AP Biology Lab 10

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LABORATORY

10

Physiology of the

Circulatory

System

TEACHER’S MANUAL WITH STUDENT GUIDE

74-6580 8-Station Kit

74-6581 1-Station Kit

Property Measured

Length

Mass

Amount of Substance

Concentration of a Solution

Volume (gases and liquids)

Temperature (thermodynamic)

Temperature (common)

Force

Heat or Energy

Time

Pressure

Units of Measure Useful in AP

®

Biology

molarity kiloliter liter milliliter microliter

*kelvin

Celsius newton joule

**calorie

**Calorie (food)

*second millisecond pascal

**atmosphere

Bar

**Torr

Unit

*meter centimeter millimeter micrometer nanometer

*kilogram gram

Symbol m cm mm

μ m nm kg g milligram microgram

*mole mg

μ g mol mass percentage % parts per million ppm

°C

N

J cal

Cal s ms

M kL

L mL

μ

L

K

Pa atm bar torr

Description

100 cm = 10 2 cm

0.01 m = 10 –2 m

0.001 m = 10 –3 m

10 –6 m = 10 –3 mm

10 –9 m = 10 –3

μ m

1000 g

1000 mg

0.001 g = 10 –3 g

10 –6 g

6.02 x 10 23 particles (atoms, ions, or molecules)

Mass % = mass of solute/total mass of soln.

×

100 ppm of solute = mass of solute/total mass of soln.

×

10 6 or 1 ppm = 1 mg solute/L soln.

Molarity = moles solute/L soln.

1000 L

1000 mL = 1 dm 3 = 10 –3 m 3 mL = cm 3 = 10 –3 L

10 –6 L = 10 –3 mL

K = °C + 273

0°K = –273°C kg•m/s 2

N•m

4.184 J

1000 calories = 1 kcal

60 s = 1 min

10 –3 s

N/m 2 = kg/m•s 2

101,325 Pa = 101.325 kPa = 760 torr = 14.7 lb/in 2

10 5 Pa mm Hg = 133.3 Pa

* SI Base Unit

**Non-metric

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 sole responsibility for kit contents. Permission is granted to reproduce the Student Guide blackline masters at the end of this manual for use with the materials provided in the accompanying Carolina TM AP ® Biology kit or replacement set.

For complete listings of Carolina TM current Carolina TM

AP ® Science materials, including the Advanced Placement ® Biology

Laboratory Manual for Teachers

Students

(RN-74-6681) and the Advanced Placement ®

(RN-72-6682), log on to www.carolina.com/ or refer to the current

Biology Laboratory Manual for

Carolina TM Science catalog or the

Biotechnology & AP ® Biology catalog.

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

©2007 Carolina Biological Supply Company Printed in USA

Laboratory 10. Physiology of the Circulatory System

Overview

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 under different conditions to determine their level of physical fitness. In Activity C

(Heart Rate of Daphnia ) , students observe the heart rate of Daphnia at different temperatures.

Objectives

Content

Standards

Time

Requirements

Safety

• 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 to determine the subject’s level of physical fitness

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

This kit is appropriate for Advanced Placement ® high school students and addresses 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 to complete the Analysis of Results sections is not included.

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

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Preparation and

Presentation

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

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

• Although it is possible for students to do activities A and B in pairs, we recommend that students work in groups of four. This arrangement makes one or two students available to “spot” for each test subject, to catch or steady 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 lab or at some time between the exercises of this lab. A class discussion could help students make connections between the two labs that they might otherwise miss.

As noted in the safety section, we recommend that students perform activities

A and B as teams of four. This arrangement makes one or two students available to intervene if a student test subject needs assistance. Moreover, students can share and even rotate the various responsibilities necessary to complete the activities. For example, students can assume the roles of test subject, examiner, data recorder, and timer. You may wish to have students switch roles and repeat the tests for another member of the group. If your students are not to work in groups of four, modify these instructions and the

Student Guide content accordingly.

Activity A: Measuring Blood Pressure

Use alcohol swabs to clean the stethoscope earpieces before and after use. To allow students to hear pulse sounds while taking blood pressure readings, the noise level in the room should be minimal.

