d.) End-systolic volume would be increased, which would increase cardiac output.
Preload would be increased, which would result in a larger cardiac output.
Describe the pressures in the atria and ventricles that would cause the opening of the AV valves. a.) Pressure in the atria would be greater than the pressure in the ventricles. b.) Pressures in the atria and ventricles would be equal. c.) Pressure in the ventricles would be greater than in the atria.
Pressure in the atria would be greater than the pressure in the ventricles.
Which part of the conduction system initiates the depolarizing impulse, which spreads throughout the heart? a.) AV node b.) SA node c.) Purkinje fibers d.) AV bundle (bundle of His)
SA node
Electrical impulses pass through the conduction system of the heart in the following sequence: a.) SA node, AV node, bundle of His, bundle branches, and Purkinje fibers b.) SA node, bundle of His, AV node, bundle branches, and Purkinje fibers c.) SA node, bundle branches, bundle of His, AV node, and Purkinje fibers d.) SA node, bundle branches, AV node, bundle of His, and Purkinje fibers
SA node, AV node, bundle of His, bundle branches, and Purkinje fibers
Which of the following is true during ventricular systole? a.) The ventricles are relaxed. b.) The atria are in systole. c.) The ventricles are empty. d.) The AV valves are closed.
The AV valves are closed.
Which portion of the electrocardiogram represents the wave-like change in charge in the positive direction received by the atria from the sinoatrial (SA) node?a.) S-T segment b.) QRS complex c.) T wave d.) P wave
The P wave represents the depolarization of the left and right atria and the beginning of atrial systole.
Which portion of the electrocardiogram represents the time during which the ventricles are in systole? a.) Q-T interval b.) T wave c.) P wave d.) QRS complex
The Q-T interval is the period from the beginning of ventricular depolarization through ventricular repolarization, during which the ventricles are in systole.
What would happen to the SA node if a chemical blocker was used to reduce transport of Na+ into the pacemaker cells? a.) The SA node would depolarize more slowly, reducing the heart rate. b.) There will be no change. c.) The SA node would depolarize more quickly, decreasing the heart rate. d.) The SA node would depolarize more quickly, increasing the heart rate. e.) The SA node would depolarize more slowly, increasing the heart rate.
The SA node would depolarize more slowly, reducing the heart rate. Diffusion of Na+ into the pacemaker cell causes a gradual depolarization of the cell membrane, called the pacemaker potential. If the rate of depolarization slows down, it will take longer for the membrane to reach threshold and trigger the next action potential, which will reduce heart rate.
Which of the following is equivalent to the ventricular volume during isovolumetric contraction? a.) the end systolic volume (ESV) b.) the stroke volume (SV) c.) The end diastolic volume (EDV) d.) the minimum ventricular volume (MVV)
The end diastolic volume (EDV)
Isovolumetric relaxation is characterized by which of the following? a.) Pressure in the ventricle exceeds pressure in the aorta. b.) The semilunar and AV valves are closed. c.) Pressure in the atrium exceeds pressure in the ventricle. d.) Blood flows backward through the heart from high to low pressure.
The semilunar and AV valves are closed.
The P wave on an electrocardiogram represents __________. a.) atrial depolarization b.) ventricular depolarization c.) ventricular repolarization d.) atrial repolarization
atrial depolarization
During the ventricular ejection phase of the cardiac cycle, which of the following is true? a.) The AV valves are open. b.) The ventricles are in diastole. c.) The atria are in systole. d.) The semilunar valves are open.
The semilunar valves are open.
Specifically, what part of the intrinsic conduction system stimulates the atrioventricular (AV) node to conduct impulses to the atrioventricular bundle? a.) subendocardial conducting network (Purkinje fibers) b.) sinoatrial (SA) node c.) bundle branches d.) interventricular septum
The sinoatrial node, by spontaneously depolarizing faster than the atrioventricular node, initiates heart contraction.
When the atria contract, which of the following is true? a.) The semilunar valves are open. b.) The ventricles are in diastole. c.) The AV valves are closed. d.) The atria are in diastole.
The ventricles are in diastole.
