Physiology of the Circulatory System - â€” Get a

TEACHER’S MANUAL WITH STUDENT GUIDE

LABORATORY

Physiology of the

CirculatorySystem

10

74-6580 8-Station Kit74-6581 1-Station Kit

©2007 Carolina Biological Supply Company Printed in USA

The materials and activities in this kit meet the guidelines and academic standards of the Advanced Placement(AP®) Program® and have been prepared by Carolina Biological Supply Company, which bears soleresponsibility for kit contents. Permission is granted to reproduce the Student Guide blackline masters at theend of this manual for use with the materials provided in the accompanying CarolinaTM AP® Biology kit orreplacement set.

For complete listings of CarolinaTM AP® Science materials, including the Advanced Placement® BiologyLaboratory Manual for Teachers (RN-74-6681) and the Advanced Placement® Biology Laboratory Manual forStudents (RN-72-6682), log on to www.carolina.com/ or refer to the current CarolinaTM Science catalog or thecurrent CarolinaTM Biotechnology & AP® Biology catalog.

Advanced Placement Program and AP are registered trademarks of the College Entrance Examination Board.

Property Measured Unit Symbol Description

Length *meter m 100 cm = 102 cm

centimeter cm 0.01 m = 10–2 m

millimeter mm 0.001 m = 10–3 m

micrometer μm 10–6 m = 10–3 mm

nanometer nm 10–9 m = 10–3 μm

Mass *kilogram kg 1000 g

gram g 1000 mg

milligram mg 0.001 g = 10–3 g

microgram μg 10–6 g

Amount of Substance *mole mol 6.02 x 1023 particles (atoms, ions, or molecules)

Concentration of a Solution mass percentage % Mass % = mass of solute/total mass of soln. × 100

parts per million ppm ppm of solute = mass of solute/total mass of soln. × 106

or 1 ppm = 1 mg solute/L soln.

molarity M Molarity = moles solute/L soln.

Volume (gases and liquids) kiloliter kL 1000 L

liter L 1000 mL = 1 dm3 = 10–3 m3

milliliter mL mL = cm3 = 10–3 L

microliter μL 10–6 L = 10–3 mL

Temperature (thermodynamic) *kelvin K K = °C + 273

Temperature (common) Celsius °C 0°K = –273°C

Force newton N kg•m/s2

Heat or Energy joule J N•m

**calorie cal 4.184 J

**Calorie (food) Cal 1000 calories = 1 kcal

Time *second s 60 s = 1 min

millisecond ms 10–3 s

Pressure pascal Pa N/m2 = kg/m•s2

**atmosphere atm 101,325 Pa = 101.325 kPa = 760 torr = 14.7 lb/in2

Bar bar 105 Pa

**Torr torr mm Hg = 133.3 Pa

* SI Base Unit

**Non-metric

Units of Measure Useful in AP® Biology

C a r o l i n a TM A P® T e c h S u p p o r t : 8 0 0 . 2 2 7 . 1 1 5 0 e x t 4 3 0 4 a n d e x t 4 3 8 1 T e a c h e r ’ s M a n u a l 3

This lab consists of three parts. In Activity A (Measuring Blood Pressure),students use a sphygmomanometer and stethoscope to measure blood pressure.In Activity B (Testing Physical Fitness), students count pulse rates underdifferent conditions to determine their level of physical fitness. In Activity C(Heart Rate of Daphnia), students observe the heart rate of Daphnia atdifferent temperatures.

• Use a sphygmomanometer and stethoscope to measure systolic anddiastolic blood pressure

• Observe the response of the human circulatory system to various factorsand use the results to determine the subject’s level of physical fitness

• Investigate the relationship of temperature and heart rate for anectotherm

This kit is appropriate for Advanced Placement® high school students andaddresses the following National Science Education Standards:

Unifying Concepts and Processes• Systems, order, and organization

• Evidence, models, and explanation

• Constancy, change, and measurement

Science as Inquiry• Abilities necessary to do scientific inquiry

• Understanding about scientific inquiry

Life Science• Matter, energy, and organization in living systems

Activity A: 30–40 minutes

Activity B: 40 minutes

Activity C: 30–40 minutes

Note that times given above encompass lab activity time only. Time needed tocomplete the Analysis of Results sections is not included.

• Use this kit only in accordance with prudent laboratory safetyprecautions, including approved safety goggles, lab aprons or coats, andgloves. Know and follow all school district guidelines for lab safety and fordisposal of laboratory wastes.

Laboratory 10. Physiology of the Circulatory System

Overview

Objectives

ContentStandards

TimeRequirements

Safety

• If an inflated sphygmomanometer cuff is left on an arm for too long, thelack of blood supply below the cuff can result in tissue damage.