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

Phase 1: The first sounds heard are clear tapping sounds that increase in intensity. Systolic pressure is read as the first regular tapping sound during deflation of the cuff.

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

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

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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 the beginning 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 is usually closer to the true diastolic pressure. Phase 4 is used for reading diastolic pressure because it is less variable and gives far more reproducibility in recording the data. Often after exercise, and in certain diseased states, the Korotkov sounds never completely disappear. It has also been shown that it is less difficult for an examiner to distinguish changes in sound than the disappearance of sound, especially if there is background noise. If there is a wide difference between the onsets of the 4th and 5th phases, the pressure is recorded using both (i.e., 120/82/76).

Note that Korotkov sounds are not heart sounds. Heart sounds can be heard by placing the bell of a stethoscope over the heart. The heart sounds are a continuous “lubb-dub” sound. The “lubb” is the sound of vibrations set up by the closing of the valves between the atria and the ventricles and by the opening of the valves between the ventricles and the arteries. This occurs when the ventricles contract. The “dub” is the sound of vibrations set up by the closing of the valves between the ventricles and the arteries.

Activity B: Testing Physical Fitness

For 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 Daphnia

Note: This kit includes a coupon for prepaid delivery of a Daphnia magna culture. Return the coupon two to three weeks prior to the desired delivery date to ensure timely arrival of the culture. Use the Daphnia culture as soon after receipt as possible. Daphnia are especially sensitive to metal ions in solution, so avoid exposing the animals to metal instruments or to water that has been in metal pipes.

In most cases you will have to cut back the tips of the dropping pipets to create an opening large enough to admit the Daphnia . The Daphnia should be large enough that they will become trapped between the two depression slides and unable to move. If the Daphnia are small enough to swim around in the chamber formed by two depression slides, it will be necessary to immobilize them. 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. The fibers might partially obscure one side of the animal, so students may have to view 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 different temperatures: room temperature, above room temperature, and below room temperature. However, access to four or more water baths is better, especially if you expect students to calculate a Q

10 value for Daphnia (see Optional

Activities) If you do not have temperature-controlled water baths, use insulated containers and thermometers. A temperature range of 5˚C to 35˚C is suitable for testing Daphnia .

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Station Setup

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

Note: Four classroom blood pressure sets (sphygmomanometer and stethoscope) are included with the eight-station kit. Two teams of four students should share each set of instruments. You may wish to have some groups take and record blood pressure readings (Activity A and Activity B,

Test 1) while other groups begin measuring pulse rates for the physical fitness tests (Activity B, Tests 2–5).

sphygmomanometer stethoscope alcohol swab

*stool or chair

*stopwatch or clock with second hand living Daphnia magna dropping pipet depression well slide cotton ball (optional) petri dish

*rubber band

*cup or beaker

*stereomicroscope

*Not supplied.

Exercise A

1

1

2

1

Exercise B

1

1

2

1

1

Exercise C

1

1

1

1

2

1 or 2

1

2

1

Troubleshooting

As you might expect, Korotkov sounds are more distinct in larger, more muscular, more physically fit individuals. It may be difficult to hear Korotkov sounds when working with a person at the other end of the body-build spectrum. Although it is unlikely, you may identify a student for whom it is not possible to obtain blood pressure data under classroom conditions. If so, have the student record his or her partner’s data and then allow the partner to take someone else’s blood pressure.

Students may be confused by the scoring of Test 1 in which a higher score is awarded for an increase in systolic pressure. This is a test for the baroreceptor response time, which is generally quicker in more physically fit individuals.

Upon standing, blood pressure drops. This is because there is a lag time in the baroreceptor response to the new position, allowing blood to pool in the lower part of the body and resulting in a drop in blood pressure. This response time is shorter in more physically fit people; thus, some students may respond before their blood pressure can be taken, and they will show an increase in systolic pressure.

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Sample Answers to Questions in the Student Guide

Counting the heartbeat of Daphnia in Activity C can be challenging. Some students may not be able to keep track accurately by counting silently. These students may do better by tapping a pencil point on paper in time with the heartbeat. 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 maximum heart 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 describe their roles.