Suppose a patient develops a myocardial infarction that disables the sinoatrial node. Would the heart still pump blood to the aorta and the pulmonary trunk? a.) No, because there will be no contraction of the atria. b.) Yes, because the ventricles will depolarize on their own without nodal stimulation at a rate of 50 times per minute. c.) No, because there would be no more connection between the atrioventricular node and the bundle branches. d.) Yes, because the atrioventricular node will still stimulate ventricular systole.
Yes, because the atrioventricular node will still stimulate ventricular systole.
Hemorrhage with a large loss of blood causes ________. a.) a rise in blood pressure due to change in cardiac output b.) no change in blood pressure but a slower heart rate c.) a lowering of blood pressure due to change in cardiac output d.) no change in blood pressure but a change in respiration
a lowering of blood pressure due to change in cardiac output
Atrial pressure is greater than ventricular pressure during which phase of the cardiac cycle? a.) isovolumetric contraction b.) ventricular ejection c.) atrial contraction d.) isovolumetric relaxation
atrial contraction
During the isovolumetric relaxation phase of the cardiac cycle, _______. a.) atrioventricular, aortic, and pulmonary valves are open b.) atrioventricular valves are closed; aortic and pulmonary valves are open c.) atrioventricular, aortic, and pulmonary valves are closed d.) atrioventricular valves are open; aortic and pulmonary valves are closed
atrioventricular, aortic, and pulmonary valves are closed
What best describes afterload? a.) degree of stretch of the heart muscle b.) contractility of cardiac muscle c.) cardiac reserve d.) back pressure exerted by arterial blood
back pressure exerted by arterial blood
During the period of ventricular filling, ________. a.) blood flows mostly passively from the atria through the atrioventricular (AV) valves into the ventricles b.) the aortic and pulmonary semilunar valves are open c.) the atria remain in diastole d.) pressure in the heart is at its peak
blood flows mostly passively from the atria through the atrioventricular (AV) valves into the ventricles
Which of the following receive(s) blood during ventricular systole? a.) aorta only b.) pulmonary arteries only c.) pulmonary veins only d.) both the aorta and pulmonary trunk
both the aorta and pulmonary trunk
Norepinephrine acts on the heart by ________. a.) decreasing heart contractility b.) blocking the action of calcium c.) causing threshold to be reached more quickly d.) causing a decrease in stroke volume
causing threshold to be reached more quickly
The beginning of the QRS complex of the electrocardiogram (ECG) immediately precedes which of the following events? a.) closing of the semilunar valves b.) atrial contraction c.) closing of the atrioventricular valves d.) blood ejection from the ventricles
closing of the atrioventricular valves
The first heart sound (the "lub" of the "lub-dup") is caused by __________. a.) closure of the semilunar valves b.) atrial contraction c.) closure of the atrioventricular valves d.) ventricular contraction
closure of the atrioventricular valves
Which of the following would cause a DECREASE in cardiac output (CO)? a.) suddenly standing up from a supine position b.) heightened use of skeletal muscle c.) decreasing thyroid function (thyroxine) d.) an increase in adrenal medulla output (epinephrine)
decreasing thyroid function (thyroxine)
What does the ECG wave tracing represent? a.) contraction of the heart b.) electrical activity in the heart
electrical activity in the heart
Which of the following is equivalent to the ventricular volume during isovolumetric relaxation? a.) end diastolic volume (EDV) b.) maximum ventricular volume (MVV) c.) stroke volume (SV) d.) end systolic volume (ESV)
end systolic volume (ESV)
Which of the following would increase cardiac output? a.) decreased cytoplasmic calcium concentration during contraction b.) epinephrine c.) parasympathetic stimulation d.) high blood pressure
epinephrine
Which of the following INCREASES stroke volume?a.) exercise b.) severe blood loss c.) decrease in end diastolic volume (EDV) d.) decrease in preload
exercise
Which of these is a condition marked by premature ventricular contraction? a.) extrasystole b.) ectopic focus c.) arrhythmia d.) heart block
extrasystole
The role of the chordae tendineae is to open the AV valves at the appropriate time. a.) True b.) False
false. Chordae tendineae anchor the cusps of the AV valves to the papillary muscles protruding from the ventricular walls. The chordae tendineae and the papillary muscles act as tethers that anchor the valve cusps in their closed position. I
Increasing end-diastolic volume (EDV) or end-systolic volume (ESV) will increase stroke volume. a.) True b.) False
false. Stroke volume (the volume of blood ejected from the ventricle during systole) is equal to the difference between EDV (the volume of blood in the ventricle before it contracts) and ESV (the volume of blood remaining in the ventricle after it contracts). Increasing EDV will result in a larger stroke volume; however, increasing ESV will result in a smaller stroke volume.