• Before beginning Activity B, determine if any student has a knowncondition that would make participation as a subject undesirable. Anysuch individuals can be data recorders only. On rare occasions, a studentmay become dizzy or faint upon suddenly standing. Be alert for this, and ifit occurs, seat the student with his or her head lowered between the kneesuntil the sensation passes.

• Although it is possible for students to do activities A and B in pairs, werecommend that students work in groups of four. This arrangement makesone or two students available to “spot” for each test subject, to catch orsteady the subject if needed.

Photocopy the blackline master Student Guide for each student or group of students. Photocopy the graph template at the end of the Student Guide as needed.

If time allows, review AP® Biology Lab 5: Cell Respiration either before this labor at some time between the exercises of this lab. A class discussion could helpstudents make connections between the two labs that they might otherwise miss.

As noted in the safety section, we recommend that students perform activitiesA and B as teams of four. This arrangement makes one or two studentsavailable to intervene if a student test subject needs assistance. Moreover,students can share and even rotate the various responsibilities necessary tocomplete the activities. For example, students can assume the roles of testsubject, examiner, data recorder, and timer. You may wish to have studentsswitch roles and repeat the tests for another member of the group. If yourstudents are not to work in groups of four, modify these instructions and theStudent Guide content accordingly.

Activity A: Measuring Blood PressureUse alcohol swabs to clean the stethoscope earpieces before and after use. Toallow students to hear pulse sounds while taking blood pressure readings, thenoise level in the room should be minimal.

Pulse sounds are medically known as Korotkov (or Korotkoff) sounds. Thesesounds are caused by the vibration of the arterial wall as spurts of blood surgeunder the sphygmomanometer cuff and by the turbulent flow of the bloodsqueezing through the narrowed artery into the fully opened artery below thecuff. The sounds are used to establish the systolic and diastolic pressure levelsand are recognized through the following five phases:

Phase 1: The first sounds heard are clear tapping sounds that increase inintensity. Systolic pressure is read as the first regular tapping soundduring deflation of the cuff.

Phase 2: During further deflation, a softer, muffled sound or murmur replacesthe clear tapping sounds of Phase 1.

Phase 3: A less clear but louder tapping sound replaces the murmur of Phase 2.

4 T e a c h e r ’ s M a n u a l C a r o l i n a TM A P® T e c h S u p p o r t : 8 0 0 . 2 2 7 . 1 1 5 0 e x t 4 3 0 4 a n d e x t 4 3 8 1

L a b o r a t o r y 1 0 . P h y s i o l o g y o f t h e C i r c u l a t o r y S y s t e m

PreparationandPresentation

Phase 4: A sudden change from the louder tapping of Phase 3 to a muffled,soft, “blowing” sound can be heard. The muffling of sound at thebeginning of Phase 4 is the point at which diastolic pressure is read.

Phase 5: The sound fades. Diastolic pressure can also be read here, and isusually closer to the true diastolic pressure. Phase 4 is used forreading diastolic pressure because it is less variable and gives farmore reproducibility in recording the data. Often after exercise, andin certain diseased states, the Korotkov sounds never completelydisappear. It has also been shown that it is less difficult for anexaminer to distinguish changes in sound than the disappearance ofsound, especially if there is background noise. If there is a widedifference between the onsets of the 4th and 5th phases, thepressure is recorded using both (i.e., 120/82/76).

Note that Korotkov sounds are not heart sounds. Heart sounds can be heardby placing the bell of a stethoscope over the heart. The heart sounds are acontinuous “lubb-dub” sound. The “lubb” is the sound of vibrations set up bythe closing of the valves between the atria and the ventricles and by theopening of the valves between the ventricles and the arteries. This occurswhen the ventricles contract. The “dub” is the sound of vibrations set up bythe closing of the valves between the ventricles and the arteries.

Activity B: Testing Physical FitnessFor the step test, students need stools or steps that are 45–50 cm(approximately18″) high, as well as a stopwatch or other timing device.

Activity C: Heart Rate of DaphniaNote: This kit includes a coupon for prepaid delivery of a Daphnia magnaculture. Return the coupon two to three weeks prior to the desired deliverydate to ensure timely arrival of the culture. Use the Daphnia culture as soonafter receipt as possible. Daphnia are especially sensitive to metal ions insolution, so avoid exposing the animals to metal instruments or to water thathas been in metal pipes.

In most cases you will have to cut back the tips of the dropping pipets tocreate an opening large enough to admit the Daphnia. The Daphnia should belarge enough that they will become trapped between the two depression slidesand unable to move. If the Daphnia are small enough to swim around in thechamber formed by two depression slides, it will be necessary to immobilizethem. Do this by adding a few cotton fibers to the water in the depression.The Daphnia will become entangled in the fibers and unable to move. Thefibers might partially obscure one side of the animal, so students may have toview both sides of the slide to find the least obstructed view of the heart.

