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Extra Credit Assignment for Cardiovascular System
This assignment is worth a maximum of two (2) points
on one of your lecture exams
** Answers to Cardiovascular System Extra Credit **
• On the diagram below, color the oxygen-rich blood red and the oxygen-poor blood blue. Label the
parts:
lung capillaries
pulmonary arteries
pulmonary veins
lt. atrium
lt. ventricle
rt. atrium
rt. ventricle
systemic veins
systemic arteries
systemic capillaries
Continued on the next page....
• Label the parts on the diagram below:
desmosome
sarcoplasmic
reticulum
gap junction
intercalated
disc (disk)
T-tubule
sarcomere
Study Questions on Anatomy Review: The Heart:
1. What's the difference between the blood in the right side of the heart and the left side of the heart?
Right side = deoxygenated; left side = oxygenated.
2. a. Where does the blood go that is pumped out of the right heart?
To the lungs
b. What happens to the blood in the lungs?
Blood becomes oxygenated (and loses carbon dioxide, CO2)
c. Where does the blood go that is pumped out of the left heart?
To the organs/tissues
3. What is the pulmonary circuit and the systemic circuit?
Pulmonary circuit brings blood to/from lungs; systemic circuit brings blood to/from other tissues
and organs
4. What three structural features are found on histological images of cardiac muscle?
Four features: striated, branched, mononucleated, intercalated discs
5. What are the names of the two types of cell junctions in cardiac muscle cells?
Gap junctions and desmosomes
6. What is the function of desmosomes?
Connects adjacent cells together firmly
7. What is the function of gap junctions?
Allows small molecules/ions to flow rapidly between cells
Continued on next page....
Intrinsic Conduction System
Graphics are used with permission of:
Pearson Education Inc., publishing as Benjamin Cummings (http://www.aw-bc.com)
Label the following graphic:
SA Node (pacemaker)
internodal fibers
AV node
AV bundle (of His)
right/left bundle branches
Purkinje fibers
Continued on next page...
• On the following diagram indicate where the following normally occur:
atrial depolarization, ventricular depolarization, ventricular repolarization, atrial repolarization
ventricular
depolarization
atrial
depolarization
ventricular
repolarization
Study Questions on the Intrinsic Conduction System:
1. What is the purpose of the intrinsic conduction system of the heart?
Sends signals for depolarization/repolarization to precisely regulate contraction of the myocardium so
the heart pumps as efficiently as possible
2. What type of cells are present in the intrinsic conduction system of the heart? Specialized myocardial
cells
3. List the six areas within the heart where autorhythmic cells are found.
SA node, AV node, AV bundle, bundle braches (rt/lt), purkinje fibers
4. Match the six areas within the heart where autorhythmic cells are found to their location within the heart.
Location Within the Heart:
6 - a. Interatrial septum to the interventricular
septum.
5 - b. Lower interventricular septum to the
myocardium of the ventricles.
2 - c. Inferior interatrial septum.
4 - d. Upper right atrium.
1 - e. Throughout the walls of the atria.
3 - f. Within the interventricular septum.
Continued on Next page...
Areas Where Autorhythmic Cells Are Found:
E;1. Internodal Pathway
C;2. AV Node
F;3. Bundle Branches
D;4. SA Node
B;5. Purkinje Fibers
A;6. AV Bundle
5. Match the six areas within the heart where autorhythmic cells are found to their function.
Functions:
Areas Where Autorhythmic Cells Are
4 - a. Initiates the depolarization impulse
Found:
that generates an action potential,
D;1. Internodal Pathway
setting the overall pace of the
C;2. AV Node
heartbeat.
F;3. Bundle Branches
5 - b. Convey the action potential to the
A;4. SA Node
contractile cells of the ventricle.
B;5. Purkinje Fibers
2 - c. Delays the action potential while
E;6. AV Bundle
the atria contract.
1 - d. Links the SA node to the AV node,
distributing the action potential to the
contractile cells of the atria.
6 - e. Electrically connects the atria and
the ventricles, connecting the AV
node to the Bundle Branches.
3 - f. Conveys the action potential down
the interventricular septum.
6. Explain the difference between the electrical and mechanical events which occur within the heart, and
explain the cell types that carry out each. Which occurs first, the electrical or mechanical events?
Electrical events occur first in specialized myocardial cells of the cardiac conduction system
Mechanical events occur second in myocardical cells
7. In an ECG tracing, how are the following represented:
a. atrial depolarization - P wave
b. atrial repolarization - atrial T-wave (or sometimes Ta wave) - not usually seen on ECG
c. ventricular depolarization - QRS complex (three different waves: Q, R, and S)
d. ventricular repolarization - T wave
8. Why is it important for the contraction of the ventricle to begin at the apex and move superiorly.
Helps to eject ventricular blood more efficiently
9. a. The P wave indicates the electrical event of atrial depolarization. What mechanical event follows the
P wave? Atrial contraction
b. The QRS complex indicates the electrical event of ventricular depolarization. What mechanical event
follows the QRS complex? Ventricular contraction
c. The T wave indicates the electrical event of ventricular repolarization. What mechanical event
follows the T wave ? Ventricular relaxation
The Cardiac Cycle
Graphics are used with permission of:
adam.com (http://www.adam.com/)
Benjamin Cummings Publishing Co (http://www.awl.com/bc)
Study Questions on the Cardiac Cycle:
1. What is a cardiac cycle?
Series of repeating events representing all of the events associated with blood
flow through the heart during one, complete heartbeat
2. What opens and closes the heart valves?
Changes in pressure on either side of the valves
3. List the three phases of the Cardiac Cycle. 1) Ventricular filling, 2) ventricular
systole, and 3) isovolumetric relaxation
4. Match the stages of the cardiac cycle to their description.
X - 1a. Ventricular Filling: Passive
v. Ventricles contract and
intraventricular pressure rises,
closing the AV valves.
