BIO 360: Vertebrate Physiology Lab 11: Heart rate and Blood Pressure
Lab 11: Circulation: Heart rate and Blood pressure response to exercise Lab Report DUE 4/9 Heart rate The circulatory system is responsible for the internal transport of many vital substances in humans, including oxygen, carbon dioxide, and nutrients. The components of the circulatory system include the heart, blood vessels, and blood. Heartbeats result from electrical stimulation of the heart cells by the pacemaker, located in the heart’s inner wall of the right atrium. Although the electrical activity of the pacemaker originates from within the heart, the rhythmic sequence of impulses produced by the pacemaker is influenced by nerves outside the heart. Many things might affect heart rate, including the physical fitness of the individual, the presence of drugs such as caffeine or nicotine in the blood, and the age of the person. As a rule, the maximum heart rate of all individuals of the same age and sex is about the same. However, the time it takes individuals to reach that maximum level while exercising varies greatly. Since physically fit people can deliver a greater volume of blood in a single cardiac cycle than unfit individuals, they can usually sustain a greater work level before reaching the maximum heart rate. Physically fit people not only have less of an increase in their heart rate during exercise, but their heart rate recovers to the resting rate more rapidly than unfit people. Blood Pressure Blood pressure is a measure of the changing fluid pressure within the circulatory system. It varies from a peak pressure produced by contraction of the left ventricle, to a low pressure, which is maintained by closure of the aortic valve and elastic recoil of the arterial system. The peak pressure is called systole, and the pressure that is maintained even while the left ventricle is relaxing is called diastole (Figure 1). Constant pressure is required to pump blood through the circulatory system. This ensures the delivery of oxygen and nutrients to and the removal of carbon dioxide and waste products from tissues. The sensitivity of blood pressure to harmful external or internal injuries makes it useful as a vital sign, an indicator of health, disease, excitement, and stress. It is usually reported with the systolic pressure stated first and the diastolic pressure stated second. In adults, 120/80 and below is considered normal while 140/90 or above is considered high. High blood pressure is a major risk factor for a number of health problems including strokes and congestive heart failure. Diet and exercise are beneficial, but many people require medication for optimal blood pressure control. In part one of this experiment, you will evaluate your physical fitness. You will use a rating system to “score” fitness during a variety of situations -­‐ in a resting position, in a prone position, and during and after physical exercise. In part two, you will examine your blood pressure in response to exercise. You will compare blood pressure readings taken before and after exercise and measure changes in systolic and diastolic arterial pressures. You will also consider the effect that exercise has on cardiac output and peripheral vascular resistance. OBJECTIVES • Determine the effect of body position on heart rates. • Determine the effect of exercise on heart rates and blood pressure. • Compare changes in systolic and arterial pressures with exercise. • Use blood pressure readings and pulse to infer changes in cardiac output and peripheral vascular resistance with exercise. • Correlate the fitness level and resting blood pressure of individuals with factors such as smoking, the amount of daily exercise, and other factors identified by students. PART 1: Heart Rate MATERIALS • computer • Vernier computer interface • Hand-­‐Grip Heart Rate Monitor PROCEDURE 1. Each person in a lab group will take turns being the subject and the tester. 2. The receiver and one of the handles are marked with a white alignment arrow as shown in Figure 2. Have the subject grasp the handles of the Hand-­‐Grip Heart Rate Monitor so that their fingers are in the reference areas indicated in Figure 2. Hold the handles vertically. 3. Have someone else hold the receiver near the handles so that the two alignment arrows are pointing in the same direction and are at approximately the same height as shown in Figure 2. Note: The receiver must stay within 60 cm of the handles during data collection. 4. Prepare the computer for data collection by opening the file “27 Heart Rate & Fitness” from the Biology with Vernier folder of LoggerPro. 5. Click “COLLECT” to begin monitoring heart rate. Note that there may be up to a 30 second delay before data are seen. 6. Determine that the sensor is functioning correctly. The readings should be within the normal range of the individual, usually between 55 and 80 beats per minute. Click “STOP” when you have determined that the equipment is operating properly. Standing heart rate 7. Click to begin monitoring heart rate. Stand upright for 2 minutes. 8. Use the resulting heart rate to assign fitness points based on Table 1 and record the values in Table 6. 2
