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Aaron Jacobs Tian Yu Biology 240W; Section 029 4/5/2012 The Relationship Between Gender and its Effect on Cardiovascular Fitness, Which is Measured at Rest and During Exercise by Pulse Rate, Systolic and Diastolic Blood Pressure Introduction: From a simple worm to the complex human being and all the animals in between, each one must somehow pump vital nutrients through their bodies. The circulatory system is a combination of a heart, a nutrient rich circulatory fluid and a giant web of interconnecting blood vessels. Every cell, tissue and organ requires the liquid of life, and in humans this is blood. The circulatory systems job is to transport this blood, which is full of oxygen and other nutrients crucial for life, throughout the entire body. The circulatory system is also responsible for transporting and disposing of wastes. There are two types of circulatory systems, open and closed. The type of system described above is a closed circulatory system, it is the type that humans have and is also referred to as the cardio vascular system. The other type of circulatory system is seen more in arthropods and mollusks, which is when the circulatory system just immerses the organs with a circulatory fluid known as hemolymph. For the rest of this lab, only the closed circulatory system will be looked into in more detail. The circulatory fluid found in a closed circulatory system is known as blood and unlike hemolymph, blood is restricted to blood vessels. Closed circulatory systems allow for more motion, this is seen in all larger animals because of the demand for oxygen that is required for large amounts of activity. The closed circulatory system is also adapted for regulating the amount of blood each part of the body receives. The cardiovascular system made up of many components (Jane B. Reece, 2011). The human body has 60,000 miles of vessels contained within it that is twice as long as the circumference of the earth (National Geographic). There are three major types of blood vessels; these include the arteries, veins and capillaries. There is no such thing as a two-­‐way highway in blood vessels, each one only forces blood in one direction. The oxygen rich blood, as it leaves the heart, is carried in arteries. The blood the arteries carry is taken to the organs and muscles of the body. Once at their destination, the arteries branch out to form arterioles, which eventually fan out into capillaries. Capillaries are extremely small vessels that infiltrate into the tissues of the body forming capillary beds. The capillaries defuse the oxygen and nutrient rich blood into the tissues. The tissues use the oxygen and nutrients, the blood at this point are lacking both because the tissues used them. The oxygen deprived blood flows though receiving capillaries, which transport the blood to venules. Venules eventually converge and form veins; veins are the major vessels that carry the blood back to the heart (Jane B. Reece, 2011). The heart must work continuously; it beats an average of 100,000 times in a single day (National Geographic). The heart is at the center of the cardiovascular system; it is the muscle responsible for the pumping and movement of the blood through the human body. The four-­‐chambered heart is located behind the breastbone and is made up of primarily cardiac muscle, which is what allows for the contractions of the heart. The four chambers are divided into two different types, the top two are known as the left and right atria while the bottom two are known as the left and right ventricles. The atria work as collection areas for incoming blood from both the lungs and the rest of the body. The left atrium receives the oxygen rich blood from the lungs while the right atrium receives the oxygen-­‐deprived blood from the rest of the body. Both atria have thinner walls when compared to the ventricles. The ventricles receive the blood from the atria, the left ventricle being the one that pushes the freshly oxygenized blood to the rest of the body and the right sending the resulting oxygen deprived blood back towards the lungs. The heart goes through cycles of contracting and filling known as the cardiac cycle. When the heart is contracting it is said to be in the systole phase and when it is relaxing it is said to be in the diastole phase. These contractions cause for the circulation of blood through the whole body, which it does by utilizing the physics and properties behind blood pressure (Jane B. Reece, 2011). Blood pressure is measured in this lab, along with heart rate. Arteries have to elements that contribute to blood pressure, which are peripheral resistance and cardiac output. Arterioles and capillaries contribute to keeping blood pressure from reaching zero between heartbeats by applying resistance to flow. Since capillaries are only one cell thick, muscles surrounding them along with pre-­‐capillary sphincters are able to contract in response to specific chemicals that are being released. The chemicals involved in this process are part of a feedback loop. When the sphincters are relaxed the blood flow begins to increase, this increase causes the chemicals to shift, contracting muscles and moving the blood to places at rest. Cardiac output is how much blood the left ventricle pumps per a specific unit of time. Cardiac output depends on two things, heart rate and the stroke volume, which is the volume of blood within in each heartbeat. During exercise the cardiac output can increase exponentially. Near the heart blood pressure is highest and once in the branching blood