LAB: Blood Pressure Measurable Indicator of the Health of the Circulatory System!

Transcription

1 LAB: Blood Measurable Indicator of the Health of the Circulatory System! Lab Objectives. At the completion of the lab, you should be able to: measure pulse or heart rate (HR) and respiratory rate (RR); measure blood pressure (BP); describe the relationship between HR, RR, and BP relative to changes in body position; describe the relationship between HR, RR, and BP and isotonic. BACKGROUND INFORMATION: An important measure of the health of the circulatory system is blood pressure, or the force of the blood against the walls of the arteries in the body. Arterial blood pressure is affected by the amount of blood pumped by the heart per minute (cardiac output) and the resistance to blood flow through the arterioles (peripheral resistance). To measure arterial blood pressure, we use a device known as a sphygmomanometer (hereafter abbreviated sphyg ). This device consists of an inflatable cuff connected by rubber hoses to a hand pump and to a pressure gauge graduated in pressure units (mm Hg). The cuff is wrapped around the upper arm and inflated to a pressure greater than the expected systolic pressure, thus closing down the brachial artery in the arm. The examiner places the bell of a stethoscope in the inside of the elbow below the biceps muscle to pick up the sounds of the blood in the artery as the pressure in the cuff is allowed to fall. (This is done gradually by opening a screw valve next to the hand pump.) At first there is no sound; then, a sharp, tapping sound of blood spurting through the partially-opened artery at systolic pressure; and ultimately, no sound as even the low-pressure blood (at diastolic pressure) can get through the completely open artery. (The various sounds heard with the stethoscope are known as the sounds of Korotkoff.) Blood pressure is recorded as: systolic pressure (mm Hg) / diastolic pressure (mm Hg). A normal blood pressure measurement for a given individual depends on the person s age, sex, heredity, emotional state, body weight, etc. For young men and women at age 17-18, the normal BP s will range from mm Hg systolic pressure, and from mm Hg diastolic pressure. One high BP reading may not indicate a health problem; BP needs to be measured over several days at different times of the day by a health care professional before a true measure is achieved. Blood pressure measurements that are chronically elevated may indicate poor cardiovascular health. This condition, called hypertension, is a major contributor to heart disease and stroke.

2 EXPERIMENTAL PLAN: Materials: sphyg s, stethoscopes, stool or chair, stopwatch, data table, graph paper Procedure: *students should work in groups of 3 or 4 one should volunteer to be the subject *practice taking a classmate s pulse before collecting data *practice taking a classmate s blood pressure before collecting data *subject should practice taking their own respiratory (breathing) rate **the room must be QUIET while readings are being taken!!! 1) Take a few moments to listen to your heart and the heartbeat of the subject student. Place the bell of the stethoscope about 3 cm to the left of the sternum (breastbone) at the space between the 5 th and 6 th ribs. The heart sounds are heard as a loud lub sound followed by a softer dub sound. 2) In your lab group, assign the following roles: subject (can count their own respiratory rate), HR measurer/recorder, RR measurer/recorder, & BP measurer/recorder. 3) Take a BP measurement for practice. a) The person to have his/her BP measured should be seated, with sleeves rolled up (loosely). b) Wrap the cuff of the sphyg snugly around the upper arm. (Arm needs to be about heart height). c) Place the bell of the stethoscope directly below the cuff in the well of the elbow joint. d) Close the valve of the bulb (turn it clockwise). Inflate the cuff with rapid squeezes of the bulb until the pressure gauge reads UNDER 200 mm Hg. (Don t go higher than!) e) SLOWLY turn the valve of the bulb so that air begins to GRADUALLY escape from the cuff. f) Listen for the first heart sounds (a tapping pulse). The pressure on the gauge when you first hear these sounds is the systolic pressure. ( will be the first bounce/pause on the gauge) g) Continue to listen until the thumping sound of the heart fades to nothing. The pressure at the moment of silence is the diastolic pressure. ( last bounce/pause on the gauge) NOTE: If you failed to read the gauge correctly or missed the sounds during BP measurement, you must deflate the cuff completely and allow the subject to relax for a few minutes before starting over. 4) Do the lab!

