Effects of a Simulated Dive on the Heart Rate - Report Example

Effects of a simulated dive on the heart rate and the effects of exercise on the ECG (Author’s name) (Institutional Affiliation) Abstract The purposes of these experiments were to examine the changes in heart rate and peripheral circulation due to simulated dive and the effects of exercise on the ECG. Heart rate, pulse amplitude and changes in leg volume were measured in subjects at rest, during simulated dive and breath hold, while in the second experiment, a student, connected to an ECG machine was made to cycle an exercise bike and the heart rate recorded at specified intervals. The findings were that during the stimulated dive, the heart rate and circulation to the peripherals was reduced. This is due to bradycardia, a physiological adaptation, where blood vessels from the peripherals contract and as a response the heart rate slows down. Exercising caused an increase in the heart rate, as the body tries to keep up with increased demand for oxygen and nutrients, which later went back to normal after resting. The gap between the spatial highest peak of the P wave and the beginning of the QRS complex reduces during exercise while the size of the P wave is increased. The P vectors did not change in direction. Introduction The cardiovascular system is made up of the circulatory system and the heart. This network transports blood to body tissues. The cardiac and vascular system in marine animals and terrestrial animals are different. For terrestrial animals to survive while they are submerged in water for long periods of time, they have developed several physiological and biochemical mechanisms (Brett, 1994). Marine animals can stay submerged for long periods of time by use of stored oxygen, decreased oxygen consumption, use of anaerobic metabolism and use of aquatic respiration for those which can. One way of conserving oxygen while diving, is peripheral vasoconstriction (Campbell et al, 1969a). That way, oxygen is delivered only to organs that need it the most like the heart, brain and adrenal glands. This causes an increase in peripheral resistance and to counteract this pressure, the cardiac output is reduced and hence a decrease in the heart rate. This is referred to as bradycardia. Exercising causes a change in the heart rate, blood pressure, respiration and this data can be used to estimate cardiovascular function and conditioning. (Eisner and Gooden, 1983). The brain stem controls the changes in cardiac and vascular system through nerves, blood vessels and arteries. Bradycardia is as a result of increase in the parasympathetic activity thorough the vagus nerves that inhibit the cardiac pacemaker. Vasoconstriction of the limb is produced by the increased activity of sympathetic nerves supplying the arteries in the calf and forearm (Finley et al., 1979; Fagius & Sundlof, 1986). Bradycardia occurs as a way of conserving the limited amount of oxygen in the body when a person is submerged (Fagius & Sundlof, 1986). The diving response is defined as the typical pattern of cardiac, vascular and respiratory reaction activated by holding ones breath during diving (Eisner & Gooden, 1983). This has been shown to be a method of conserving oxygen in diving animals when they are submerging. In humans, this response is less pronounced quantitatively (Gooden, 1993). Exercising can bring out cardiovascular abnormalities that are not present when at rest. These can be used to assess the function of the cardiovascular system. An isotonic/dynamic exercise, which is the muscular contraction of big muscle groups which is as a result of movement, provides a volume load to the left ventricle. This response is proportional to the amount of exercise (Eisner & Gooden, 1983). An ECG translates the electrical activity in the heart into paper in the form of spikes and dips called waves and is used indirectly to detect myocardial ischemia (Jim et al, 2006). Therefore, the purpose of these experiments were to study the effects of the heart rate, pulse amplitude and peripheral circulation in a simulated dive and the effects of the heart rate and pulse amplitude exercise on the ECG. Methods In the first experiment, a student was to submerge their face in water while the rest of the group members timed and monitored the heart rate and pulse amplitude at specific intervals. In the second experiment, a student, attached to an ECG machine, was made to cycle on an exercise bicycle, while the others monitored the heart rate and pulse amplitude at specific intervals (Laboratory manual). Results Table 1. Heart rate and pulse amplitude during rest and dive simulation Condition Rate (BPM) Amplitude Resting 71.7 0.49 15 seconds into the dive 67.1 0.4 End of the dive 44.4 0.31 30 seconds after recovery 69.6 0.42 The heart rate reduces from 71.7 BPM to 44.4 BPM during the diving simulation. The pulse amplitude also decreased from 0.49 to 0.31. Thirty seconds after the recovery, the heart rate increased to 69.6 BPM and the pulse amplitude increased to 0.42. Table 2. Heart rate and pulse amplitude during breath-hold and after recovery Condition Rate (BPM) Amplitude Resting 68.5 0.42 15 seconds into breath hold 68.2 0.43 End of breath hold 67.7 0.45 30 seconds after recovery 70.3 0.42 The heart rate reduced from 68.5 BPM to 67.7 BPM while the pulse amplitude increased from 0.42 to 0.45. After the recovery, the heart rate increased to 70.3 BPM while the pulse amplitude reduced to 0.42. Table 3. Diving response and peripheral circulation Condition Leg volume Resting -0.21 Dive -0.12 Breath-holding -0.22 Blood circulation to the peripherals reduced from -0.21 to -0.12 during the dive but remained more or less the same