vessels that pressure goes down, one can conclude then that the blood pressure in arteries would be higher than in the veins. Since the pressure decreases, muscle contractions help veins move the blood back to the heart (Nelson, K. and Burpee, D.). During exercise the systolic blood pressure should show an increase while the diastolic blood pressure should show no change to a slight drop in pressure. Depending on the intensity of the exercise the systolic pressure will show a greater increase, the more intense the higher the systolic blood pressure (Ann, 2010). This lab looks specifically at the difference between male and females, and the relation gender plays in cardiovascular fitness. In earlier adulthood, until around the age of 60, women tend to have a lower systolic blood pressure when compared to men. Right around the age of 60, the statement above is reversed and men begin to have a lower systolic blood pressure then women. Women also tend to have a lower diastolic blood pressure, which remains that way for all ages (Oparil 2005). It was also found that women have a considerable lower ability to regulate blood pressure, which in turn would cause for a lower systolic and diastolic blood pressure (Convertino, 1998). The purposes of this lab was to collect data on cardiovascular physiology of the individuals being tested in the class and relate these values without any activity or at rest to values retrieved after exercise. Another goal was to determine the relationship between gender and the cardiovascular fitness of the individuals being tested. There are a few questions that surface because of this lab that will be answered later on. What is the relationship between gender and systolic or diastolic blood pressure before and after exercise? Along with what is the relationship between pulse count before and after exercise and the relationship that shares with gender? From the research gathered from external sources and articles, I predict that women will have a lower systolic and diastolic blood pressure when compared to men, before and after exercise. Methods and Materials: Some initial steps have to be taken before any data collection takes place. Before anything the personal history of all the people being tested has to be taken, this includes age, gender, weight, height, along with a few other questions, the only thing this lab is focusing on is the gender of the tester to make comparisons between male and female cardiovascular fitness. Some knowledge of reading heart rates and gathering blood pressure must be known before the actual experiment can begin. To find someone’s heart rate, one must place their middle and index finger on a location of the body where a heart beat can be easily felt. The reason those fingers are used is because the thumb has a very strong heart beat and by using the thumb it can be hard to determine which heart rate is being felt, the tester or the person being tested. These locations include, but aren’t limited to the arteries close to the trachea, the temple or the inside of either wrist. Once the heart beat is found, count to how many beats are contained within 30 seconds, a stop watch may need to be used to keep track of time. By multiplying this number by 2, one can get the beats per minute. This is how the resting heart rate and the heart rate after exercise will be checked. Before the exercise trials are taken, get an average resting heart rate, go through the procedure described above and do it 3 times and take the average (Nelson, K. and Burpee, D.). It is also crucial to this lab that the process of how to take one’s blood pressure is known. There are two tools needed to measure blood pressure, a sphygmomanometer and a stethoscope. A sphygmomanometer is the cuff that is put around the arm; it has a pressure gauge as well as a bulb to pump up the cuff. The stethoscope is important because it is required to listen to the heartbeat. A typical blood pressure should be somewhere in the range of 120/80, 120 being the systolic pressure and 80 being the diastolic pressure, this is typically how blood pressures are written. The person who is being tested should have their arm resting on a table, palm up and so the upper arm is in line with the heart. The brachial artery is used to find blood pressure; it is located about 3cm above one’s elbow crease. The cuff of the sphygmomanometer should be placed, with the bottom of the cuff over the brachial artery, on the bare arm of the person. The stethoscope should be placed slightly under the cuff, on the brachial artery. After the tester puts the ear tips of the stethoscope in, they can begin. To begin, the tester must pump the cuff up to about the 200mmHg mark, without keeping the cuff inflated for long begin releasing the air pressure at a rate of about 3mmHg/sec. It is important to remain still, because the tester is now listening for the first thump of the heart, which is recorded as the systolic blood pressure. The beats will continue, but will become fainter and fainter. Since the pressure is decreasing, it is allowing for the blood to flow more freely. Once the cuff is no longer interfering with the blood pressure the beating sounds will stop, this is known as the diastolic pressure. Like with heart rate, an initial collection of resting data must be taken. So the process above will be used to find everyone’s blood pressure at rest (Nelson, K. and Burpee, D.). Once these processes are mastered, the exercise data collection can take place. The exercise trials will consist of 30-­‐second pulse counts, which will be calculated after the participant