At a minimum, students should have access to water baths of three differenttemperatures: room temperature, above room temperature, and below roomtemperature. However, access to four or more water baths is better, especiallyif you expect students to calculate a Q10 value for Daphnia (see OptionalActivities) If you do not have temperature-controlled water baths, useinsulated containers and thermometers. A temperature range of 5̊ C to 35̊ Cis suitable for testing Daphnia.



Station SetupFollowing is a list of the materials needed for one group of students to performthe exercises in this lab. Prepare as many setups as needed for your class.

Note: Four classroom blood pressure sets (sphygmomanometer andstethoscope) are included with the eight-station kit. Two teams of fourstudents should share each set of instruments. You may wish to have somegroups take and record blood pressure readings (Activity A and Activity B,Test 1) while other groups begin measuring pulse rates for the physical fitnesstests (Activity B, Tests 2–5).

Exercise A Exercise B Exercise Csphygmomanometer 1 1stethoscope 1 1alcohol swab 2 2*stool or chair 1

*stopwatch or clock with1 1 1second hand

living Daphnia magna 1 or 2dropping pipet 1depression well slide 2cotton ball (optional) 1petri dish 1*rubber band 2*cup or beaker 1*stereomicroscope 1

*Not supplied.

TroubleshootingAs you might expect, Korotkov sounds are more distinct in larger, moremuscular, more physically fit individuals. It may be difficult to hear Korotkovsounds when working with a person at the other end of the body-buildspectrum. Although it is unlikely, you may identify a student for whom it is notpossible to obtain blood pressure data under classroom conditions. If so, havethe student record his or her partner’s data and then allow the partner to takesomeone else’s blood pressure.

Students may be confused by the scoring of Test 1 in which a higher score isawarded for an increase in systolic pressure. This is a test for the baroreceptorresponse time, which is generally quicker in more physically fit individuals.Upon standing, blood pressure drops. This is because there is a lag time in thebaroreceptor response to the new position, allowing blood to pool in the lowerpart of the body and resulting in a drop in blood pressure. This response timeis shorter in more physically fit people; thus, some students may respondbefore their blood pressure can be taken, and they will show an increase insystolic pressure.



Counting the heartbeat of Daphnia in Activity C can be challenging. Somestudents may not be able to keep track accurately by counting silently. Thesestudents may do better by tapping a pencil point on paper in time with theheartbeat. At the end of 10 seconds, the number of pencil tics are counted and multiplied by 6 to give the heart rate.

Activity B: Testing Physical Fitness

Analysis of Results

1. What is your age in years? Answers will vary. Note that age will affect the answers given for maximumheart rate and target heart rates.

For your age, give the following:My maximum heart rate is approximately 202 beats per minute.(220 – 18 = 202)My target heart rate is between 101 (low) and 152 (high) beats per minute.(202 × 0.50 = 101); (202 × 0.75 = 151.5)

2. Compare the results of Test 1 with the combined results of tests 3 and 4.Do you see a possible relationship between these results? If so, explain.Include the major body structures and organs involved and describetheir roles.Answers should reflect the data collected. Physically fit individuals should seethat their blood pressure responds rapidly to the change but their pulse ratechanges little, reflecting the greater stroke volume of their hearts. Students at theother extreme should find the opposite. Major organ systems and organsmentioned may include the heart, baroreceptors, medulla, arterioles, and veins.Some may also list the sympathetic and parasympathetic nerve systems, adrenalgland, kidney, and liver.

3. List the variables you tested in Activity B and their effect(s).• Body position: standing vs. reclining. Answers should reflect the data collected

and should include effects on blood pressure and pulse rate.• Change in body position from reclining to standing. Answers should reflect the

data collected.• Effect of exercise on pulse rate. Answers should reflect the data collected.

4. Why is it important that the subject’s arm be at heart level when takingblood pressure measurements?Altering the position of the arm would introduce another variable. If the arm iselevated above the heart, this might decrease the measured blood pressurebecause the blood is being pumped upward against the pull of gravity. If the armis lowered, blood may tend to pool in the arm, increasing the pressure. Studentsmay also argue that raising the arm will increase the blood pressure because theheart must pump the blood to a higher point. (Note: A class discussion canhelp students realize that blood pressure is not the same in all parts of the



Sample Answersto Questions inthe Student Guide

circulatory system, something that they might not otherwise grasp.Students could design and conduct an experiment to test this variable.)

5. Consider two large mammals: a giraffe and a rhinoceros. If both animalswere standing and relaxed, which would you expect to have the higherblood pressure? Explain your answer.The giraffe would have the higher blood pressure because its heart must pumpblood upward to the head, which is elevated far above the heart. In contrast, therhino’s head is carried at about the level of its heart.