Answers should reflect the data collected. Physically fit individuals should see that their blood pressure responds rapidly to the change but their pulse rate changes little, reflecting the greater stroke volume of their hearts. Students at the other extreme should find the opposite. Major organ systems and organs mentioned may include the heart, baroreceptors, medulla, arterioles, and veins.

Some may also list the sympathetic and parasympathetic nerve systems, adrenal gland, 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 taking blood pressure measurements?

Altering the position of the arm would introduce another variable. If the arm is elevated above the heart, this might decrease the measured blood pressure because the blood is being pumped upward against the pull of gravity. If the arm is lowered, blood may tend to pool in the arm, increasing the pressure. Students may also argue that raising the arm will increase the blood pressure because the heart must pump the blood to a higher point. ( Note: A class discussion can help students realize that blood pressure is not the same in all parts of the

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Students could design and conduct an experiment to test this variable.)

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.

The giraffe would have the higher blood pressure because its heart must pump blood upward to the head, which is elevated far above the heart. In contrast, the rhino’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 you expect the astronaut’s pulse rate to have changed? Explain your answer.

In orbit, the astronaut’s heart will not have to beat forcefully enough to overcome gravity; thus, the heart will weaken slightly over the three-week period. Upon returning to earth, the heart must beat more quickly to supply the same amount of blood as before. Some students may argue that the astronaut can offset this effect by exercising vigorously while in space. Students may also be aware of other factors such as the loss of blood volume that results from prolonged weightlessness. ( Note: The effect of prolonged weightlessness on the cardiovascular system has been a subject of intense study, and a huge amount of information is available on the Internet. This would be a good subject for a report.)

Activity C: Heart Rate of Daphnia

Sample Table 3: Heart Rate of Daphnia

Temperature ˚ C Heartbeats/10 sec

Heart rate in beats/min

(Heartbeats/10 sec × 6)

12 38 228

15 53 318

18 61 366

24 72 432

Analysis of Results

Graph the temperature and heart rate data of Daphnia . Title the graph and supply 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 on the y-axis.

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Sample Graph

Daphnia Heart Rate at Different Temperatures

Daph n ia Hea r t Rate at Diffe r e n t Te m pe r atu r es

300

200

100

500

400

5 10 15 20

Te m pe r atu r e (˚C)

25 30

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 heart rate 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 environmental temperature increases. As body temperature increases, the rate of chemical reactions and physiological activities within the organism increase. Students may discuss the rate of enzyme reactions vs. temperature. The rate of cellular respiration increases, requiring more oxygen and producing more carbon dioxide.

This requires an increased flow of blood, which is pumped by the heart.

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Optional

Activities

4. Suppose that you repeated this experiment by measuring the heart rates of a person immersed in water at different temperatures, and then graphed the results. Predict how the graph might compare to your graph of

Daphnia heart rate.

The test subject’s heart rate would show little change, so there would be little slope to the graph. Humans are endotherms and regulate their internal temperature at a relatively constant level, so a person’s heart rate would not change significantly with environmental temperature change. Some students may be aware of the human “diving reflex” and take that into account in their answer. Some might argue that the shock of being immersed in cold water would cause an increase in the heart rate. Some might argue that if the person were immersed in cold water long enough to affect core body temperature, then metabolism and heart rate would increase. All of these arguments, if presented in a logical manner, are acceptable.

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

Ectothermic organisms accomplish thermoregulation primarily through changes in behavior. They move to warm areas when it is necessary to raise their body temperature and they move to cool areas when it is necessary to lower their body temperature. For example, many desert lizards spend the night in cool underground burrows and raise their body temperature each morning by sitting in 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 in the 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 to be active. Other examples are possible.

Perhaps more than any other AP ® Biology lab, this one lends itself to the genesis 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 arm being used to take blood pressure. Students can design an experiment to test this effect. An interesting related question is whether or not raising the other arm would have an effect. Would supporting a weight with the other arm have an effect? What about pedaling a stationary bike or doing curls with a dumbbell while having blood pressure taken?