In what direction does blood flow through the heart? a.) from a region of high volume to a region of low volume b.) from a region of high pressure to a region of low pressure c.) from a region of high oxygen content to a region of low oxygen content d.) from ventricles to atria
from a region of high pressure to a region of low pressure
Which is most responsible for the synchronized contraction of cardiac muscle tissue? a.) small motor units b.) desmosomes c.) branching cells d.) gap junctions
gap junctions
What causes the aortic semilunar valve to close? a.) greater pressure in the aorta than in the left ventricle b.) equal ventricular and aortic pressures c.) higher ventricular pressure than aortic pressure
greater pressure in the aorta than in the left ventricle
What causes heart sounds? a.) heart valve closure b.) blood flowing from the atria into the ventricles c.) pressure of blood in the ventricles d.) opening of heart valves
heart valve closure
The Frank-Starling Law states that, if other factors are constant, a ________. a.) higher stroke volume will produce a higher end diastolic volume b.) higher stroke volume will produce a lower end diastolic volume c.) higher end diastolic volume will produce a higher stroke volume d.) higher end diastolic volume will produce a lower stroke volume
higher end diastolic volume will produce a higher stroke volume
Which of the following would decrease stroke volume? a.) increasing sympathetic stimulation b.) increasing contractility c.) increasing afterload d.) increasing preload
increasing afterload
The plateau phase of an action potential in cardiac muscle cells is due to the ________. a.) efflux of K+ through K+ channels b.) influx of Ca2+ through slow Ca2+ channels c.) influx of Na+ through fast Na+ channels d.) efflux of Ca2+ through fast Ca2+ channels
influx of Ca2+ through slow Ca2+ channels
What is the period during the cardiac cycle when the valves leading to and from the ventricles are completely closed and blood volume in the ventricles remains constant as the walls contract? a.) isovolumetric relaxation phase b.) isovolumetric contraction phase c.) ventricular ejection d.) ventricular filling
isovolumetric contraction phase
Put the phases of the cardiac cycle in the correct order, starting after ventricular filling. a.) ventricular ejection, ventricular relaxation, isovolumetric contraction b.) isovolumetric contraction, ventricular ejection, isovolumetric relaxation c.) isovolumetric relaxation, ventricular ejection, isovolumetric contraction d.) ventricular ejection, isovolumetric contraction, isovolumetric relaxation
isovolumetric contraction, ventricular ejection, isovolumetric relaxation
Which chambers of the heart contain oxygenated blood? a.) right and left ventricles b.) right and left atria c.) right atrium and ventricle d.) left atrium and ventricle
left atrium and ventricle
If the SA node is not functioning, an ECG will show ________. a.) more P waves than QRS waves b.) higher P waves c.) no P waves with a HR between 40-60 bpm d.) no QRS waves
no P waves with a HR between 40-60 bpm
Exercise results in skeletal muscles compressing veins which encourages blood to return to the heart. In this scenario, which of the following is correct? a.) end diastolic volume (EDV) decreases b.) venous return decreases c.) stroke volume decreases d.) preload increases
preload increases
Which of the following terms is correctly matched to its description? a.) quiescent period: period of total heart relaxation b.) stroke volume: amount of blood pumped out by each ventricle in one minute c.) ventricular diastole: period of ventricular contraction d.) atrial systole: period of atrial relaxation
quiescent period: period of total heart relaxation
Isovolumetric contraction ________. a.) occurs only in people with heart valve defects b.) refers to the short period during ventricular systole when the ventricles are completely closed chambers c.) occurs while the atrioventricular (AV) valves are open d.) occurs immediately after the aortic and pulmonary semilunar valves close
refers to the short period during ventricular systole when the ventricles are completely closed chambers
If the length of the absolute refractory period in cardiac muscle cells was the same as it is for skeletal muscle cells, ________. a.) pacemaker cells would cease to spontaneously depolarize b.) it would be much longer before cardiac cells could respond to a second stimulation c.) tetanic contractions might occur, which would stop the heart's pumping action d.) contractions would last as long as the refractory period
