The major aims and objectives of the report included the following:
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- To take measurements of actual rates of the heart when it is at the state of resting. The value obtained was divided by the response within a minimum interval of 30 seconds.
- To measure and determine blood pressure by making use of a sphygmomanometer. This activity was carried out five minutes before and after some mild body exercise.
- To evaluate the wave of the heart in terms of contraction and relaxation movements using electrocardiogram (ECG) through electrodes that were attached to the human body.
Results of the experiment
This section illustrates the results that were obtained from each aim stated above.
The first objective in experiment one
Dividing response on the value obtained from the heart rate
From the first experiment that was carried out in the laboratory, it is evident that there is a clear difference between heart rate when it is at rest and when engaged in some form of activity. From table one below, the heart rate when resting was found to be 81bpm. However, the mean speed at which the heart contracted when it was engaged in a diving exercise was 45bpm.
Table One: Average heart rate during resting and after a diving response
The second objective in experiment two
How systolic and diastolic pressures are affected by moderate exercise
According to the figures presented in the second table, the blood pressure recorded when the heart was at rest was 123/75mmHg. Nonetheless, the figure obtained after exercise was higher. The mean systolic pressure of the blood was recorded at 147mmHg after the exercise. On the other hand, the diastolic blood pressure was not significantly affected by the short exercise activity. During rest, the blood pressure was 123/75 mmHg as presented in table 2. In comparison, the average systolic blood pressure after exercising raised dramatically to 147mmHg, while the diastolic blood pressure remained almost constant as seen in the table below.
|Blood Pressure (BP)||Blood Pressure (BP)|
|During Rest||After a short Exercise|
|123 mmHg||75 mmHg||147 mmHg||74mmHg|
The above-average results for the blood pressure of participants (students) were taken within an interval of five minutes.
The third objective in experiment three
The use of an Electrocardiogram (ECG) with electrodes attached to the human body
In the third experiment, it is imperative to note that there are three different types of waves as illustrated in the diagram below. These are the T wave, the complex QRS wave as well as the P wave. From the diagram, it is clear that the P wave is the smallest type of wave with the minimum peak. It is then followed by the complex QRS wave with the highest peak. Finally, the T wave completes the wave train. Although the last wave is relatively smaller in size than the complex QRS wave, it is higher in peak than the P wave. From the figure below, the following calculations can be made:
- The time take between two successive R waves (namely PR) is 15.5 – 14.8 = 0.7 seconds
- In terms of the Heart Rate (HR) and also in relation to the time taken between two successive R waves, the Heart Rate (HR) can be calculated as follows:
Heart Rate (HR) = 60 Seconds divided by time taken between two successive waves (PR) = 60 / 0.7 =85 bpm.
The first part of this discussion seeks to answer the question of how the diving response is activated in human beings. To begin with, it is worth mentioning that there are quite a number of biological factors that influence or activate the diving response among human beings (Hudson, 2005). Some of these factors include the slow rise in blood pressure in the blood arteries, decline in blood flow through the limbs, gradual slowdown of the rate at which the heartbeats, and also the overall tendency to hold down breathing patterns. When bradycardia or slowing down of the heart rate takes place, it is clear evidence that the cardiac pacemaker has indeed experienced intense parasympathetic stimulus. On the other hand, vasoconstriction that is occasioned by intense activities in the sympathetic nerves is the major cause of reduction in the amount of blood that flows through the arteries.
In any case, this kind of response is triggered by two major arterial activities. These
Include forced breathing that is not voluntary in nature (also known as reflex breathing) and also, the presence of water molecules that get in touch with the face.
In addition, the cardioinhibitory, vasomotor and respiratory regions are responsible for mechanisms that are coordinated in the brain. Although there are myriads of factors that can modify the diving response system, the degree of hotness or coldness of water (temperature) is a major determinant. Other factors include emotion and arterial oxygen.
The second part of this discussion attempts to explore how relaxation and contraction of the heart are affected by both diastolic and systolic pressures. Firstly, the contraction of the left ventricle leads to systolic pressure. When the ventricle contracts, it leads to the generation of kinetic energy as a result of a large amount of blood that is pushed into the aorta. According to Marieb and Hoehn (2010), in adults who are healthy, their systolic pressure is supposed to be an average of 120mmHg. This figure is compatible with the data obtained from the experiment. Nonetheless, the blood is prevented from flowing back to the cardiac area during systolic pressure. In the process, the recoiling of the aorta walls takes place so that blood can flow straight into the smaller blood vessels. The latter scenario leads to diastolic pressure because the pressure in the aorta resumes its normal state (Marabotti et al., 2009). This explains why students who participated in the above experiment recorded a diastolic pressure of approximately 75mmHg bearing in mind that a healthy adult human being has a diastolic pressure of about 70-80 mmHg. In addition, the cardiac output or performance is increased by the volume of stroke whereas the heart rate is increased by regular exercises. The aforementioned factors consequently increase blood pressure as can be seen in table 2 above whereby the systolic pressure is increased from 123 mmHg to 147mmHg.
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Finally, the cardiac cycle has three unique stages as can be seen on the EEG waves. As already mentioned, the P wave is the smallest, followed by the T wave and lastly, the QRS wave is the largest (Fitz-Clarke, 2006). When the aorta is depolarized, the P wave is produced. On the other hand, polarized ventricles result in the generation of the RRS waves. However, depolarized ventricles lead to the formation of T waves as shown in the figure above.
Fitz-Clarke, J.R. (2006). Adverse events in competitive breath-hold diving. Undersea Hyperb Med 33 (3), 55–62.
Hudson (2005). Human anatomy and Physiology. Portland: Weston Waltch
Marabotti et al (2009). Cardiac changes induced by immersion and breath-hold diving in humans Journal of Applied Physiology. 106(1), 293-297.
Marieb, E. & Hoehn, K. (2010). Human anatomy and Physiology. New York: Pearson.