3 BLOOD PRESSURE LAB DESIGN: Activity A: How will HR, RR, and BP change when a person stands up, after having been in a reclining position? (We are testing a reflex here!) 1) Determine a baseline HR, RR, and BP for your subject, sitting comfortably. (heart rate and respiratory rate is measured in beats per minute and breaths per minute, respectively) *Use the RADIAL PULSE for heart rate counting. *For HR and RR you can take a 15-second pulse count and then multiply that number by 4 for the number in 1 minute. 2) Next, have the subject recline on a laboratory bench for at least three minutes. At the end of this time (with the subject still reclining), measure his/her reclining HR, RR, and BP. 3) Now have your subject stand (arms at his/her side). Group members should IMMEDIATELY repeat HR, RR, and BP measurements. 4) Measure HR, RR, and BP measurements 3 minutes post- and 6 minutes post to allow us to study recovery. 5) Record all measurements as team data. Calculate the Mean Arterial for each set of data. Mean Arterial = Diastolic + 1/3 (Systolic Diastolic ) Activity B: The Harvard Step Test a measure of endurance (isotonic ). *OPTION: your group may switch the role of subject if you prefer. 1) Determine a baseline HR, RR, and BP with the subject sitting comfortably. For HR and RR you can take a 15-second count and then multiply that number by 4 for the number in 1 minute. 2) Instruct the subject to place his/her right foot on a chair (The Harvard Step Test requires an 18 inch stool!). STABILIZE THE CHAIR FOR THEM SO THEY DON T FALL. Your subject must raise his/her body so that the left foot comes to rest by the right foot. Return left foot to original position. Repeat this for 3 minutes of stepping up/down on the stool. 3) IMMEDIATELY after the completion of the stepping, measure the HR, RR, and BP. (Subject should be sitting down for the measurements) 4) Measure HR, RR and BP measurements 3 minutes post- and 6 minutes post- to allow us to study recovery. 5) Record all measurements as team data. Calculate the Mean Arterial for each set of data. Mean Arterial = Diastolic + 1/3 (Systolic Diastolic )

4 Name Date Per ACTIVITY A: Standing Reflex TEAM DATA TABLES for BLOOD PRESSURE LAB Measurements taken: 15 sec. heart rate (x 4) Breaths per minute Systolic Diastolic *Mean Arterial Baseline Lying down Right after 3-min after 6-min after *Mean Arterial = Diastolic + 1/3 (Systolic Diastolic ) ACTIVITY B: Harvard Step Test Physical Fitness Test Measurements taken: 15 sec. heart rate (x 4) Breaths per minute Systolic Diastolic *Mean Arterial Baseline Right after 3-min after 6-min after *Mean Arterial = Diastolic + 1/3 (Systolic Diastolic )

5 Blood Lab: Post Lab Questions Activity A 1) a. What happened to the MAP when a person reclines for 5 minutes? b. Why? 2) Normally, when people stand, gravity causes blood to pool in the veins of the legs and trunk. a. As the 1 st step to your body maintaining homeostasis, how would this immediately effect blood pressure & the amount of blood going to the brain? b. What molecule is the brain lacking specifically that causes the feeling of being lightheaded? c. How would the heart respond? d. What would this do to the blood pressure? e. Do you see this response in your MAP data? 3) What happens to the MAP in the recovery period after? 4) Does the breathing rate and heart rate follow the MAP trend? Activity B 1) Compare the breathing, heart rate, & MAP before, during, and after by filling in this table. Type of rate Before Exercise After Exercise Breathing Heart MAP 2) Explain why your results occurred for MAP (In other words, why does it increase or decrease?). 3 To explain how breathing and heart rate relate to, answer: (a) Would breathing and heart rate increase or decrease with? b) What 2 specific materials are being transported to muscle cells to keep them working? and c) Why are these materials needed by muscle cells (what are they being used for)? 4) How would the MAP (mean arterial pressure) be effected in a person had plaque build-up in their arteries and their arteries were no longer as flexible?