Does improved physical fitness really bring about the changes implied by the tests in Activity B? This would require a commitment of several weeks, if not months, by a student or students in the mid- or lower-range of the fitness rating, but the results would certainly be enlightening.

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

Question 4 of Activity C explores the effect on heart rate of placing a person in water of different temperatures. Although this might not be practical, would there 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 or would it persist?

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

The Advanced Placement ® Biology Laboratory Manual for Teachers recommends calculating a Q

10 methods for a Q

10 value from the data collected in Activity C. It gives two determination. The examples shown here are based on the

Sample Graph given above for heart rate at 10°C and 20°C.

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

Q

10

=

Rate at higher temperature

=

385

Rate at a lower temperature 195

= 1.97

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

Q

10

= k

2 k

1

(

10 / t

2

– t

1

) where t

1 t

2 k

1 k

2

= lower temperature

= higher temperature

= rate at temperature t

= rate at temperature t

1

2

From this formula the Q

10 calculated as follows: for the interval between 10°C and 20°C is

Q =

10

385

⎞ (10/20 – 10)

=

⎝⎜ 195 ⎠⎟

38 55

⎞ (10/10)

⎝⎜ 195 ⎠⎟

Students may also be able to use data collected in Lab 5 to calculate a Q

10 oxygen consumption by germinating seeds.

for

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Name/Group #

Date

Student Guide

AP

®

Biology Laboratory 10

Physiology of the Circulatory System

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 to determine the subject’s level of physical fitness

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

Background to Activity A

The survival of any organism depends on its ability to establish an internal environment that will keep individual cells alive and healthy. The maintenance of this internal environment in a steady state is called homeostasis. In complex organisms such as humans, homeostasis can only be maintained with a transport system that meets a wide range of needs. The blood, heart, and circulatory vessels carry out the necessary transport function. Contraction of the ventricles of the heart forces blood into the arteries and causes an increase in blood pressure. As the ventricles relax, blood pressure drops. As a result, blood pressure cycles between a high and a low. The highest pressure reached in the cycle is called the systolic pressure and the lowest 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 diastolic pressure second (e.g., 120/80 mm Hg). Baroreceptors located in the carotid arteries and aortic arch constantly 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 pressure readings in the brachial artery of the arm, at the level of the heart. Blood pressure is routinely measured with a sphygmomanometer (Figure 1). The sphygmomanometer consists of an inflatable cuff, a pump, a gauge graduated in millimeters of mercury, and an exhaust valve with a screw control. The cuff is wrapped around the upper arm just above the elbow and then inflated. The examiner listens for sounds from the brachial artery by placing the bell of a stethoscope on the inside of the elbow below the biceps. When the pressure in the cuff exceeds that in the artery, the artery collapses and blood flow stops.

The pressure in the cuff is allowed to fall gradually by

Figure 1. Using a sphygmomanometer opening the exhaust valve. As the pressure in the cuff drops, it reaches a point at which the pressure of the blood forces the artery open slightly, allowing a turbulent flow of blood to pass. The turbulence sets up vibrations in the artery that are heard as sounds in the stethoscope (called Korotkov sounds). When the sound first becomes audible, it is a sharp thumping. The cuff pressure at which the sound is first heard is read as the systolic blood pressure. As pressure in the cuff decreases, the sharp thumping sound becomes louder and then muffles. The cuff pressure at which the sound disappears is read as the diastolic pressure.

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Activity A: Measuring Blood Pressure

Materials

Sphygmomanometer, stethoscope, alcohol swabs, timer.

Introduction

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

Procedure

Timing is important, so read the instructions before you begin the activity. The test subject should be seated, 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 is completely 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 until the 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 or tapping sound. The pressure at which you first hear this sound is the systolic pressure. Record the systolic pressure in Table 1.

7.

Continue to listen as the pressure falls. The sound will become muffled and then louder. When the sound 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 60 seconds before proceeding.

9.

