Anatomy and physiology labs

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Introduction to ScienceExperiment 2Stress Response Experiment Inventory

Materials *Stopwatch

*Paper Towel

*Ice

*Water

*(2) Participants

Labware Sphygmomanometer (Blood Pressure Cuff)

Stethoscope

*Bucket or Deep Bowl (deep enough to sub-

merge participant’s hand)

Note: You must provide the materials listed in *red.

EXPERIMENT 2: STRESS RESPONSE

A number of different environmental factors can elicit physiological stress responses from the body. Some of the most common trig gers are temperature, exercise, pain, posture, and noise. In this experiment, you will test the body’s natural response to temperature and posture by measuring blood pressure and/or heart rate.

Note: One participant should monitor the subject throughout the experiment. Participants should remain at tentive in case the subject feels faint or dizzy.

PROCEDURE

PART 1 - TESTING TEMPERATURE

1. Develop a hypothesis regarding how decreased body temperature might affect heart rate and blood pressure. Record your

hypothesis in the post-lab questions.

2. Fill a deep bowl or bucket (large enough to submerge your participant’s hand) 50% full with ice cubes. Fill the container with

cool water until the ice cubes are covered.

Note: Be sure to leave enough space at the top of the container empty to compensate for displacement when

the participant’s hand is immersed.

3. Ask one participant to roll up his/her sleeve or change into a short-sleeved shirt to expose the bare skin of the forearm.

© eScience Labs, 2016

4. Wrap the blood pressure cuff around the subject’s forearm. Blood pressure cuffs are traditionally

placed between the elbow and shoulder but may be placed below the elbow if the upper arm is too

large to accommodate the cuff.

Figure 6: Diaphragm placement.

Note: Blood pressure readings taken below the elbow are typically not as accu

rate as readings obtained above the elbow.

5. Verify that the cuff is evenly positioned around the circumference of the forearm, lining up the patch

that says “artery” with the participant’s brachial artery. Place the diaphragm of the stethoscope on the brachial artery (see

Figure 6), and secure the cuff with the Velcro®. Be sure that the cuff is not so tight that it causes pain. The gauge should be

clipped to a flat sturdy surface, not to the cuff.

6. Have the participant sit comfortably for 5 minutes, keeping the ice water and stopwatch within arm’s reach. If possible, ele-

vate the arm with the cuff to heart-level by resting it on a piece of furniture. Do not hold the arm out in the air without support,

as this may result in muscle fatigue.

7. After 5 minutes have passed, palpate the participant’s pulse by placing your index and middle fingers on the radial artery (lo-

cated on the anterior side of the participant’s wrist). Count the number of heartbeats in 15 seconds, and multiply the value by

4. Record the total in Table 3 as beats per minute.

8. Next measure the participant’s blood pressure. To do this:

a. Insert the earpieces of the stethoscope into your ears. Inflate the cuff by closing the valve on the bulb and repeatedly

squeeze the bulb until it sounds like the blood flow has stopped. This will likely occur at approximately 130 – 180 mm

Hg.

b. Rotate the silver valve on the bulb to slowly release the cuff pressure.

c. Listen with the stethoscope for the return of blood flow into the forearm, called Korotkoff sounds.

d. Systolic pressure is the pressure at which the first sound of blood flow is heard after pressure is released.

You may also see a tapping of the needle on the pressure gauge that corresponds with the pulse.

e. As the pressure continues to decrease, blood flow returns to normal, and the Korotkoff sounds can no longer be

heard. The pressure at which this transition occurs is the diastolic pressure.

f. Record the blood pressure measurement (systolic/diastolic) in Table 3.

9. Deflate the cuff, but do not remove it from the participant’s arm.

10. Place the participant’s hand (same arm as the blood pressure cuff) in the bucket of ice water.

11. Leave the participant’s hand in the water. Measure the participant’s blood pressure and heart rate in 30-second intervals for

2 minutes. Record your data in Table 3.

Note: Remove the participant’s hand from the ice water if the temperature becomes uncomfortably cold. The

subject may stop the experiment early or try again later if necessary.

12. Remove the participant’s hand from the ice water, and pat dry with a paper towel for 2 minutes. The participant should re-

main still during this time.

13. Measure the participant’s blood pressure and heart rate a final time, and record the data in Table 3.

PART 2 - TESTING BODY POSITION

1. Develop a hypothesis regarding how postural changes might affect heart rate and blood pressure. Record your hypothesis

in the post-lab questions.

2. Ask one participant to roll up his/her sleeve or change into a short-sleeved shirt to expose the bare skin of the forearm.

3. Wrap the blood pressure cuff around the subject’s forearm. Blood pressure cuffs are traditionally placed between the elbow

and shoulder but may be placed below the elbow if the upper arm is too large to accommodate the cuff.

© eScience Labs, 2016

Note: Blood pressure readings taken below the elbow are typically not as accurate as readings obtained

above the elbow.

4. Verify that the cuff is evenly positioned around the circumference of the forearm, lining up the patch that says “artery” with

the participant’s brachial artery. Place the diaphragm of the stethoscope on the brachial artery (see Figure 6), and secure

the cuff with the Velcro®. Be sure that the cuff is not so tight that it causes pain. The gauge should be clipped to a flat sturdy

surface, not to the cuff.

5. Have the participant sit comfortably for 5 minutes. Make sure that the stopwatch is within arm’s reach.

6. After 5 minutes have passed, measure the participant’s heart rate and blood pressure. Refer to Step 8 from “Part 1 – Test-

ing Temperature” for instructions to take these measurements. Record the values in Table 4. Deflate the cuff but leave it

secured on the participant’s arm.

7. Have the participant stand up with his/her back resting against a wall for support. The participant should relax and remain

quiet. Take the subject’s initial blood pressure and heart rate. Record the values in Table 4.

8. Continue to take blood pressure and heart rate measurements at 1-minute intervals for 2 minutes. Record all measure-

ments in Table 4.

9. Sit back down comfortably for 2 minutes. Take a final blood pressure and heart rate measurement and record it in Table 4.

© eScience Labs, 2016

Data SheetExperiment 2 Data Sheet Table 3: Effect of Temperature on Blood Pressure and Heart Rate

Time Heart Rate (beats/minute) Blood Pressure

(mmHg; systolic/diastolic) Initial - Normal Temperature

30 Seconds in Ice Water

60 Seconds in Ice Water

90 Seconds in Ice Water

120 Seconds in Ice Water

Final - Dry

Table 4: Effect of Posture on Blood Pressure and Heart Rate

Time Heart Rate (beats/minute) Blood Pressure

(mmHg)

Initial - Sitting

Initial – Standing

1 Minute Standing

2 Minutes Standing

Final - 2 minutes Sitting

© eScience Labs, 2016