Download Cardio Lab - LifeSciTRC

Jeannette Hafey
Chemistry/Biology Dept
Springfield College
Springfield, MA
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To show the interrelationships among stroke
volume, cardiac output and heart rate
To demonstrate the effect of an increase in
resistance on blood flow
To discuss the factors affecting the Ejection
Fraction
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To investigate the role of the heart as a pump
by the use of a model to simulate the action
of the heart
To study the relationship between heart rate,
stroke volume and cardiac output
To demonstrate the impact of the radius of
the blood vessel on the rate of blood flow and
as a determinant of blood pressure
To consider the effect of exercise on the End
Diastolic Volume and Ejection Fraction
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Procedure:
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Equipment:
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Adapted from “The Heart as a Pump: Cardiac
Mechanics Integrated with Anatomy for Introductory Human
A&P” by Daniel E. Lemons, Ph. D. ©2009 Science Learning
Workshop, Inc.
cardio model-
purchased from Denoyer-Geppert Science Co.
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Stroke Volume (SV) is the volume of blood
ejected by the ventricle in a single beat or
stroke.
SV is measured in milliliters or liters
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Cardiac Output or CO is the volume of
blood being pumped by the heart in one
minute
CO is measured in ml/minute or liters/minute
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Cardiac Output = Stroke volume x heart rate
ml/min
ml
beats/min
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1. If the average person’s heart rate is 72
beats per minute and the stroke volume is 70
ml, what is the approximate cardiac output of
the average person’s heart at rest?
A. 4950 ml/min
B. 7000 ml/min
C. 5040 ml/min
D. 142 ml/min
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2. During moderate exercise, such as
walking, Susan’s heart rate increased to 110
beats per minute and her stroke volume
increased to 100 ml. What is Susan’s CO
during moderate exercise?
A. 1100 ml/min
B. 2100 ml/min
C. 11,000 ml/min
D. 110,000 ml/min
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3. Appoximately _______ as much blood is
pumped per minute by the heart during
moderate exercise than at rest
A. 2 times
B. 3 times
C. 4 times
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4. Lance Armstrong’s resting heart rate is 34
beats per minute. If his resting cardiac
output is the same as the average person’s
CO, what is his stroke volume per cycle?
A. 70 ml
B. 100 ml
C. 128 ml
D. 148 ml
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5. What would be the explanation as to how
Lance Armstrong can achieve the same
cardiac output as the average person with a
heart rate of only 34 beats per minute
compared to the average person’s heart rate
of 72 beats per minute?
A.longer time between beats to fill with blood
B. greater force of contraction
C. stronger muscle in ventricular wall
D. more blood ejected per stroke
E. all of the above
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The following demonstration will utilize a
piece of equipment which will simulate the
work of the ventricle in pumping blood.
Measurements will be taken to determine
stroke volume and cardiac output when heart
rate is varied
The diaphragm functions as the
ventricle of the heart . Fluid
enters the pump via gravity
from the reservoir through
the inflow valve.
When the bulb is squeezed,
pressure is applied to the
outside of the diaphragm
forcing fluid out the outflow
valve into the metering tube.