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

Table 1: Blood Pressure While Seated

Systolic Diastolic

Trial 1

Trial 2

Trial 3

Total

Average

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Background to Activity B

At rest, a human heart beats about 72 times each minute and pumps 5–6 liters of blood. As a person begins to exercise, tissues need more oxygen. The heart responds by increasing its beats per minute and thus increasing the volume of blood circulated. Eventually the heart reaches a point at which it is physically impossible for it to fill with blood and contract any faster. This is its maximum heart rate. Because all normal hearts have the same structure and are made of the same tissues, the maximum heart rate is much the same for everyone at the same age. As we grow older, our heart tissues become less elastic, and the maximum 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 its stroke volume, the amount of blood ejected per beat. Consider two people running around a track at the same pace. They are identical in age, gender, body mass, and so on, but one is more physically fit than the other. Their hearts must pump the same volume of blood per minute, but the more physically fit heart can accomplish this with fewer beats. As the two run faster, their heart rates will increase until they reach their maximum rates. Although both hearts have the same maximum rate, the less physically fit heart will reach its maximum sooner, because it pumps less blood per beat. Thus, over a distance, the more 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 especially important 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 your target heart rate, you can effectively and safely receive the benefits of being physically active. When beginning an exercise program, aim at the lowest part of your target zone (50% of your maximum heart rate). Gradually build up to the higher part of your target zone (75% of your maximum heart rate). After six months or more of regular exercise, you might be able to exercise comfortably up to 85% of your maximum heart rate, if you wish—but you do not have to exercise that hard to stay in good condition.

Activity B: Testing Physical Fitness

Materials

Sphygmomanometer, stethoscope, alcohol swabs, timer.

Introduction

Physical fitness involves many components and can be defined in many ways (a champion gymnast, for example, might perform poorly in a marathon). The following tests are chosen to determine the ability of your cardiovascular system to adapt to change. This is one measure of general physical fitness. As you proceed, be alert to signs of dizziness or faintness in the test subject and be ready to steady or catch the subject 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.

Figure 2. Taking the pulse rate

Procedure

You will work in groups of four. One student will serve as the test subject, one as the examiner, one as the data recorder, and one as the timer.

Familiarize yourself with the procedures before you begin. Test 1 involves taking systolic pressure with a sphygmomanometer. The other tests require taking the pulse rate. The pulse can be taken at the wrist as shown in Figure 2.

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Test 1: Systolic Blood Pressure From Reclining to Standing

1.

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 down at 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 between their knees and keep it down until the sensation passes.

3.

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

Table 2:

Change in Systolic Pressure From Reclining to Standing

Reclining Systolic Pressure

Standing Systolic Pressure

Change in Systolic Pressure

(Standing – Reclining)

Score points for Test 1:

Change (mm Hg) rise of 8 or more rise of 2–7 no rise fall of 2–5 fall of 6 or more

Points

3

2

1

0

–1

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Test 2: Standing Pulse Rate

1.

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 2 to get beats per minute.

Standing pulse rate = ___________ beats/minute

Score points for Test 2:

Beats/min

60–70

71–80

81–90

91–100

101–110

111–120

121–130

131–140

1

1

0

0

–1

Points

3

3

2

Test 3: Reclining Pulse Rate

1.

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 2 to get beats per minute.

Reclining pulse rate = ___________ beats/minute

Score points for Test 3:

Beats/min

50–60

61–70

71–80

81–90

91–100

101–110

Points

3

3

2

1

0

–1

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Test 4: Pulse Rate From Reclining to Standing

1.

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 the rate 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 upon standing to get the pulse rate increase upon standing.

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

Score points for Test 4:

Reclining

Pulse

(beats/min)

50–60

61–70

71–80

81–90

91–100

101–110

Points

Pulse Rate Increase Upon Standing (# beats)

0–10 11–18 19–26 27–34 35–43

3

2

3

3

1

0

3

2

2

1

0

–1

2

1

0

–1

–2

–3

1

0

–1

–2

–3

–3

0

–1

–2

–3

–3

–3

Test 5: Step Test

1.