6. An astronaut’s pulse rate on the day before launch is 65 beats per minute.After three weeks in orbit, the astronaut returns to earth. Would youexpect the astronaut’s pulse rate to have changed? Explain your answer.In orbit, the astronaut’s heart will not have to beat forcefully enough toovercome gravity; thus, the heart will weaken slightly over the three-weekperiod. Upon returning to earth, the heart must beat more quickly to supply thesame amount of blood as before. Some students may argue that the astronautcan offset this effect by exercising vigorously while in space. Students may alsobe aware of other factors such as the loss of blood volume that results fromprolonged weightlessness. (Note: The effect of prolonged weightlessness onthe cardiovascular system has been a subject of intense study, and a hugeamount of information is available on the Internet. This would be a goodsubject for a report.)

Activity C: Heart Rate of Daphnia

Sample Table 3: Heart Rate of Daphnia

Analysis of ResultsGraph the temperature and heart rate data of Daphnia. Title the graph andsupply the following information:

a. The independent variable is temperature (°C).

b. The dependent variable is heart rate (beats/minute).

Plot the independent variable on the x-axis, and the dependent variable onthe y-axis.



Temperature C̊ Heartbeats/10 sec Heart rate in beats/min(Heartbeats/10 sec × 6)

7 25 150

12 38 228

15 53 318

18 61 366

24 72 432

Sample Graph

Daphnia Heart Rate at Different Temperatures

1. Write a hypothesis that this experiment is designed to test.The heart rate of Daphnia will increase as temperature increases.

2. From your graph, how much must the temperature rise to double the heartrate of Daphnia? Round your answer to the nearest 1°C.Answers will vary according to the data collected (i.e., ~10°C).

3. Why does temperature change affect the heart rate of Daphnia?The body temperature of ectothermic organisms increases as environmentaltemperature increases. As body temperature increases, the rate of chemicalreactions and physiological activities within the organism increase. Students maydiscuss the rate of enzyme reactions vs. temperature. The rate of cellularrespiration increases, requiring more oxygen and producing more carbon dioxide.This requires an increased flow of blood, which is pumped by the heart.



Title: ___________________________________________________________________________Daphnia Heart Rate at Different Temperatures

Hea

rt R

ate

(bea

ts/m

in)

Temperature (˚C)

5 10 15 20 25 30

100

200

300

400

500

4. Suppose that you repeated this experiment by measuring the heart rates ofa person immersed in water at different temperatures, and then graphedthe results. Predict how the graph might compare to your graph ofDaphnia heart rate.The test subject’s heart rate would show little change, so there would be littleslope to the graph. Humans are endotherms and regulate their internaltemperature at a relatively constant level, so a person’s heart rate would notchange significantly with environmental temperature change. Some students maybe aware of the human “diving reflex” and take that into account in theiranswer. Some might argue that the shock of being immersed in cold water wouldcause an increase in the heart rate. Some might argue that if the person wereimmersed in cold water long enough to affect core body temperature, thenmetabolism and heart rate would increase. All of these arguments, if presentedin a logical manner, are acceptable.

5. Give at least three examples of how being ectothermic affects the behaviorof reptiles (snakes, lizards, turtles, etc.).Ectothermic organisms accomplish thermoregulation primarily through changesin behavior. They move to warm areas when it is necessary to raise their bodytemperature and they move to cool areas when it is necessary to lower their bodytemperature. For example, many desert lizards spend the night in coolunderground burrows and raise their body temperature each morning by sittingin the sun and absorbing solar radiation. If their body temperature rises too high,they will move to the shade or return to their burrow. Water turtles often bask inthe sun to raise their body temperature so they can actively swim in cold water.Most reptiles hibernate during winter when temperatures are too low for them tobe active. Other examples are possible.

Perhaps more than any other AP® Biology lab, this one lends itself to thegenesis of independent student research projects. Here are a few as examples,but student discussion should generate many more.

Question 4 of Activity B considers the effect of raising or lowering the armbeing used to take blood pressure. Students can design an experiment to testthis effect. An interesting related question is whether or not raising the otherarm would have an effect. Would supporting a weight with the other arm havean effect? What about pedaling a stationary bike or doing curls with adumbbell while having blood pressure taken?

Does improved physical fitness really bring about the changes implied by thetests in Activity B? This would require a commitment of several weeks, if notmonths, by a student or students in the mid- or lower-range of the fitnessrating, but the results would certainly be enlightening.

Students could be challenged to select one of the tests from Activity B andredesign it as a scientific experiment.

Question 4 of Activity C explores the effect on heart rate of placing a personin water of different temperatures. Although this might not be practical, wouldthere be any effect from placing a hand in ice water, room temperature water,and warm water? Would the effect diminish over a period of several minutes orwould it persist?



OptionalActivities

Daphnia has been used to test for the effects on heart rate of a bewilderingvariety of substances. A brief Internet search will likely turn up dozens ofideas, everything from aspirin to zinc oxide.