Reclining heart rate 9. Recline on a clean surface or table for 2 minutes. Note: remember to move the receiver along with the handles to keep the arrows aligned. 10. Assign fitness points based on Table 2 and record the values in Table 6. Heart rate change from reclining to standing 11. Stand up next to the lab table. 12. Immediately record the peak heart rate in Table 6. 13. Subtract the reclining rate value in Step 10 from the peak heart rate after standing to find the heart rate increase after standing. 14. Locate the row corresponding to the reclining heart rate from Step 10 in Table 3. 15. Use the calculated heart rate increase after standing (from Step 14) to locate the proper column for fitness points in Table 3. Record the fitness points in Table 6. 16. Rest for 2 minutes. Click “STOP” to end data collection. When the rest period is over, click “COLLECT” to begin data collection. Running in place test 17. Before performing the test, record the subject’s heart rate (Pre-­‐exercise) in Table 6. 18. Run in place for one minute. Record the heart rate in Table 6. Quickly move to Step 19. Recovery rate 19. With a stopwatch or clock, begin timing to determine the subject’s recovery time. During the recovery period, the subject should remain standing and relatively still. Monitor the heart rate readings and stop timing when the readings return to the pre-­‐
exercise heart rate value. Record the recovery time in Table 6. 20. Click “STOP” to end data collection. 3
21. Locate the subject’s recovery time in Table 4 and record the corresponding fitness point value in Table 6. If the subject’s heart rate did not return to within 10 beats/min from their pre-­‐exercise heart rate, record a value of 6 points. Endurance test 22. Subtract the subject’s pre-­‐exercise heart rate from his or her heart rate after exercise. Record this heart rate increase in the endurance row of Table 6. 23. Locate the row corresponding to the pre-­‐exercise heart rate in Table 5 and use the heart rate increase value to determine the proper fitness points. Record the points in the Endurance row of the Points column in Table 6. 26. Total all the fitness points recorded in Table 6. Determine the subject’s personal fitness level using the scale below. 4
PART 2: Blood pressure MATERIALS • Omron Blood Pressure Monitor • towel • watch with second hand or stopwatch PROCEDURE 1. Sit with feet on floor, upper arm exposed. 2. Wrap cuff around upper arm and rest arm on the table. Sit with feet flat, legs uncrossed. 3. Press start and cuff will begin to inflate. 4. Record the systolic and diastolic arterial pressures and the pulse. (These values will be displayed on the monitor screen. When the blood pressure readings have stabilized (after the pressure drops to 50 mm Hg), the program will stop calculating blood pressure. At this point, you can terminate data collection by clicking . Release the pressure from the cuff, and remove the cuff from the subject’s arm. 5. Enter the systolic, diastolic, and mean arterial pressures in Table 7. 6. Run in place for 2 minutes (or perform your favorite exercise!) 7. Repeat steps 1-­‐5. Table 7. Blood pressure before and after exercise Systolic pressure Diastolic pressure Pulse (mm Hg) (mm Hg) (bpm) Before exercise After exercise DATA ANALYSIS Before leaving lab, enter your data into the spreadsheet for the class. You will use this information to calculate the average for each of the variables. I will compile the results and upload them as an excel spreadsheet to the course website. You will need these data to complete your lab report. 5
LAB REPORT For this lab, you will turn in copies of tables 6 and 7 with your summarized data filled in. You may choose to combine these tables into a single table, if appropriate. Like before, I ask that you copy and paste these tables, formatted appropriately, into a SINGLE word document along with the answers to the questions below. 1. How did your heart rate, systolic pressure, diastolic pressure, and pulse change as a result of exercise? How/why might these changes be useful in a “fight or flight” response? 2. Using the following scale, comment on the overall health of the class – was the average blood pressure in the normal/excellent scale? What factors may have contributed to readings that are outside of normal? How did your baseline data compare to the rest of the class’s data? 3.
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Describe the trends that occurred in the systolic pressure, diastolic pressure, and pulse with exercise. Assume that the stroke volume increased from 75 mL/beat to 100 mL/beat. Use this information and the change in pulse with exercise to calculate the change in cardiac output (stroke volume × heart rate) that occurred per minute. Pulse is the difference between systolic pressure (peak pressure during contraction of the ventricles) and diastolic pressure (the pressure that is maintained even while the left ventricle is relaxing). Describe the change in pulse pressure seen with exercise. Which component of the blood pressure is most responsible for this change? What implications does a person’s heart rate response (both immediately following and the recovery time) have on their overall health and fitness? How might a person work to improve these numbers? Were any of the factors from the class data associated with heart rate, recovery time, blood pressure, and/or pulse? If so, explain these. Include graphs in your answer. 6