Heart:
Introduction (~500 words, 20 %)
1. Explain in detail how physiologically the cardiovascular and respiratory systems adapt to a short term exercise stimulus. Specifically consider the heart, blood pressure and ventilation. As person starts the short term and high intensity exercise, the SAN fires an action potential that spreads across muscles of atria, leading to atrial contraction. This means that all blood from atria moves down to the ventricles along tricuspid and mitral valves.
Shortly, action potential arrives at purkinje fibres, causing a contraction from the bottom of the heart up the septum. This causes pressure in pulmonary artery and aorta to increase leading to an opening of pulmonary and aortic valves. So blood rushes out of heart down the arteries circulating through the body.
Blood pressure
Red blood cells carry heme group, which helps oxygen to be bind to the red blood cells and be transferred around the body in the cardiovascular system. Despite the great changes in cardiac output, increases in blood pressure during exercise are maintained within relatively smaller limits, as both pulmonary and systemic vascular resistance to blood flow is reduced.
Ventilation
Movement of gasses in and out of the lungs. In the respiratory system, the ventilation is rhythmic and consists of expiration and inspiration, some parts of the brain, such as Medullary rhythmicity area,(expiratory/inspiratory area) regulate the rhythmicity of both processes. Expiration is the process of air movement out of the lungs, while inspiration is the process of air movement into the lungs via the pressure difference. This process allows gas exchange to take place. The air flow goes from regions of high pressure to regions of low pressure, to maintain equilibrium. Following system is used to create relative pressure change in lungs as volume of the lungs can be changed by moving diaphragm down and external intercostal muscle contract and internal intercostal muscles relax causing air to move into the lungs to relative low internal pressure. On the other hand diaphragm moves up and external intercostal muscle relax and internal intercostal muscles contract causing air to move out of the lungs from relative high internal pressure to atmospheric pressure. So if volume is increased, pressure is reduced and inversely.
Before inspiration occurs, the atmospheric and alveolar pressure are equal.However during inspiration, contraction of diaphragm and relaxes
As short term, low/normal intensity exercise tend to be aerobic, there is oxygen being used and ATP and Carbon dioxide given off in mitochondrion during respiration.
2. Define the following terms, and the units for each.
a. Tidal volume (Vt) = the amount of air breathed in and out the lungs in 1 breath (litres)
b. Pulse pressure (PP) = Pulse pressure is the difference between the systolic and diastolic pressure readings (millimeters of mercury – mmHg)
3. Suggest a suitable aim and hypothesis for this experiment.
Aim is to find out the effect of a short term exercise on cardiovascular(pulse pressure) . The hypothesis is that during exercise pulse pressure(between systolic and diastolic pressure) increase and are followed on by a decrease to an original(before exercise) value.
4. Consider the raw data collected during this practical, as provided on Blackboard. Should any of the data be excluded? If any participants are excluded, justify specifically your reason why.
Yes, some of the individuals results were excluded from the data set as there was information missing for them. e.g. 16 individuals had more than one result missing, meaning it would be impossible to see how the exercise effected them from both cardiovascular and respiratory sides.
5. Using excel or a similar programme, produce a single table of means and standard deviation from the raw data, summarising the following respiratory variables by time.
a. Breath rate (BR)
b. Expired O2 (FiO2)
c. Expired CO2 (FeCO2)
d. Volume expired (Ve)
e. Tidal volume (Vt)
6. Draw two figures, properly labelled and captioned, showing mean +/- standard deviation of the following cardiovascular variables
Heart rate (HR) every minute
b. Pulse pressure (PP, in mmHg) prior to, during, and post exercise
7. Describe what each figure shows in words. Included a brief comment on why you think these figures are the most useful manner to understand the results.
Fig 1 shows means and standard deviations of respiratory variables by time, which are efficient manner of understanding and comparing results. For example, means of all participants, sorted by time are easier to read than individual ones if we want to compare them with other factors. The breath rate started off with a decrease from 19.53 to 18.80 between min 1-3. It was followed on with an increase from 18.80 to 29.00 up to min 10. Afterwards, as the exercise has finished, steady decrease was seen down to 19.95 at min 14. Also, an anomalous increase between min 14-15 was recorded (19.95 to 20.15 breath rate). The standard deviation for breath rate recorded was significant and caused overlapping, this meant that the difference in mean breath rates at different times was not statistically significant. In next 4 columns we can see mean Expired % of Oxygen, Expired % Carbon Dioxide FeCo2,Volume Expired(litres/min) (Ve) rate, Tidal Volume(litres) with standard deviations included. They suggest that there was statistically insignificant difference between min 5 and 10, as the standard deviations cause overlapping in all of the cases.