The Advanced Placement® Biology Laboratory Manual for Teachers recommendscalculating a Q10 value from the data collected in Activity C. It gives twomethods for a Q10 determination. The examples shown here are based on theSample Graph given above for heart rate at 10°C and 20°C.

Note that the first method works only when the difference between the higherand lower temperatures is 10°C.

Q10 =Rate at higher temperature

= 385

= 1.97Rate at a lower temperature 195

The more general formula, which can be used for any temperature interval is:

where

t1 = lower temperaturet2 = higher temperaturek1 = rate at temperature t1

k2 = rate at temperature t2

From this formula the Q10 for the interval between 10°C and 20°C iscalculated as follows:

Students may also be able to use data collected in Lab 5 to calculate a Q10 foroxygen consumption by germinating seeds.



Q kk 10

2

1

10 / t t2 1

=–( )

Q = =10

(10/20 – 10)385

195

38⎛

⎝⎜

⎞

⎠⎟

55

195

⎛

⎝⎜

⎞

⎠⎟

(10/10)

1= (1.97) = (1.97)

Objectives• Use a sphygmomanometer and stethoscope to measure systolic and diastolic blood pressure

• Observe the response of the human circulatory system to various factors and use the results todetermine the subject’s level of physical fitness

• Investigate the relationship of temperature and heart rate for an ectotherm

Background to Activity AThe survival of any organism depends on its ability to establish an internal environment that will keepindividual cells alive and healthy. The maintenance of this internal environment in a steady state is calledhomeostasis. In complex organisms such as humans, homeostasis can only be maintained with a transportsystem that meets a wide range of needs. The blood, heart, and circulatory vessels carry out the necessarytransport function. Contraction of the ventricles of the heart forces blood into the arteries and causes anincrease in blood pressure. As the ventricles relax, blood pressure drops. As a result, blood pressure cyclesbetween a high and a low. The highest pressure reached in the cycle is called the systolic pressure and thelowest pressure reached is the diastolic pressure. Blood pressure is expressed as the height in millimeters that it will raise a column of mercury (mm Hg). The systolic pressure is written first and the diastolicpressure second (e.g., 120/80 mm Hg). Baroreceptors located in the carotid arteries and aortic archconstantly monitor blood pressure and send nerve impulses to the brain. The brain sends nerve impulses to the heart, arterioles, and other organs to increase or decrease the blood pressure as needed.

It is standard medical procedure to take blood pressurereadings in the brachial artery of the arm, at the levelof the heart. Blood pressure is routinely measured witha sphygmomanometer (Figure 1). Thesphygmomanometer consists of an inflatable cuff, apump, a gauge graduated in millimeters of mercury,and an exhaust valve with a screw control. The cuff iswrapped around the upper arm just above the elbowand then inflated. The examiner listens for soundsfrom the brachial artery by placing the bell of astethoscope on the inside of the elbow below thebiceps. When the pressure in the cuff exceeds that inthe artery, the artery collapses and blood flow stops.The pressure in the cuff is allowed to fall gradually byopening the exhaust valve. As the pressure in the cuffdrops, it reaches a point at which the pressure of the blood forces the artery open slightly, allowing aturbulent flow of blood to pass. The turbulence sets up vibrations in the artery that are heard as soundsin the stethoscope (called Korotkov sounds). When the sound first becomes audible, it is a sharpthumping. The cuff pressure at which the sound is first heard is read as the systolic blood pressure. Aspressure in the cuff decreases, the sharp thumping sound becomes louder and then muffles. The cuffpressure at which the sound disappears is read as the diastolic pressure.

© 2 0 0 7 C a r o l i n a B i o l o g i c a l S u p p l y C o m p a n y S-1

Name/Group #

Date

Student Guide

AP® Biology Laboratory 10

Physiology of the Circulatory System

Figure 1. Using a sphygmomanometer

Activity A: Measuring Blood Pressure

MaterialsSphygmomanometer, stethoscope, alcohol swabs, timer.

IntroductionFor this activity, you will work in groups of four and will take turns measuring each other’s bloodpressure using a sphygmomanometer and stethoscope. One of you will serve as the test subject, one asthe examiner, one as the data recorder, and one as the timer. Then you will switch roles and repeat theactivity. Note: These lab results are determined for experimental purposes only. They are not a substitute forregular, professional health care and diagnosis.

ProcedureTiming is important, so read the instructions before you begin the activity. The test subject should beseated, with sleeves (if any) rolled up. The experimenter should:

• Clean the earpieces of the stethoscope with an alcohol swab before and after use.

• Never leave an inflated cuff on anyone’s arm for more than a few seconds.