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 below in 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 interval counted. Note that the first two intervals are 15 seconds long (multiply by 4 to get beats/min) and the others are 30 seconds long (multiply by 2 to get beats/min). Then, use this data to determine the pulse rate increase for each interval.*

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

Pulse rate increase = _________

Pulse beats for the 16-to-30-second interval: _________ × 4 = _________ beats/min

Pulse rate increase = _________

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Pulse beats for the 31-to-60-second interval: _________ × 2 = _________ beats/min

Pulse rate increase = _________

Pulse beats for the 61-to-90-second interval: _________ × 2 = _________ beats/min

Pulse rate increase = _________

Pulse beats for the 91-to-120-second interval: _________ × 2 = _________ beats/min

Pulse rate increase = _________

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

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

Standing

Pulse Rate

(beats/min)

60–70

71–80

81–90

91–100

101–110

111–120

121–130

131–140

2

1

1

0

0

Points

Pulse Rate Increase (# beats)

0–10 11–20 21–30 31–40 41+

3 3 2 1 0

3

3

2

2

1

1

0

–1

–1

–2

1

0

–1

–2

–3

0

–1

–2

–3

–3

–2

–3

–3

–3

–3

–3

–3

–3

–3

–3

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

Seconds

0–30

31–60

61–90

91–120

*121+

Points

4

3

2

1

0/–1

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

If 11–30 beats above standing pulse rate, score –1 point.

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

Total Score = _________ points

Analysis of Results, Activity B: Testing Physical Fitness

Use your Total Score to identify your relative fitness level:

Total Score

18–17

16–14

13–8

7 or less

Relative Fitness

Excellent

Good

Fair

Poor

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 possible relationship between these results? If so, explain. Include the major body structures and organs involved and describe their roles.

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

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

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

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

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

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.

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

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 you expect the astronaut’s pulse rate to have changed?

Explain your answer.

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

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Background to Activity C

The metabolism of many animals does not enable them to maintain a constant body temperature independent of their environment. Such animals are called ectotherms. From approximately 5˚C to

35˚C, the rate of metabolism in these animals increases as environmental temperatures increase.

Activity C: Heart Rate of Daphnia

Materials

Stereomicroscope, timer, cup or beaker, 2 rubber bands, 2 depression well slides, petri dish, dropping pipet, living Daphnia magna .

Introduction

Daphnia 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 transparent and all of its internal organs are visible. Its heartbeat can be observed with a stereomicroscope.

Procedure

In this exercise, you will use Daphnia to study the effect of environmental temperature on the heart rate of an 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 with their 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 of the first slide so that their matching concavities form a shallow pool that holds the Daphnia . Use rubber 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.

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8.

9.

10.

11.

12.

13.

14.

15.

16.

17.

1.

2.

3.

4.

5.

6.

7.

Rostrum

Exopodite of Antenna

Compound eye

Supraesophageal ganglion

Right midgut caecum

Antenna abductor muscle 1

Esophagus

Antenna abductor muscle 2

Antenna levator muscle

Shell gland

Heart

Intestine

Egg

Brood sac or chamber

Roof of food groove

Median dorsal process

Midgut, posterior portion

Figure 4. Daphnia anatomy

25.

26.

27.

28.

29.

30.

31.

32.

33.

18.

19.

20.

21.

22.

23.

24.

Caudal seta

Hindgut

Anus

Abreptor

Trunk appendage V, medial lobe

Caudal furca

Trunk appendage IV, endite

Carapace

Trunk appendage III, endite

Metepipodite

Trunk appendage II

1st maxilla

Mandible

Trunk appendage I

Chemosensory setae

Eye muscle

6.

Use a cup or beaker to obtain a sample of room temperature water. Record the water temperature in

Table 3. Slowly pour water into the petri dish until the bottom of the dish is covered. Stop before water covers the top of the upper slide.

7.

Working together, one student should count heartbeats while another keeps time. Count the heartbeat 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 a different temperature each time. Continue until you have tested water from all the water baths or you 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.

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S-11

Temperature ˚C

Table 3: Heart Rate of Daphnia

Heartbeats/10 sec

Heart rate in beats/min

(Heartbeats/10 sec × 6)

Analysis of Results, Activity C: Heart Rate of Daphnia

Graph the temperature and heart rate data of Daphnia . Title the graph and supply the following information: 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.

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

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

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

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

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

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

________________________________________________________________________________

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): ___________________________________________

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