fig 2 shows mean heart rate of group of participants over time. It becomes easier to compare the trend in heart rates across the group. Standard deviations, allow us to see highest and lowest possible values across the group. Highest mean heart rate can be seen at min 10 and lowest at min 3, although the general trend line can be clearly seen, overlapping means that there is no statistical significance between all of the times.
fig 3 indicates pulse pressure during 3 stages of the experiment. We can see that mean pulse pressure increase during exercise. However, as the standard deviations overlap, it shows insignificant change. On the other hand, there i a general increase in the pulse pressure during exercise and a return to original pulse pressure straight after exercise has finished.
Discussion (~1 000 words, 35 %)
8. Do the results collected here meet your hypothesis?
Yes, the data collected proves my hypothesis as the was increased pulse rate followed by a reduction to an original value after the exercise.
9. What (physiologically) controls breath rate? Do you have evidence for this occurring here?
As breathing is considered to be an involuntary and conscious action controlled by respiratory centres located in medulla oblongata*(3). The normal response to any physical activity would be an increased pulse rate, just as seen in table 1. It is followed by a decrease in pulse rate straight after the exercise. Although this data supports the theory, there is a chance that some individuals on the bike were nervous*(1) due to being watched and with a mouthpiece in the month and so naturally increased their breath rate and heart rate because of that. This would then lead to an increase of pulse pressure.
10. Suggest how individual participants exercising on bikes might vary in terms of their cardiac and respiratory responses, and physiologically why these responses may occur.
In the experiment people of different gender, weight and sport activity were used to find the results. This led to a wide spread of standard deviation in breath rate, heart rate and gas consumption/volume meaning that variety of different responses were observed.
The gender of the person in the experiment had a great impact on the results. Males have a higher ratio of muscle mass to body weight*(2) which means there are more muscles in men than in women when they are same weight. During any physical activity muscles are in use, therefore require energy and oxygen to perform action. This means that in men the breath and heart rate as well as the volume of air used should be greater than in women. For example in figure 2 the great spread around error bars meant that not all of the
Some people may be more athletic than others due to their sport activity, meaning they will be more efficient with gas consumption, as well as the lower heart rate, breath rate and greater pulse pressure change. However less active individuals will result in greater pulse pressure, heart rate and breath rate change.
11. Suggest changes to the experimental method that might make the data collected more informative.
Firstly each person that participated should have his/her parameters such as weight, height, age and gender wrote into the participants information. Also there must be some additional information about the diet of the person and physical activity of the person as these could effect cardiovascular side of the results.This would make it easier to analyse why some of the data collected might be lower/higher than expected.
Other change that could be done is the variety of levels of intensity for the activity. As at each level of activity, spectrum of reactions from the organisms can be observed. So by having each participant done at least three levels of difficulty( low, medium, high) and three repeats, we can have more reliable results.
On the other hand, a small sample size of 59 members were taken into account, so any anomalous members should be significant. If bigger sample size is being observed, then the effect of an anomalous result on the whole range of data would be significantly smaller.(4)
12. How did you decide on which resources to include and reference here?
If the resources were peer-reviewed or published in scientific articles, they are suitable for use for referencing.
13. What did you learn about your way of working during an experiment in a group setting, and how might you improve on this in future experiments.
In my group, everyone has managed to take their own role, so that we work efficiently on every aspect of data collection, however next time in order to have an accurate data, these roles should be changed around for each repeat. This is due to lose of concentration on specific job as it gets tiring to do same thing over and over again. This might help to remove misinterpretation while reading off the result.
Referencing & formal scientific writing (10 %)
References:
(1)https://www.ncbi.nlm.nih.gov/pubmed/3877552 – Evans DL. of(• 1985 Dec) (accessed on 17 Nov 2017)
(2)http://work.chron.com/physiological-differences-between-male-female-athletes-20627.html – Andrew Latham (2017) (accessed on 18 Nov 2017)
(3)http://www.msdmanuals.com/en-gb/home/lung-and-airway-disorders/biology-of-the-lungs-and-airways/control-of-breathing – (Noah Lechtzin, MD, MHS, Associate Professor of Medicine and Director, Adult Cystic Fibrosis Program, Johns Hopkins University School of Medicine) (accessed on 17 Nov 2017)
(4) https://sciencing.com/advantages-large-sample-size-7210190.html – Jon Zamboni (25 April 2017)(accessed on 15 Nov 2017)