1. Inspect the sphygmomanometer. Be certain that the exhaust valve is open and that the cuff iscompletely deflated.

2. Wrap the cuff snugly, but not tightly, around the upper arm 2 to 3 cm above the bend in the elbow.

3. Place the bell of the stethoscope directly below the cuff in the bend of the elbow.

4. Close the exhaust valve of the bulb (pump) and rapidly inflate the cuff by squeezing the bulb untilthe pressure gauge goes past 200 mm Hg.

5. Open the exhaust valve just enough to allow the pressure to drop slowly, by about 2–5 mm Hg/sec.

6. As the pressure falls, listen with the stethoscope for the first appearance of a clear thumping ortapping sound. The pressure at which you first hear this sound is the systolic pressure. Record thesystolic pressure in Table 1.

7. Continue to listen as the pressure falls. The sound will become muffled and then louder. When thesound disappears, note the pressure. Record this measurement in Table 1 as the diastolic pressure.

8. Open the exhaust valve to completely deflate the cuff. Allow the subject to relax for 30 to 60seconds before proceeding.

9. Repeat steps 1 through 8 two more times, to complete trials 2 and 3. Determine the subject’saverage systolic and diastolic pressures.

Table 1: Blood Pressure While Seated


Systolic Diastolic

Trial 1

Trial 2

Trial 3

Total

Average

Background to Activity BAt rest, a human heart beats about 72 times each minute and pumps 5–6 liters of blood. As a person beginsto exercise, tissues need more oxygen. The heart responds by increasing its beats per minute and thusincreasing the volume of blood circulated. Eventually the heart reaches a point at which it is physicallyimpossible for it to fill with blood and contract any faster. This is its maximum heart rate. Because allnormal hearts have the same structure and are made of the same tissues, the maximum heart rate is muchthe same for everyone at the same age. As we grow older, our heart tissues become less elastic, and themaximum heart rate decreases. Your maximum heart rate is approximately 220 minus your age.

Because the heart is largely muscle, activity causes it to increase in strength and size. This increases itsstroke volume, the amount of blood ejected per beat. Consider two people running around a track at thesame pace. They are identical in age, gender, body mass, and so on, but one is more physically fit thanthe other. Their hearts must pump the same volume of blood per minute, but the more physically fitheart can accomplish this with fewer beats. As the two run faster, their heart rates will increase untilthey reach their maximum rates. Although both hearts have the same maximum rate, the less physicallyfit heart will reach its maximum sooner, because it pumps less blood per beat. Thus, over a distance, themore physically fit heart will allow its owner to win the race.

Target heart rates are used as a way to pace your efforts when you exercise. Pacing yourself is especiallyimportant for sedentary individuals beginning a new exercise program. Your target heart rate is 50–75%of your maximum heart rate. By periodically monitoring your pulse as you exercise and by attaining yourtarget heart rate, you can effectively and safely receive the benefits of being physically active. Whenbeginning an exercise program, aim at the lowest part of your target zone (50% of your maximum heartrate). Gradually build up to the higher part of your target zone (75% of your maximum heart rate). Aftersix months or more of regular exercise, you might be able to exercise comfortably up to 85% of yourmaximum heart rate, if you wish—but you do not have to exercise that hard to stay in good condition.

Activity B: Testing Physical Fitness

MaterialsSphygmomanometer, stethoscope, alcohol swabs, timer.

IntroductionPhysical fitness involves many components and can be defined in many ways (a champion gymnast, forexample, might perform poorly in a marathon). The following tests are chosen to determine the ability ofyour cardiovascular system to adapt to change. This is one measure of general physical fitness. As youproceed, be alert to signs of dizziness or faintness in the test subject and be ready to steady or catch thesubject if you are needed. Notify your teacher of any medical condition that might make it inadvisable

for you to participate in any of these tests.

ProcedureYou will work in groups of four. One student willserve as the test subject, one as the examiner, oneas the data recorder, and one as the timer.Familiarize yourself with the procedures before youbegin. Test 1 involves taking systolic pressure with asphygmomanometer. The other tests require takingthe pulse rate. The pulse can be taken at the wristas shown in Figure 2.


Figure 2. Taking the pulse rate

Test 1: Systolic Blood Pressure From Reclining to Standing1. The subject should recline for five minutes. After five minutes, take the subject’s systolic pressure

and record it in Table 2.

2. The subject should remain reclining for two minutes after Step 1 and then stand up with arms downat the sides. Immediately take the systolic pressure and record the data in Table 2.Caution: It is possible to become dizzy after standing in this manner. If the test subject becomes unsteady,becomes pale, or complains of feeling faint, seat them at once. Instruct them to lower their head betweentheir knees and keep it down until the sensation passes.

3. Determine the change in systolic pressure by subtracting the reclining systolic pressure from thestanding systolic pressure. Record this data in Table 2.

