AP Biology Lab 10: Physiology of the Circulatory
System
Driving Questions
How are heart rate and blood pressure affected by activity and temperature?
 What is the effect of changing body position on blood pressure and heart rate?
 How does heart rate change with exercise?
 What is the relationship between recovery rate and physical fitness?
 What is the relationship between heart rate and temperature in an ectothermic organism?
Background
The circulatory system consists of blood, blood vessels, and the heart. The heart is the muscular
pump that pushes blood through the blood vessels, delivering vital nutrients to the entire body. As
blood passes through the vessels, it exerts pressure, causing their walls to expand slightly. As blood
moves away from the heart through the arteries to smaller blood vessels, the pressure decreases. For
every contraction of the heart, the arteries expand and relax. Measuring these contractions can give
you a person’s heart rate – the number of times the heart contracts per minute. Heart rate is
measured in beats per minute (bpm).
Blood pressure is usually measured in the brachial artery in the upper arm using a
sphygmomanometer. Blood pressure has two main components: systolic and diastolic pressure.
Systolic pressure is the pressure in the brachial artery when the ventricles (the two lower chambers)
of the heart contract. Diastolic pressure is the pressure in the artery when the ventricles are relaxed.
Blood pressure is reported using these two measurements (expressed in mm Hg).
The circulatory systems of humans and other endotherms are relatively unaffected by changes in
environmental temperatures. The heart rate of ectotherms, however, is significantly affected by
external temperature. In this lab, you will be exploring the effects of temperature on the heart rate
of the water flea, Daphnia magna. Most biological reactions occur at faster rates as temperature
increases. This effect is greatest in ectotherms between 5 °C and 35 °C. The increased metabolic rate
observed in ectotherms within this temperature is expressed as a value called "Q10". Q10 is the ratio
of the metabolic rate of an organism at one temperature compared to the rate at a temperature 10 °C
lower. A Q10 of 3 indicates that the metabolic rate of the organisms triples with a 10 °C increase in
temperature.
The steps below are part of the Procedure for this lab activity. They are not in the right order. Determine the
proper order and write numbers in the circles that put the steps in the correct sequence.
Third, determine
the change in
heart rate and
blood pressure
that occurs when
your partner
moves from a
reclining to a
standing position.
Next, determine
the average heart
rate of your
partner in a
reclining position.
Finally, determine
the average heart
rate for your
partner after
exercising for a
period of time.
Determine the
average heart
rate of your
partner in a
standing position.
Determine how
changes in
temperature
affect the heart
rate of Daphnia
magna.
Procedure
After you complete a step (or answer a question), place a check mark in the box () next to that step.
Note: When you see the symbol "�" with a superscripted number following a step, refer to the numbered Tech Tips
listed in the Tech Tips appendix that corresponds to your PASCO data collection system. There you will find detailed
technical instructions for performing that step. Your teacher will provide you with a copy of the instructions for these
operations.
Part 1 – Measuring blood pressure
Set Up
1.  Designate one lab partner as #1 and the other as #2.
2.  Partner #1  sit in a chair with one shirt sleeve rolled up.
3.  Partner #2  clean the bell of the stethoscope with an alcohol swab before beginning. Wait a
few minutes for the alcohol to evaporate before using the stethoscope.
4.  Wrap the cuff of the sphygmomanometer around the upper arm of partner #1. The cuff
should fit snuggly but should not be overly tight.
5.  Place the stethoscope on the inside of partner #1's elbow, just below the bicep muscle.
Collect Data
6.  Inflate the cuff until the pressure is above 140 mm Hg. This will cut off blood flow below the
cuff. As you listen through the stethoscope you should not hear any sound at this point.
7.  Slowly release the pressure in the cuff while listening through the stethoscope. Blood will
again flow through the brachial artery below the cuff.
8.  When the pressure in the cuff reaches the systolic pressure you will hear a tapping sound in
the stethoscope.
9.  Note the pressure at this point as the systolic pressure and record in Table 10.7.
10.  Continue to deflate the cuff until the tapping noise stops.
11.  At the moment the tapping noise stops, note the pressure as the diastolic pressure and
record in Table 10.7.
12.  Measure your partner's systolic and diastolic pressure two more times and record in Table
10.7.
13.  Calculate your partner's average systolic and diastolic pressure and record in Table 10.7.
14. Repeat for both partners and record data in each table 10.7 provided.
Part 2 – Fitness tests
Determine the fitness level for partner #1 by conducting fitness tests 1 to 5, then, if time permits, repeat for
partner #2.