The scale on the metering tube
is in 2 ml increments
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When the pump fills
with fluid and then
ejects it into the
metering tube, this
constitutes one
pumping cycle – PC
PC is comparable to
the cardiac cycle of
diastole/systole or
heart rate
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The volume of fluid
pumped with each
pumping cycle is
called the Cycle
Volume- CV
CV is comparable to
the stroke volume
(SV)
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The total amount of
fluid pumped in
one minute = Pump
Output or PO
PO is comparable to
cardiac output CO
in ml/min
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The following cases represent variations in
the frequency of pumps per minute in order
to determine the effect of pumping rate on
pump output
Purpose: to determine the most efficient rate
of pumping in order to maximize the output
Case #1: Measurement of cycle volume and pump output at
Pumping cycle rate of 10 cycles (beats) per minute
Timer: Pump every 6 seconds
Pumping Cycle
1
2
3
4
5
6
7
8
9
10
Meter Tube
Volume (ml)
CV (ml)
Average cycle volume (CV)= _________
Pump output (PO) in one minute = __________ ml at a rate of
10 cycles per minute (give total volume in cylinder)
Case #2: Measurement of cycle volume and pump output at
Pumping cycle rate of 30 cycles (beats) per minute
Empty the metering tube and close the reset valve
Time: Pump every 2 seconds
Pumping Cycle
1
2
3
4
5
6
7
8
9
10
Meter Tube Volume
(ml)
CV (ml)
Average cycle volume (CV)= _________
Pump output (PO)= __________ ml at a rate of 30 cycles per minute
Case #3: Measurement of cycle volume and pump output at
Pumping cycle rate of 60 cycles (beats) per minute
Empty the metering tube and close the reset valve
Time: One Pump every second
Pumping Cycle
1
2
3
4
5
6
7
8
9
10
Meter Tube Volume
(ml)
CV (ml)
Average cycle volume (CV)= _________
Pump output (P0)= __________ ml at a rate of 60 cycles per min
Case #4: Measurement of stroke volume and cardiac output when
Pumping as fast as the pumper can pump
Empty the metering tube and close the reset valve
Time: This is done for only 30 seconds
Record: Count the number of times pumped in 30 sec
Calculate: Pump Output volume for 60 seconds
30 sec
60 sec
#Pumps
PO = Meter Tube Volume (ml)
Average CV
Pumping rate in cycles per min ______
Average cycle volume (CV)= _________ PO/number of cycles
Pump Output (PO) = __________ ml/60 seconds
Table V. Comparing Cases 1-4
Case
1
2
PR (CPM)
PO(ml/min)
CV (ml)
6. Which case has the highest cycle
volume?
a. 1
b. 2
c. 3
d. 4
3
4
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7. Which case had the highest Pump Output?
a. 1
b. 2
c. 3
d. 4
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Graph results:
Cycle volume vs pumping rate
Pump output vs pumping rate
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From the graph of the results make a
statement about the results:
8. As the pumping rate increased, the cycle
volume ____________________________________
9. As the pumping rate increased, the pump
output ____________________________________
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10.Pump output increases as the pumping
rate increases
A. true
B. false
11. What would you say is the most efficient
pumping rate? ______________ cpm
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Questions for discussion:
1. How does heart rate affect cardiac output?
As the heart rate increases ______________
___________________________________________
2. What other factors could affect cardiac
output other than heart rate?
________________________________________
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3. During exercise, the heart rate does
increase, but, in comparison with the model,
the stroke volume (cycle volume) does not
decrease. This is important in maintaining
the blood flow to the tissues. What factor in
the living heart compensates so that, in spite
of a more rapid heart rate during exercise,
the stroke volume can also increase?
____________________________________________
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Formula:
Cardiac Output = stroke volume x heart rate
4. From the formula above, during exercise, what
factors change in order to increase cardiac
output so as to deliver more oxygen at a faster
pace to the muscles?
_____________________________________________
5. Which factor becomes more important with
more intense exercise? ________________________
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The purpose of this
demonstration is to
determine if the diameter of
the tubing has an effect on
the rate of flow through a
vessel
Setup: remove connection
to pump
1. Define – dilated blood vessel
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2. Define – constricted blood vessel
______________________________________________
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Remove tubing connecting reservoir to
inflow valve and connect tubing to a
“T” connector.
Outflow from connector enters tubing
with one outflow of 1/8” tubing and
the other of ¼” tubing. The length of
the tubing from each end of the
connector is 14” each and each allows
fluid to enter a 100 ml graduated
cylinder.
Close refill valve and fill metering tube
Place a shut-off valve on tubing
beneath reservoir, open refill valve
and fill reservoir so liquid enters tubing
When ready to begin, open shut-off
valve for 5 seconds and then close
Measure the volume of fluid in each
graduated cylinder
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Blood vessels constrict and dilate in
response to the needs of the body –
How does this affect flow rates?
Does this have an effect on the overall
blood pressure?
There will be three – 5 second trials with the average volume calculated
Diameter of
tubing
Volume – trial #1
Volume – trial #2
Volume – Trial #3
Average volume
1/8” tubing
¼” tubing
Calculate the rate of flow per minute :
ml/5 sec x 60 sec/min = ml/min
The flow rate per min for 1/8” tubing = ______ ml/min
The flow rate per min for ¼” tubing = _______ ml/min
The fastest flow occurred in the ________ tubing
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The flow of fluid through a tube is met with the
friction of the walls of the tube. The smaller the
diameter of the tube, the greater the friction and
thus, the greater the resistance to flow.