is done with the specific exercise at hand. This lab will use a step exercise and to keep the data impartial, a 33cm high stepping box will be used for people shorter then 5 feet 6 inches and a 40cm high stepping box for people who are taller than 5 feet 6 inches. Each step exercise will go to a rhythm, which will be kept with a metronome. The activity is split into 4 different actions, it is known as a four count activity. The first action is to place one foot on the step, the second count is to bring the other foot up and have both feet on the box, then step down with one leg and then the final count is to step entirely off the box. The steps must be in rhythm with the metronome. The fist trial is a 15 step per minute exercise, which is the same as a 60 count. The person checking the exerciser’s pulse will use the artery next to the trachea, also known as the carotid pulse. The pulse taker will begin exactly 15 seconds after the exercises are done and will count the pulse for 30 seconds. Just like the pulse counter, the person taking the exerciser’s blood pressure will begin 15 seconds after the exercise. The same steps listed above will be used again for the second trial, but instead of 15 steps per minute, trial 2 will consist of 30 steps per minute. 30 steps per minute is equivalent to 120 counts, 4 counts per step. All the data will be recorded in data tables (Nelson, K. and Burpee, D.). Once all the data was collected and the trials completed, the data could now be analyzed. Since this lab focused primarily on the affect gender had on cardiovascular health and other correlations that gender shows, the data had to be organized in a way so that males were one population, making females the other. There were specifically three components being tested, the 30-­‐second pulse count, systolic blood pressure and diastolic blood pressure. Under all these tests are the data collected from the participants at rest and after the two exercise trials. The % differences were found for both the 15 step and 30 step exercises all the data sets using the formula shown in figure 1. 𝐷𝑎𝑡𝑎 𝑓𝑟𝑜𝑚 𝐸𝑥𝑒𝑟𝑐𝑖𝑠𝑒𝑠 − (𝐷𝑎𝑡𝑎 𝑓𝑟𝑜𝑚 𝑅𝑒𝑠𝑡)
×100 (𝐷𝑎𝑡𝑎 𝑓𝑟𝑜𝑚 𝑅𝑒𝑠𝑡) Figure 1. This formula was used to calculate percent differences comparing the individual exercise trials, from the pulse count and blood pressures, to the resting data. Once the percent differences were found, the average was taken. The average was taken from the resting data as well as from the % differences from all the components being tested. Once the average was found, standard deviations were found. The standard deviation, which is the how far values are from the mean, was taken from all the data from the resting and % differences, from all the trials, just like the average. The formula used was the pre-­‐made formula that excel provides, which is =STDEV(number1:numberxx). Once the standard deviation was found, the standard error can be calculated. The standard error shows the uncertainty of the estimate of the mean measurement. The formula used to calculate standard error is shown in figure 2. 𝑆𝑡𝑎𝑛𝑑𝑎𝑟𝑑 𝑑𝑒𝑣𝑖𝑎𝑡𝑖𝑜𝑛
𝑇𝑜𝑡𝑎𝑙 𝐴𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑃𝑎𝑟𝑡𝑖𝑐𝑖𝑝𝑎𝑛𝑡𝑠
Figure 2. This formula was used to calculate the standard error of the various trials. The final analysis of the data was done using a T-­‐test, the purpose of this test is to determine if there is a significant difference between two populations. If the T-­‐test value is below 0.05, the two populations show a significant difference. The formula used for the T-­‐
test was a pre-­‐made formula on excel, the formula was =TTEST(array1, array2, tails, type) (Nelson, K. and Burpee, D.). (Add exceptions/deviations) Results: The tables and figures shown below were collected from individuals taking the Bio 240W class. Table 1: Resting Level Values Pulse count Sys.BP Dias.BP Average SE Males Females Males Females 38.8 39.22727273 1.545612419 0.983916809 126 120.7878788 1.927248223 1.146269952 83.5 79 3.443263075 3.293991316 Table 1. This table displays the average resting values of pulse count, systolic and diastolic blood pressures. The corresponding standard errors were also included. Figure 3: Average Resting Levels 30 Sec Pulse Rate and Pressure Average Pulse Rate, Systolic and Diastolic Bloos Pressure for Different Gendered Individuals at Rest 140 120 100 80 Males 60 Females 40 20 0 Pulse count Sys.BP Dias.BP Figure 3. This graph displays the average resting values of pulse count, systolic and diastolic blood pressures. Table 1 was used to make this graph and the standard errors were used to make the error bars. Table 2: Average Percent Difference in Pulse Count Taken 30 Seconds After Exercises Pulse count 15-­‐steps av. % diff Males Females SE Males Females 11.81360339 17.23296161 5.971656819 3.668855479 30-­‐steps 47.58291739 46.85578384 9.693748175 4.330705244 Table 2. This table displays the average percent differences of pulse count for the 15 and 30 step exercises. The stand errors were also included. Figure 4: Average Percent Difference of Pulse Counts After Exercise Pulse Rate After Exercise 70 Average Percent Difference 60 50 40 Males Females 30 20 10 0 15-­‐steps 30-­‐steps Figure 4. This graph displays the average percent differences of pulse count for the 15 and 30 step exercises. Table 2’s data was used for this graph, along with the standard errors which were used for the error bars. Table 3: Average Percent Difference of Systolic Blood Pressure After Exercises Sys.BP
av. % diff
Males
15-steps
Females
8.371350908 6.536654002
SE
Males
Females
2.472145156
1.532142398
30-steps
21.05729601 15.68344752 3.308246844 1.737278327
