Lab 13

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South Mountain Community College *

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160

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Biology

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Dec 6, 2023

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Fall 2019 BIO160 Name(s): _____Evelyn Alvarado________________________________________ Date: _______________________________ Class days/times ___________________________________ Lab 13: Blood Pressure and Pulse Online lab This is a modified version of the lab done in class Blood flow refers to the movement of blood through a vessel, tissue, or organ. Ventricular contraction ejects blood into the major arteries (aorta and pulmonary trunk). Then, blood continues to follow a pressure gradient as it travels through smaller arteries, arterioles, capillaries, venules, and veins. Blood pressure is the force exerted by blood upon the inner walls of the blood vessels. The term blood pressure without any specific descriptors typically refers to systemic arterial blood pressure—that is, the pressure of blood flowing in the arteries of the systemic circulation. In clinical practice, this pressure is measured in mm Hg and is usually obtained using the brachial artery of the arm. Figure 20.10 Systemic Blood Pressure The graph shows the components of blood pressure throughout the blood vessels, including systolic, diastolic, mean arterial, and pulse pressures. Heart rate (HR) can be measured by using a stethoscope to auscultate , or listen, to heart sounds. Each heartbeat is detected as a series of two sounds. In a normal, healthy heart, the first sound is created by the closing of the atrioventricular valves during ventricular contraction and is normally described as a “lub” sound. The second heart sound is created by the closing of the semilunar valves during ventricular diastole and is described as a “dub” sound. The term murmur is used to describe an unusual sound coming from the heart that is caused by the turbulent flow of blood. Murmurs are graded on a scale of 1 to 6, with 1 being the most common, the most difficult sound to detect, and the least serious. The most severe is a 6. HRs vary considerably, not only with exercise and fitness levels, but also with age. Newborn resting HRs may be 120 bpm (beats per minute). HR gradually decreases until young adulthood and then gradually increases again with age. For an adult, normal resting HR will be in the range of 60–100 bpm. Bradycardia is the condition in which resting rate drops below 60 bpm, and tachycardia is the condition in which the resting rate is above 100 bpm. 1

Fall 2019 BIO160 Activity 1: Auscultation of heart sounds Materials needed: ● Stethoscope (If you don’t have stethoscope, put your ears on the subject’s chest) ● Alcohol swab ● Watch or stopwatch ● A test subject (friend, family member etc.) Procedure: Heart Sounds at REST 1. Place a stethoscope or your ears on subject’s chest and listen for a heart sound. Locate the area where the heart sounds are loudest. 2. After 1 min. of moderate exercise, listen to your subject’s heart sounds again. Data/Questions: 1. Indicate on the diagram where you located the clearest sound. Upper left cavity 2. Did the sound of your heartbeat change after exercise? Describe what differences you heard. The heartbeat raised and is faster compare to before. 3. What is the subject’s heart rate per minute (include units)? 101 heartbeats per minute 4. What causes the first heart sound The first heart sound is caused by the closures of the right and left atrioventricular 5. What causes the second heart sound? The second heart sound is caused by the closure of the semilunar valves. Palpating Pulse After blood is ejected from the heart, elastic fibers in the arteries expand to accommodate the blood, then recoil. This expansion and recoiling effect is known as the pulse . Because pulse indicates heart rate, it is measured clinically to provide clues to a patient’s state of health. It is recorded as beats per minute (bpm). Pulse can be palpated manually by placing the tips of the fingers across an artery that runs close to the body surface and pressing lightly. While this procedure is normally performed 2

Fall 2019 BIO160 using the radial artery in the wrist or the common carotid artery in the neck, any superficial artery that can be palpated may be used (see image for arteries that can be used to detect pulse). Activity 2: Materials needed: ● Watch or stopwatch Procedure: PLUSE at REST 1. Place your first and second finger in the groove between the radius bone (on thumb side) and the tendon at the wrist and press ligh tly. 2. Count the number of beats in 10 seconds. 3. Multiply this by 6 to get the number of beats in 60 seconds (this # your pulse). 4. Skip the part that says class average. beats/10 sec. Pulse (beats/60 sec.) Class (avg.) 13 78 Data/Questions: 1. What was the subject’s heart rate based on pulse palpation? 2. Which artery is felt when taking the pulse at the wrist? The radial artery is felt when taking the pulse at the wrist. 4. Which artery is felt when taking the pulse at the neck? The carotid artery is felt when taking pulse at the neck. Measuring blood pressure using a sphygmomanometer When systemic arterial blood pressure is measured, it is recorded as a ratio of two numbers expressed as systolic pressure over diastolic pressure. For example, normal adult blood pressure is 120/80. The systolic pressure is the higher value (typically around 120 mm Hg) and reflects the arterial pressure resulting from the ejection of blood during ventricular contraction, or systole. The diastolic pressure is the lower value (usually about 80 mm Hg) and represents the arterial pressure of blood during ventricular relaxation, or diastole. The technique used today was developed more than 100 years ago by a pioneering Russian physician, Dr. Nikolai Korotkoff. Turbulent blood flow through the vessels can be heard as a soft ticking while measuring blood pressure; these sounds are known as Korotkoff sounds . The technique of measuring blood pressure requires the use of a sphygmomanometer (a blood pressure cuff attached to a measuring device) and a stethoscope. Activity 3: If you have a blood pressure machine at home, you can do this activity using your blood pressure cuff. If not, use the video on canvas “ Blood pressure video ”. 3

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