Z - 1b. Ventricular Filling: Atrial
Contraction
w. Ventricles relax and ventricular
pressure drops. Blood backflows,
closing semilunar valves.
V - 2a. Ventricular Systole:
Isovolumetric Contraction
x. Blood flows passively into the atria,
through open AV valves, and into
the ventricles.
Y - 2b. Ventricular Systole: Ejection
y. Rising ventricular pressure forces
semilunar valves open. Blood is
ejected from the heart.
W - 3. Isovolumetric Relaxation
z. Atria contract, forcing the remaining
blood into the ventricles.
5. True or false: Blood passes through the bicuspid valve at the same time blood is also
passing through the tricuspid valve. True
6. What closes the AV valves? Pressure in the ventricles becomes higher than
pressure in the atria
7. What opens the semilunar valves? Pressure in the ventricles becomes higher than
the pressure holding the semilunar valves closed (afterload).
8. What closes the semilunar valves? Pressure in the ventricles becomes less than
the pressure in the blood vessels distal to the semilunar valves, i.e., the
pulmonary trunk and aorta.
9. What opens the AV valves? Pressure in the ventricles becomes lower than
pressure in the atria.
10. True or false: The right side of the heart contracts, then the left side of the heart
contract. False.
11. What is the relationship between pressure inside a chamber of the heart and the
state of the heart muscle (relaxed or contracted)?
Muscular contraction causes
high pressure; muscular relaxation results in lower pressure
12. Blood always moves from _HIGH___ pressure to _LOW_____ pressure.
13. What causes heart valves to open and close? Changes in pressure on either side
of the valves
14. Predict if the AV and semilunar valves are open or closed during the following
phases of the cardiac cycle by circling the appropriate answer on this chart:
State of AV Valves
Isovolumetric Contraction
Closed
State of Semilunar Valves
Closed
Isovolumetric Relaxation
Closed
Closed
Ventricular Ejection
Closed
Open
Ventricular Filling
Open
Closed
15. On the graph below, which letter corresponds to:
y - ventricular ejection
z- isovolumetric relaxation
w - ventricular filling
x - isovolumetric contraction
Continued on next page...
Cardiac Output
Graphics are used with permission of:
Pearson Education Inc., publishing as Benjamin Cummings (http://www.aw-bc.com)
Regulation of CO: HR
• Think about the effect increased sympathetic or parasympathetic input might have
on heart rate.
• Fill out this chart, making note of the reasons for the increase or decrease:
Effect on Heart Rate
Increased sympathetic stimulation
Increased HR = Increased CO
Increased parasympathetic stimulation
Decreased HR = Decreased CO
Regulation of CO: SV
• Think about the effect increased sympathetic or parasympathetic input or venous
return might have on stroke volume.
• Fill out this chart, making note of the reasons for the increase or decrease:
Effect on Stroke Volume
Increased sympathetic stimulation
Increased SV = Increased CO
Increased parasympathetic stimulation
No effect on SV = Unchanged CO
Increased venous return
Increased EDV (and EDP) = Increased SV
and thus increased CO
Study Questions on Cardiac Output:
1. Define cardiac output. Amount of blood pumped by each ventricle in one minute
2. What two factors does cardiac output depend on? Heart Rate and Stroke Volume
3. What is the mathematical relationship between cardiac output, heart rate, and stroke
volume. CO = HR x SV
4. Define heart rate. Number of times the heart beats each minute
5. What is the average heart rate in an adult at rest? About 75 beats/minute (bpm)
6. Define stroke volume. Volume of blood pumped by one ventricle with each beat
(contraction)
7. What is the average stroke volume in an adult at rest? About 70 ml/beat
8. Define end diastolic volume. The amount of blood that collects in a ventricle by
the end of its filling period, i.e., ventricular diastole
9. Define end systolic volume. The amount of blood left in a ventricle after its
contraction, i.e., ventricular systole
10. What is the mathematical relationship between end diastolic volume, end systolic
volume, and stroke volume? SV = EDV - ESV
**Think of EDV as being directly proportional to SV, and ESV being inversely
proportional to SV.
Therefore: If EDV goes up/down, SV goes up/down;
If ESV goes up/down, SV goes down/up. (Opposite)
11. If the ESV is 50 ml and the EDV is 120 ml, what is the stroke volume?
SV = 120 ml - 50 ml = 70 ml
12. If the heart rate is 75 beats per minute and the stroke volume is 70 ml per beat,
then what is the cardiac output?
CO = 75 beats/min x 70 ml/beat = 5,250 ml/min (or 5.25 L/min)
13. What's the relationship between venous return and stroke volume?
If venous return increases, stroke volume increases (Frank-Starling Law)
14. What is the effect of increased sympathetic activity on heart rate and stroke volume?
How does this effect cardiac output?
Sympathetic activity increases BOTH heart rate (HR) and stroke volume SV)
Therefore, sympathetic activity increases cardiac output
15. What is the effect of increased parasympathetic activity on heart rate and stroke
volume?
Parasympathetic activity decreases HR (but has no effect on SV).
Therefore, parasympathetic activity decreases HR.
16. What is the effect of a sudden loss of blood on heart rate and stroke volume?
1. Sudden loss of blood, e.g., hemorrhage, will decrease venous return to the heart.
2. Decreased venous return will result in a decreased EDV and, consequently, a decreased SV
3. Decreased SV will result in a decreased CO
4. In an effort to return CO to what it was prior to the blood loss, there is only one other parameter
the heart has to work with: HR
5. HR will, therefore, increase in an attempt to restore normal CO.