Fitness Test 1: Comparing systolic pressure (reclining versus standing)
Set Up
14.  Designate one lab partner as #1 and the other as #2.
15.  Partner #1  Recline (lay down) for at least 5 minutes.
Collect Data
16.  Partner #2  Determine partner #1's reclining systolic and diastolic pressures.
Partner 1: Reclining systolic pressure: ______mm Hg Reclining diastolic pressure: _______mm Hg
Partner 2: Reclining systolic pressure: ______mm Hg Reclining diastolic pressure: _______mm Hg
17.  Have your partner remain reclined for 2 more minutes. Then have them stand up and
immediately record their blood pressure.
Partner 1: Standing systolic pressure: ______mm Hg
Standing diastolic pressure: _______mm Hg
Partner 2: Standing systolic pressure: ______mm Hg
Standing diastolic pressure: _______mm Hg
18.  Determine the change in systolic pressure by subtracting the reclining measurement from
the standing measurement.
19.  Record the difference in Table 10.8.
20.  Using Table 10.1, assign the appropriate fitness points based on the change in systolic
pressure and record in Table 10.8.
Table 10.1: Change in systolic pressure from reclining to standing
Change (in mm Hg)
Fitness Points
Rise of 8 or more
3
Rise of 2 to 7
2
No rise
1
Fall of 2 to 5
0
Fall of 6 or more
–1
21.  Why do you think your blood pressure change when you stood up?
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Fitness Test 2: Standing heart rate
Set Up
22.  Start a new experiment on the data collection system.
�(1.2)
23.  Connect the Hand Grip Heart Rate Sensor to the data collection system. �(2.1)
24.  Display heart rate in a digits display. �(7.3.1)
25.  Have your partner grip the handles of the heart rate sensor and stand at ease for 2 minutes.
Collect Data
26.  Start data recording. �(6.2)
27.  Record your partner's heart rate in beats per minute.
28.  Record in Table 10.8.
29.  Assign fitness points based on Table 10.2 and record in Table 10.8. Continue recording data.
Table 10.2: Standing heart rate
Heart Rate
(beats/min)
Fitness
Points
60 to 70
3
71 to 80
3
81 to 90
2
91 to 100
1
101 to 110
1
111 to 120
0
121 to 130
0
131 to 140
–1
Fitness Test 3: Reclining heart rate
Set Up
30.  While still recording data and maintaining their grip on the heart rate sensor, have your
partner recline for 5 minutes.
Collect Data
31.  After 5 minutes, record your partner's resting heart rate in beats per minute. Make sure they
remain reclined until the next test.
32.  Assign fitness points based on Table 10.3 and record in the Table 10.8.
Table 10.3: Reclining heart rate
Heart Rate
(beats/min)
Fitness
Points
50 to 60
3
61 to 70
3
71 to 80
2
81 to 90
1
91 to 100
0
101 to 110
–1
Fitness Test 4: Baroreceptor reflex
Set Up
33.  While still recording data and maintaining their grip on the heart rate sensor, have your
partner stand up.
Collect Data
34.  Observe the change in your partner's heart rate as soon as he or she stands up. This is called
the baroreceptor reflex,
My partner's baroreceptor reflex is ________________. My baroreflex is:_____________
35.  Subtract the reclining heart rate (recorded in Fitness Test 2) from the baroreceptor reflex to
determine the heart rate increase upon standing.
36.  Record this difference in Table 10.8.
37.  Assign fitness points based on Table 10.4 and record in Table 10.8.
Table 10.4: Heart rate increase from reclining to standing
Reclining
Heart
(beats/min)
Fitness Points for Heart Rate Increase on Standing (# beats)
0 to 10
11 to 18
19 to 26
27 to 34
35 to 43
50 to 60
3
3
2
1
0
61 to 70
3
2
1
0
–1
71 to 80
3
2
0
–1
–2
81 to 90
2
1
–1
–2
–3
91 to 100
1
0
–2
–3
–3
101 to 110
0
–1
–3
–3
–3
38.  Explain the change in heart rate you observed in your partner.
________________________________________________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
Fitness Test 5: Endurance
Set Up
39.  Your partner will now complete a step test. While still maintaining their grip on the heart
rate sensor and recording data, your partner should climb up and down a step (with an
approximate height of 18 inches) 5 times, allowing three seconds for each step up/down.
Collect Data
40.  Immediately after the completion of this exercise, measure your partner's heart rate.
Heart rate immediately after exercise: ______________
41.  Observe the time it takes for your partner's heart rate to return to the standing heart rate,
the recovery heart rate.