tetanic contractions might occur, which would stop the heart's pumping action
If the vagal nerves to the heart were cut, the result would be that ________. a.) the heart rate would increase by about 25 beats per minute b.) the atrioventricular (AV) node would become the pacemaker of the heart c.) parasympathetic stimulation would increase, causing a decrease in heart rate d.) the heart would stop, since the vagal nerves trigger the heart to contract
the heart rate would increase by about 25 beats per minute
What is the main function of heart valves? a.) to separate the left and right atria b.) to prevent backward flow of blood c.) to pump blood through the heart d.) to separate the atria and ventricles
to prevent backward flow of blood
As pressure in the aorta rises due to atherosclerosis, more ventricular pressure is required to open the aortic valve. a.) True b.) False
true
As soon as ventricular pressure falls below atrial pressure, the atrioventricular valve will open and ventricular filling will begin. a.) True b.) False
true
If blood volume decreased dramatically due to massive bleeding, the autonomic nervous system will attempt to maintain cardiac output by increasing the heart rate. a.) True b.) False
true
When released in large quantities, thyroxine, a thyroid gland hormone, causes a sustained increase in heart rate. a.) True b.) False
true
What does the QRS complex represent in the ECG wave tracing? a.) ventricular repolarization b.) ventricular depolarization c.) atrial depolarization d.) atrial repolarization
ventricular depolarization
What does the QRS wave of the electrocardiogram (ECG) represent? a.) atrial depolarizaton b.) ventricular repolarization c.) atrial repolarization d.) ventricular depolarization
ventricular depolarization
Isovolumetric relaxation and ventricular filling (two phases of the cardiac cycle) take place during __________. a.) ventricular systole b.) ventricular diastole
ventricular diastole
Most of the decrease in ventricular volume takes place during which phase of the cardiac cycle? a.) ventricular ejection b.) ventricular filling c.) atrial contraction d.) isovolumetric relaxation
ventricular ejection
Ventricular pressure is greater than aortic pressure during which phase of the cardiac cycle? a.) isovolumetric relaxation b.) isovolumetric contraction c.) ventricular filling d.) ventricular ejection
ventricular ejection
Most of the increase in left ventricular volume takes place during what phase of the cardiac cycle? a.) atrial contraction b.) isovolumetric relaxation c.) ventricular filling d.) ventricular ejection
ventricular filling
At what point in the cardiac cycle is pressure in the ventricles the highest (around 120 mm Hg in the left ventricle)? a.) ventricular filling b.) mid-to-late diastole (atrial contraction) c.) ventricular systole d.) early diastole (isovolumetric relaxation)
ventricular systole
At what point in the cardiac cycle does the AV valve open? a.) when the semilunar valve closes b.) when aortic pressure becomes greater than ventricular pressure c.) when atrial pressure becomes greater than ventricular pressure d.) when ventricular pressure becomes greater than aortic pressure
when atrial pressure becomes greater than ventricular pressure
At what point in the cardiac cycle does the semilunar valve close? a.) when ventricular pressure becomes greater than atrial pressure b.) when ventricular pressure becomes greater than aortic pressure c.) when pressure in the ventricle becomes less than aortic pressure d.) when atrial pressure becomes greater than ventricular pressure
when pressure in the ventricle becomes less than aortic pressure
The atrioventricular (AV) valves are closed ________. a.) when the ventricles are in systole b.) while the atria are contracting c.) when the ventricles are in diastole d.) by the movement of blood from atria to ventricles
when the ventricles are in systole
At what point in the cardiac cycle does the semilunar valve open? a.) when atrial pressure becomes greater than ventricular pressure b.) when ventricular pressure becomes greater than atrial pressure c.) when the AV valve closes d.) when ventricular pressure becomes greater than aortic pressure
when ventricular pressure becomes greater than aortic pressure
At what point during the cardiac cycle does the AV valve close? a.) when ventricular pressure becomes greater than aortic pressure b.) when aortic pressure becomes greater than ventricular pressure c.) when ventricular pressure becomes greater than atrial pressure d.) when the semilunar valve opens
when ventricular pressure becomes greater than atrial pressure
