A&P CHAPTERS 18, 19 ,20 AND 21 ASSESSMENT UPDATED 2025 WITH
QUESTIONS AND 100% CORRECT ANSWERS //GRADED A+
Arrange these elements of the intrinsic conduction system in the order that a depolarizing impulse
travels during a normal heartbeat. VERIFIED ANSWER 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 VERIFIED ANSWER 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
Which part of the intrinsic conduction system normally initiates the depolarizing impulse that causes a
heartbeat?
A) SA node
B) AV bundle
C) AV node
,D) Internodal pathway VERIFIED ANSWER A) SA node
Which of these structures conduct(s) action potentials the slowest?
A) Bundle branches
B) AV bundle
C) AV node
D) Purkinje fibers VERIFIED ANSWER C) AV 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?
A) so the atria can finish contracting before the ventricles contract
B) so blood is forced upward, toward the semilunar valves
C) because the Purkinje fibers conduct action potentials away from the heart apex
D) because the AV bundle is the only electrical connection between the atria and the ventricles VERIFIED
ANSWER B) 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?
A) Action potentials are not delayed sufficiently at the AV node.
B) Action potentials propagate into the ventricles before the contractile cells have repolarized from the
previous heartbeat.
C) Purkinje fibers initiate spontaneous action potentials, which cause the ventricles to contract early.
D) Spontaneous action potentials in the SA node overlap such that the repolarizing phase of one action
potential cancels out the depolarizing phase of the next. VERIFIED ANSWER C) Purkinje fibers initiate
spontaneous action potentials, which cause the ventricles to contract early.
,The beginning of the QRS complex of the electrocardiogram (ECG) immediately precedes which of the
following events?
A) closing of the atrioventricular valves
B) atrial contraction
C) closing of the semilunar valves
D) blood ejection from the ventricles VERIFIED ANSWER A) closing of the atrioventricular valves
Which of the following can be heard with a stethoscope most easily?
A) Closing of atrioventricular valves
B) Contraction of atria
C) Blood flow into aorta
D) Isovolumetric contraction VERIFIED ANSWER A) Closing of atrioventricular valves
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
HINT: (HR * SV= CO)
A) 9.9 L/min
B) 14.0 L/min
C) 20.0 L/min
D) 34.0 L/min VERIFIED ANSWER A) 9.9 L/min
An increase in sympathetic stimulation of the heart would increase stroke volume by increasing
__________.
, A) end diastolic volume
B) heart rate
C) end systolic volume
D) contractility VERIFIED ANSWER D) contractility
Match the term in the left column to the blanks near their definition on the right.
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 VERIFIED ANSWER Match the term in
the left column to the blanks near their definition on the right.
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
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?
A) no change in cardiac output, decreased heart rate, increased stroke volume
B) decrease in cardiac output, decreased heart rate, decreased stroke volume
QUESTIONS AND 100% CORRECT ANSWERS //GRADED A+
Arrange these elements of the intrinsic conduction system in the order that a depolarizing impulse
travels during a normal heartbeat. VERIFIED ANSWER 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 VERIFIED ANSWER 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
Which part of the intrinsic conduction system normally initiates the depolarizing impulse that causes a
heartbeat?
A) SA node
B) AV bundle
C) AV node
,D) Internodal pathway VERIFIED ANSWER A) SA node
Which of these structures conduct(s) action potentials the slowest?
A) Bundle branches
B) AV bundle
C) AV node
D) Purkinje fibers VERIFIED ANSWER C) AV 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?
A) so the atria can finish contracting before the ventricles contract
B) so blood is forced upward, toward the semilunar valves
C) because the Purkinje fibers conduct action potentials away from the heart apex
D) because the AV bundle is the only electrical connection between the atria and the ventricles VERIFIED
ANSWER B) 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?
A) Action potentials are not delayed sufficiently at the AV node.
B) Action potentials propagate into the ventricles before the contractile cells have repolarized from the
previous heartbeat.
C) Purkinje fibers initiate spontaneous action potentials, which cause the ventricles to contract early.
D) Spontaneous action potentials in the SA node overlap such that the repolarizing phase of one action
potential cancels out the depolarizing phase of the next. VERIFIED ANSWER C) Purkinje fibers initiate
spontaneous action potentials, which cause the ventricles to contract early.
,The beginning of the QRS complex of the electrocardiogram (ECG) immediately precedes which of the
following events?
A) closing of the atrioventricular valves
B) atrial contraction
C) closing of the semilunar valves
D) blood ejection from the ventricles VERIFIED ANSWER A) closing of the atrioventricular valves
Which of the following can be heard with a stethoscope most easily?
A) Closing of atrioventricular valves
B) Contraction of atria
C) Blood flow into aorta
D) Isovolumetric contraction VERIFIED ANSWER A) Closing of atrioventricular valves
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
HINT: (HR * SV= CO)
A) 9.9 L/min
B) 14.0 L/min
C) 20.0 L/min
D) 34.0 L/min VERIFIED ANSWER A) 9.9 L/min
An increase in sympathetic stimulation of the heart would increase stroke volume by increasing
__________.
, A) end diastolic volume
B) heart rate
C) end systolic volume
D) contractility VERIFIED ANSWER D) contractility
Match the term in the left column to the blanks near their definition on the right.
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 VERIFIED ANSWER Match the term in
the left column to the blanks near their definition on the right.
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
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?
A) no change in cardiac output, decreased heart rate, increased stroke volume
B) decrease in cardiac output, decreased heart rate, decreased stroke volume
