Module 2 Lesson 1 - 4 (Lab)

Lab - Exploring Student Stress!

Introduction

Consider how you feel when you worry about examinations, deadlines, sick friends, or a relationship with a girlfriend or boyfriend. Your body responds with a racing heart beat, sweaty hands, fast breathing, and maybe sleeplessness.

In this activity, you will measure one or, if possible, both of the following physiological changes: pulse, which is an indirect measure of heart rate (as you learned in Biology 20), and blood pressure. Measuring blood pressure is dependent on availability of a blood pressure monitor.

Problem

How does a stressful situation affect pulse (and blood pressure)?

Materials

• clock or watch with a second hand 
  

• blood pressure monitor (If you do not have a blood pressure monitor at your convenience, you can omit this step and take the pulse only.)

Optional: Many drug stores and pharmacies have blood pressure facilities or equipment available. As well, your local health unit may allow you to use a blood pressure monitor.

 

Procedure

1. Work with a partner or a small group. You are the experimenter and the other members are the subjects.
   
   
2. Using a watch with a second hand, the experimenter times the relaxation period of 2 minutes as the subject sits in a comfortable chair with eyes closed and takes deep, relaxing breaths.
   
   At the end of the relaxation period, the experimenter takes and records the subject's pulse, and if possible, his or her blood pressure. If you are measuring the pulse manually, you can count the number of pulses in 15 seconds and then multiply by 4 to obtain the heart rate per minute. In the picture, notice where the fingers are placed to feel the strongest pulse.
   
   If you are using a digital blood pressure monitor, the instructions usually are included with the machine. Blood pressure monitors often are  equipped to measure pulse as well as blood pressure. If you are using a blood pressure monitor, you can leave the cuff on the subject for the next step. These values provide baseline data of your subject in a relaxed state.


3. Let your subject relax for 10 minutes. At the end of the 10 minutes, shout "Time's up!" to startle the person. Immediately, take and record the subject's pulse and, if possible, the blood pressure. Record again after 2 minutes, and again 2 minutes after that. You should have a total of four readings.


4. Ask your subject to stand and do jumping jacks for 2 minutes. At the end of 2 minutes, immediately take and record the subject's pulse and, if possible, the blood pressure. Record again after 2 minutes, and again 2minutes after that. You should have a total of four readings.

 

 

Data

Organize your data for each subject in tables similar to this:

	Blood Pressure	Pulse
Reading 1
Reading 2
Reading 3
Reading 4

Analysis

Consider the answers to questions such as these:

1. Did the pulse and blood pressure change while the subject was taking the test?


2. Besides an increase in pulse and blood pressure, what other physiological changes might have occurred in the subject while he or she was startled or doing the exercise?
   Hint: See page 397 in the text.


3. How would the physiological changes that you identified in Question #2 be useful responses in a life-threatening situation?

Conclusion

In this lab, both the nervous and endocrine systems brought about the physiological changes that you measured.

• What conclusion can you make from this lab as to how a stressful situation affects pulse and blood pressure?
  
• Which parts of the nervous and endocrine systems were involved?
  
• What can you conclude about the body's ability to recover from stressful situations?
  
• How were the nervous and endocrine systems involved in this recovery?
  

Write a response to these questions and keep it in your notes.