Table 2:

Change in Systolic Pressure From Reclining to Standing

Score points for Test 1:


Reclining Systolic Pressure

Standing Systolic Pressure

Change in Systolic Pressure(Standing – Reclining)

Change (mm Hg) Points

rise of 8 or more 3

rise of 2–7 2

no rise 1

fall of 2–5 0

fall of 6 or more –1

Test 2: Standing Pulse Rate1. The subject should stand at ease for two minutes after completing Test 1. During this time, the

subject should avoid moving his or her legs.

2. After two minutes have passed, count the subject’s pulse rate for 30 seconds. Multiply the rate by 2to get beats per minute.

Standing pulse rate = ___________ beats/minute


Test 3: Reclining Pulse Rate1. The subject should recline for five minutes. (Note: After this test, the subject should remain

reclining for the beginning of Test 4.)

2. After five minutes have passed, count the subject’s pulse rate for 30 seconds. Multiply the rate by 2to get beats per minute.

Reclining pulse rate = ___________ beats/minute



Beats/min Points

60–70 3

71–80 3

81–90 2

91–100 1

101–110 1

111–120 0

121–130 0

131–140 –1

Beats/min Points

50–60 3

61–70 3

71–80 2

81–90 1

91–100 0

101–110 –1

Test 4: Pulse Rate From Reclining to Standing1. Have the subject (still reclining from Test 3) stand up.

2. Immediately take the subject’s pulse. Count the number of beats for 30 seconds, then multiply therate by 2 to get beats per minute.

Pulse rate immediately upon standing = ___________ beats/min

3. Now, subtract the reclining pulse rate determined in Test 3 from the pulse rate immediately uponstanding to get the pulse rate increase upon standing.

_________________ – _________________ = ________________pulse upon standing – reclining rate, Test 3 = pulse rate increase


Test 5: Step Test1. Have the subject stand in front of a bench that is 45–50 cm high. On command the subject steps up

onto the bench, first with one foot, then the other. The subject then steps down in the same manner.Allow three seconds for each complete up-and-down movement. Repeat five times in rapid succession.

2. Immediately after the fifth down-step, take the subject’s pulse rate for 15 seconds and record it belowin the space for “Pulse beats for the 0-to-15-second interval.” Repeat at the intervals given below(16-to-30, 31-to-60, and so on) and record the data, then determine the beats/min for the intervalcounted. Note that the first two intervals are 15 seconds long (multiply by 4 to get beats/min) andthe others are 30 seconds long (multiply by 2 to get beats/min). Then, use this data to determine thepulse rate increase for each interval.*

Pulse beats for the 0-to-15-second interval: _________ × 4 = _________ beats/min

Pulse rate increase = _________




0–10 11–18 19–26 27–34 35–43

50–60 3 3 2 1 0

61–70 3 2 1 0 –1

71–80 3 2 0 –1 –2

81–90 2 1 –1 –2 –3

91–100 1 0 –2 –3 –3

101–110 0 –1 –3 –3 –3

Points

Pulse Rate Increase Upon Standing (# beats)Reclining

Pulse(beats/min)







*Pulse rate increase = beats/min for interval – standing pulse rate (from Test 2)

Score points for Test 5 based on the pulse rate increase:

Now, score points for Test 5 again, this time on the basis of time required for the pulse rate toreturn to the level recorded in Test 2:


0–10 11–20 21–30 31–40 41+

60–70 3 3 2 1 0

71–80 3 2 1 0 –1

81–90 3 2 1 –1 –2

91–100 2 1 0 –2 –3

101–110 1 0 –1 –3 –3

111–120 1 –1 –2 –3 –3

121–130 0 –2 –3 –3 –3

131–140 0 –3 –3 –3 –3

Points

Pulse Rate Increase (# beats)Standing

Pulse Rate(beats/min)

Seconds Points

0–30 4

31–60 3

61–90 2

91–120 1

*121+ 0/–1

*If 1–10 beats above standing pulse rate, score 0 points. If 11–30 beats above standing pulse rate, score –1 point.

Fitness Score: Add your scores for all of the tests (remember that there are two scores for Test 5) andrecord your total score here:

Total Score = _________ points

Analysis of Results, Activity B: Testing Physical FitnessUse your Total Score to identify your relative fitness level:

1. What is your age in years? _________ Refer to “Background for Activity B.” For your age, give the following:

My maximum heart rate is approximately _________ (220 – your age) beats per minute.

My target heart rate is between _________ (low) and _________ (high) beats per minute.

2. Compare the results of Test 1 with the combined results of tests 3 and 4. Do you see a possiblerelationship between these results? If so, explain. Include the major body structures and organsinvolved and describe their roles.

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Total Score Relative Fitness

18–17 Excellent

16–14 Good

13–8 Fair

7 or less Poor

3. List the variables you tested in Activity B and their effect(s).

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4. Why is it important that the subject’s arm be at heart level when taking blood pressuremeasurements?