The arterioles have smaller diameters as well as
more control over their diameters than other
vessels and thus can offer the greatest resistance
to flow.
Assuming that the length of the tube and the
viscosity of the blood are constant
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Resistance = 1/radius4
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3. Which size tubing
offered greater resistance
to flow? ___________
R = 1/r4
Determine R for radius of
¼” _______
Determine R for radius of
1/8” _________
4. How many times
greater is the resistance
in the smaller tube than
the larger tube? ________
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5.How does the resistance affect the flow
rate?
A. greater R then faster flow
B. greater R then slower flow
6. The larger the radius of the
tube, the
A. greater the flow rate
B. slower the flow rate
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7.The greater the diameter or radius of a
vessel, the _____ the resistance
A. greater
B. lower
8. The smaller diameter tube, the _____ the
amount of friction against the walls of the
tube
A. greater
B. lower
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9.As the arterioles constrict, the resistance
A. increases
B. decreases
10. In order to increase flow to tissues, the
arterioles
A. dilate
B. constrict
The formula below shows the relationship among
Blood Pressure, resistance and flow
Pressure = Flow (CO in ml/min) x Resistance (1/r4)
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11. As the arteries constrict, resistance
a. increases
b. decreases
12. As the arteries constrict, therefore, blood
pressure
a. increases
b. decreases
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The End Filling Volume (EFV), like the End
Diastolic Volume, is the amount of fluid
in the diaphragm immediately before it is
compressed.
The End Ejection Volume (EEV) , like the
End Systolic Volume is the volume left
inside the diaphragm at the end of the
pumping stroke.
Filling
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It can be very difficult to determine the
value of EFV and EEV in either the model
heart or in the human heart because
there is no direct way to measure them.
These volumes can be very useful
clinically so indirect ways have been
developed to obtain them.
The fraction of the EFV that is pumped
out in one cycle is called the Ejection
Fraction (EF), and for the heart it is
calculated as follows:
EF = SV / EFV or SV/EDV
End Filling Volume
(EFV)
Ejection
End Ejection Volume
(EEV)
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EF = SV/EDV
Study this relationship:
1. As the stroke volume increases during
exercise (assume constant EDV), the EF
A. increase
B. decrease
2. Therefore during exercise the heart is
A. ejecting more of the end diastolic volume per
stroke
B. less of the end diastolic volume per stroke
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3. If Harold’s stroke volume is 72 ml at rest
and the End Diastolic Volume is 150 ml, then
calculate the Ejection fraction for Harold EF
= SV/EDV
At rest then, the % of the Harold’s EDV that is
ejected from the ventricle is about?
A. 25%
B. 50%
C. 75%
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4. Suggest a way that Harold’s heart could
increase the EF during exercise?
____________________________________________
5. During exercise, we would think that an
increase in the EF would be due to
A. greater filling of the heart
B. more forceful contraction of the heart
C. both of the above
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6. The EF tells us relatively speaking
a. how much of the blood filling the
ventricle is pumped out with each stroke
b. how much blood is left inside the
ventricle after a forceful contraction
c. both of the above
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7.How would you think that the EF of Lance
Armstrong’s heart would compare to the
average person’s heart?
A. higher
B. lower
C. the same
8.Discuss the reason for your answer
____________________________________________
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9. Assume that the EDV increases by 20%
during exercise to 180 ml and the SV
increases to 110 ml. What is the EF?
a. 45%
b. 61%
c. 25%
10. Thus the EF during exercise shows that
the heart
a. ejects more blood per stroke
b. ejects less blood per stroke
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11. Anna is a 59 year old woman with heart
failure. Her heart is enlarged and holds a
large volume of blood.
You would expect that her EF would be show
that
A. heart ejects a larger volume of blood with
each stroke
B. heart ejects a lower than normal volume of
blood with each stroke
C. EF would be normal for her age
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12. If Anna’s EDV is 200 ml with an EF of
25%, what is her stroke volume?
A. 100 ml
B. 75 ml
C. 150 ml
D. 50 ml
13. How much blood is left in her ventricle
after the contraction? ________ ml
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14. What is the major problem in Anna’s
heart to cause her to have an EF of only 25%?
____________________________________________
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15. With a resting heart rate of 100, Anna is
experiencing ___
A. tachycardia
B. bradycardia