Table 3. This table displays the average percent differences of systolic blood pressure for the 15 and 30 step exercises. The standard errors were also included. Figure 5: Average Percent Difference of Systolic Blood Pressure After Exercise Systolic Blood Pressure After Exercise 30 Average Percent Difference 25 20 Males 15 Females 10 5 0 15-­‐steps 30-­‐steps Figure 5. This graph displays the average percent differences of systolic blood pressure for the 15 and 30 step exercises. This graph is based off the data from Table 3, along with the standard errors which were used for the error bars. Table 4: Average Percent Difference of Diastolic Blood Pressure After Exercises Dias.BP 15-­‐steps av. % diff Males Females SE Males Females 3.259156314 3.656520877 4.767092635 3.709041138 30-­‐steps 4.789087131 9.418094265 5.050807428 4.721384772 Table 4. This table displays the average percent differences of diastolic blood pressure for the 15 and 30 step exercises. The standard errors were also included. Figure 6:Average Percent Difference of Diastolic Blood Pressure After Exercise Diastolic Blood Pressure After Exercise 16 14 AveragePercent Difference 12 10 8 Males 6 Females 4 2 0 -­‐2 -­‐4 15-­‐Steps 30-­‐Steps Figure 6. This graph displays the average percent differences of diastolic blood pressure for the 15 and 30 step exercises. This graph is based off the data from Table 4, along with the standard errors which were used for the error bars. Discussion: Both from back research on gender and its relationship with blood pressure along with the data collected from this lab, my previous hypothesis that the systolic and diastolic blood pressures will be lower in women compared to men, is supported based on most of the data and both journal articles. Before any exercise the data showed support for my hypothesis. In figure 3 both the bar graphs, the systolic and diastolic bars, show that women’s systolic and diastolic blood pressures, while at rest, are lower then males. Since in younger adults, as supported in the one article above, will have a lower systolic and diastolic blood pressure, my hypothesis is supported (Oparil 2005). In figure 5, my hypothesis is also supported. For both the 15-­‐step and 30-­‐step exercise, the data shows that females have a lower systolic blood pressure when compared to men. Which like the resting data is supported by the one article. Since women have a lower capability of regulating blood pressure, which was taken from another journal article, they are predicted to have a lower systolic and diastolic blood pressure, as stated in the introduction (Convertino, 1998). Even though figure 6, which was the diastolic bar graph, showed the opposite relationship, the error bars, caused by errors in the data, were so great that the data could still show the relationship that was expected by the hypothesis and articles. This was the only data that didn’t exactly follow previous ideas and claims. Some general trends and observations that can be made are as followed. At rest, the pulse count is low, which is expected since the heart doesn’t have to pump a great amount of oxygen through the body because the body is not in motion and using it up. After the 15-­‐
step exercise, the pulse count showed an increase, with females showing a great increase. The T-­‐test for these values is not significant for either, since they is above 0.05, which is seen in all the data but one. Even thought the females showed a larger increase in the 15-­‐
step exercise, the 30-­‐step exercise showed a slightly higher increase in males. Which would imply that at lower exercise intensities, females have a higher heart rate than males but at higher intensity exercises males have a higher heart rate. In both the systolic and diastolic blood pressure graphs, figures 5 and 6 respectively, an increase is seen from the pressures at rest and an increase can be seen from 15-­‐steps to 30-­‐steps. The problem with both of these figures is that they both have large error bars, especially diastolic blood pressure which even dips into e decrease from the data collected at rest. For both these graphs, the T-­‐test shows no significant difference. There were some sources of error that could explain why the data wasn’t completely accurate. When taking the pulse counts and blood pressures, the methods and materials say to wait 15 seconds and then start the data collection. Setting up to take blood pressure and searching for the pulse take time, which can give various different types of data since they are all taken at different times after the exercises. References: Ann, C. (2010, July 24). About Systolic & Diastolic Blood Pressure During Exercise. Retrieved April 5, 2012, from Livestrong.com: www.livestrong.com/article/183287-­‐about-­‐
systolic-­‐diastolic-­‐blood-­‐pressure-­‐during-­‐exercise/ "Cardiovascular Physiology: The Relationship between Gas Exchange and Cardiac Activity." Edited by Nelson, K. and Burpee, D. Department or Biology, The Pennsylvania State University, University Park, PA. (2012) Convertino, V. A. (1998, August). Gender differences in autonomic functions associated with blood pressure regulation. American Journal of Physiology , R1909-­‐R1920. Jane B. Reece, e. a. (2011). Campbell Biology (Vol. 9). Boston: Benjamin Cummings: imprint of Pearson. National Geographic. (n.d.). Retrieved April 4, 2012, from Neart: science.nationalgeographic.com/science/health-­‐and-­‐human-­‐body/heart-­‐article/ Oparil, Suzanne, and Andrew P. Miller. "Gender and Blood Pressure." The Journal of Clinical Hypertension 7.5 (2005): 300-­‐09. Print.