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5. Consider two large mammals: a giraffe and a rhinoceros. If both animals were standing and relaxed,which would you expect to have the higher blood pressure? Explain your answer.

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6. An astronaut’s pulse rate on the day before launch is 65 beats per minute. After three weeks inorbit, the astronaut returns to earth. Would you expect the astronaut’s pulse rate to have changed?Explain your answer.

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Background to Activity CThe metabolism of many animals does not enable them to maintain a constant body temperatureindependent of their environment. Such animals are called ectotherms. From approximately 5˚C to35˚C, the rate of metabolism in these animals increases as environmental temperatures increase.

Activity C: Heart Rate of Daphnia

MaterialsStereomicroscope, timer, cup or beaker, 2 rubber bands, 2 depression well slides, petri dish, droppingpipet, living Daphnia magna.

IntroductionDaphnia magna is an ectotherm. It is a small crustacean commonly found in freshwater ponds and lakes.It uses its large antennae like oars, propelling its body rapidly forward as the antennae snap backwards.This jump-like movement gives Daphnia its common name, the water flea. Daphnia is highly transparentand all of its internal organs are visible. Its heartbeat can be observed with a stereomicroscope.

ProcedureIn this exercise, you will use Daphnia to study the effect of environmental temperature on the heart rate ofan ectotherm. Your teacher has set up water baths at different temperatures for you to use in your tests.

1. Obtain two concave-depression well slides. Place the slides side-by-side on your workspace withtheir concavities facing upward.

2. Add a Daphnia to the concavity of one slide, in a small volume of culture fluid.

3. Pick up the second depression slide and flip it over. Place this slide, concavity side down, on top ofthe first slide so that their matching concavities form a shallow pool that holds the Daphnia. Userubber bands to secure the slides together tightly (Figure 3).

Figure 3. Secured, combined concavity slides

4. Place the combined slides in a petri dish. Place the dish on the stage of a stereomicroscope.

5. Observe the Daphnia. Refer to Figure 4. Identify and note the position of the organism’s heart,dorsal to the intestine. Do not confuse the motion of the second antennae with the beating of the heart.


Figure 4. Daphnia anatomy

6. Use a cup or beaker to obtain a sample of room temperature water. Record the water temperature inTable 3. Slowly pour water into the petri dish until the bottom of the dish is covered. Stop beforewater covers the top of the upper slide.

7. Working together, one student should count heartbeats while another keeps time. Count theheartbeat for 10 seconds and record the data in Table 3.

8. Discard the water in the petri dish.

9. Obtain a sample of water with a different temperature. Repeat steps 6 through 8 using water with adifferent temperature each time. Continue until you have tested water from all the water baths oryou reach a temperature at which the heart beats too rapidly for you to count.

10. For each water temperature, determine heart rate in beats per minute and record the data in Table 3.


1. Rostrum2. Exopodite of Antenna3. Compound eye4. Supraesophageal ganglion5. Right midgut caecum6. Antenna abductor muscle 17. Esophagus8. Antenna abductor muscle 29. Antenna levator muscle10. Shell gland11. Heart12. Intestine13. Egg14. Brood sac or chamber15. Roof of food groove16. Median dorsal process17. Midgut, posterior portion

18. Caudal seta19. Hindgut20. Anus21. Abreptor22. Trunk appendage V, medial lobe23. Caudal furca24. Trunk appendage IV, endite25. Carapace26. Trunk appendage III, endite27. Metepipodite28. Trunk appendage II29. 1st maxilla30. Mandible31. Trunk appendage I32. Chemosensory setae33. Eye muscle

Table 3: Heart Rate of Daphnia

Analysis of Results, Activity C: Heart Rate of DaphniaGraph the temperature and heart rate data of Daphnia. Title the graph and supply the followinginformation:

a. The independent variable is ________________________________________.

b. The dependent variable is ________________________________________.

Plot the independent variable on the x-axis, and the dependent variable on the y-axis.

1. Write a hypothesis that this experiment is designed to test.________________________________________________________________________________

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2. From your graph, how much must the temperature rise to double the heart rate of Daphnia? Roundyour answer to the nearest 1°C. _________ °C

3. Why does temperature change affect the heart rate of Daphnia?________________________________________________________________________________

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Temperature C̊ Heartbeats/10 secHeart rate in beats/min(Heartbeats/10 sec × 6)

4. Suppose that you repeated this experiment by measuring the heart rates of a person immersed inwater at different temperatures, and then graphed the results. Predict how the graph might compareto your graph of Daphnia heart rate.________________________________________________________________________________

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5. Give at least three examples of how being ectothermic affects the behavior of reptiles (snakes,lizards, turtles, etc.).________________________________________________________________________________

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Title: ___________________________________________________________________________

Label (x-axis): ___________________________________________

Lab

el (y

-axis

): _

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