42.  Record the recovery heart rate in Table 10.8.
43.  Stop data recording. �(6.2)
44.  Assign fitness points based on Table 10.5 and record in Table 10.8.
Table 10.5: Time required for return of heart rate to standing level after exercise
Time (seconds)
Fitness Points
0 to 30
4
31 to 60
3
61 to 90
2
91 to 120
1
121+
1
1 to 10 beats above
standing heart rate
0
11 to 30 beats above
standing heart rate
–1
45.  Subtract your partner's normal standing heart rate (recorded in Fitness Test 1) from his/her
heart rate immediately after exercise in Fitness Test 5 to obtain heart rate increase after
exercise.
46.  Record this data in Table 10.8.
Data Analysis
Table 10.7: Blood pressure data Partner 1
Measurement
1
2
3
Average
2
3
Average
Systolic
Diastolic
Table 10.7: Blood pressure data Partner 2
Measurement
Systolic
Diastolic
1
Table 10.8 Fitness data, Partner 1
Fitness Test
Measurement
Points
Change in systolic pressure
from reclining to standing
Standing heart rate
Reclining heart rate
Heart rate increase upon
standing)
Heart rate increase after
exercise
Time to return to standing
heart rate after exercise
TOTAL SCORE
Table 10.8 Fitness data, Partner 2
Fitness Test
Measurement
Change in systolic pressure
from reclining to standing
Standing heart rate
Reclining heart rate
Heart rate increase upon
standing)
Heart rate increase after
exercise
Time to return to standing
heart rate after exercise
TOTAL SCORE
Table 10.10: Relative cardiac fitness, Partner 1,
Total Score
Relative Cardiac Fitness
18 to 17
Excellent
16 to 14
Good
13 to 8
Fair
7 or less
Poor
Points
Table 10.10: Relative cardiac fitness, Partner 2,
Total Score
Relative Cardiac Fitness
18 to 17
Excellent
16 to 14
Good
13 to 8
Fair
7 or less
Poor
47.  Assign fitness points based on Table 10.6 and record in Table 10.8.
Table 10.6: Heart rate increase after exercise
Standing
Heart
(beats/min)
Fitness Points for Heart Rate Increase Immediately
after Exercise (# beats)
0 to 10
11 to 20
21 to 30
31 to 40
41+
60 to 70
3
3
2
1
0
71 to 80
3
2
1
0
–1
81 to 90
3
2
1
–1
–2
91 to 100
2
1
0
–2
–3
101 to 110
1
0
–1
–3
–3
111 to 120
1
–1
–2
–3
–3
121 to 130
0
–2
–3
–3
–3
131 to 140
0
–3
–3
–3
–3
Better Fitness Recovery Rate Data Table
Partner1
HR Pre Exercise:
HR Immediately at the end of exercise:
HR 30 seconds post exercise:
HR 60 seconds post – exercise:
HR 90 seconds post-exercise:
HR120 seconds post exercise:
HR 150 seconds post exercise:
HR 180 seconds post – exercise:
HR 210 seconds post-exercise:
HR 240 seconds post exercise:
HR 270 seconds post exercise:
HR 300 seconds post – exercise:
Partner 2
ASFA. Spring 2009.
Name:
Due: 6Mar09 -- 8Mar09
AP Lab 10: Physiology of the Cardio-Vascular System
Analysis Questions
1. How did changing from a standing to a reclining position affect heart rate? Explain
the results you observed.
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2. How did the heart rate change from reclining to standing? What is the baroreceptor
reflex? And how is the baroreceptor reflex related to change in heart rate? (Why does
heart rate normally increase upon standing?)
________________________________________________________________________________________
________________________________________________________________________________________
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see next page.
3. If the participant had exercised for double the amount of time, how might his or her
heart rate have changed?
________________________________________________________________________________________
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4. From the data you collected, how would you define an individual that is fit?
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See next page
Synthesis Questions
Use available resources to help you answer the following questions.
1. Why would a person with a high fitness rating need to exercise for longer periods of
time in order to achieve a target heart rate (c. 150 bpm) than a person with a lower fitness
rating?
________________________________________________________________________________________
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2. Why do some people feel faint when quickly standing after reclining?
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3. What is recovery rate? Why is recovery rate different for fit individuals versus
sedentary individuals? Explain your answer in terms of muscle activity, gas content of
the blood, and cardio-pulmonary efficiency.
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