when holding ones breath Table 4. ECG during rest and after exercise Measurement Resting 10 sec post exercise 30 sec post exercise 60 sec post exercise 120 sec post exercise Heart rate (BPM) 72 115 96 87 77 Pulse amplitude (mV) 0.51 0.7 0.59 0.53 0.51 P-R interval (s) 0.13 0.13 0.12 0.13 0.13 QRS interval (s) 0.08 0.08 0.09 0.1 0.09 S-T interval (s) 0.2 0.16 0.17 0.2 0.21 T-P interval (s) 0.39 0.19 0.34 0.31 0.37 The ECG results show that: the heart rate increased 10 seconds after exercising from 72 BPM to 115 BPM then later began to decrease gradually to 96 then 87 and finally 77 BPM after 30, 60 and 120 seconds respectively. The pulse amplitude behaves in a similar manner, increasing from 0.51 to 0.7 mV and then gradually decreases through the time intervals. The P-R and the QRS intervals all gradually remain the same at 0.13 and 0.08 respectively. The S-T and T-P intervals decrease from 0.2 to 0.16 and 0.39 to 0.19 respectively after the first 10 seconds of exercising but then increases gradually to the resting value of 0.21 and 0.37 respectively. Discussion The results in table one show a decrease in the heart rate and the amplitudes after a simulated dive. This is a physiological mechanism that the body employs so as to reduce oxygen used in the body also known as bradycardia. Table 2 shows that there was a small change in the heart rate when one holds their breath. The increase in the heart rate is the body’s way of rushing the oxygen deficient blood out of the essential organs while pumping in oxygen rich blood (Brett, 1994). The blood rate however returns to normal after sometime. The results in table 3 show how the peripheral circulation is reduced in a simulated dive but later returns to normal after the dive. Table 4 shows the ECG results at different intervals during the exercise. This was as the objectives, the effects of exercise on the ECG, of the experiment was (Jim et al, 2006). The diving response is defined as the typical pattern of cardiac, vascular and respiratory reaction activated by holding ones breath during diving (Eisner & Gooden, 1983). This has been shown to be a method of conserving oxygen in diving animals when they are submerging. Bradycardia is as a result of increase in the parasympathetic activity thorough the vagus nerves that inhibit the cardiac pacemaker. Vasoconstriction of the limb is produced by the increased activity of sympathetic nerves supplying the arteries in the calf and forearm (Finley et al., 1979; Fagius & Sundlof, 1986). Bradycardia occurs as a way of conserving the limited amount of oxygen in the body when a person is submerged (Fagius & Sundlof, 1986). There are two factors that initiate the dive response. These are the voluntary or involuntary/reflex holding of breathing (Campbell et al., 1969a) and the stimulation of water when it touches the face (Hamilton and Mayo, 1944) as is show in the results in table 1 and 2 where the heart rate reduced from 71.7 BPM to 44.4 BPM during the diving simulation. The pulse amplitude also decreased from 0.49 to 0.31. During the breath holding, the heart rate reduced slightly from 68.5 BPM to 67.7 BPM while the pulse amplitude increased from 0.42 to 0.45 (Eisner & Gooden, 1983). Heart rate increases after the breathing movements resume albeit the arterial blood gas tensions are prevented from changing. This is when the thoracic stretch receptors are stimulated by the feedback information from the brain stem to the respiratory and cardiovascular centers (Fagius & Sundlof, 1986). The contraction of peripheral blood vessel causes and increase in pressure and as a way of stabilising the blood pressure, the heart rate is reduced causing a decrease in the pulse amplitude Fagius & Sundlof, 1986). The heart muscle contract and pump muscle with the aid of electrical systems in the heart. During exercise or stress, there is an increase in the heart activity and through the ECG it is possible to monitor the increase in the electrical activity by measuring the distance between the picks and the distances in between (Jim et al, 2006). The HR increases during exercise as the body tissues require an increased demand of oxygen and other nutrients. The brain, via the sympathetic nervous system, sends signals to the heart to redirect direct blood to the muscles. After exercising, the stress that was in the muscles is reduced and hence through a feedback system from the brain, the HR reduces to the normal body levels. The gap between the spatial utmost of the P peaks and the beginning of the QRS complex reduces during exercise while the magnitude of the P wave increased. The P vectors did not change in direction. This is due to the overload of the right atrial. The mechanisms which may explain the pulse amplitude is the changes in the blood conductivity and the intercardiac blood volumes (Jim et al, 2006). References Brett A. Gooden (1994). Integrative Physiological and Behavioral Science, January-March. Vol. 29, No. 1, 6-16. Campbell, L.B., Gooden, B.A. and Horowitz, J.D. (1969). Mans cardiovascular responses to partial and total immersion. Jornl. Physiol. 202: 239-250. Eisner, R. and Gooden, B.A. (1983). Diving and Asphyxia--A comparative study of animals and man. Cambridge: Cambridge University Press. Fagius, J. and Sundlof, G. (1986). The diving responses in man: Effects on sympathetic activity in skin and muscle nerve fascicles. Journl. Physiol. 377: 429-443. Finley, J.P., Bonet, J.F. and Waxman, M.B. (1979). Autonomic pathways responsible for bradycardia on facial immersion. Journl. Applied Physiol. 47: 1218-1222. Gooden, B.A. (1993). The evolution of asphyxiai defense. Integratire Physiological and Behavioral Science. 28: 317-330. Jim M. H, Siu C. W, Chan A. O, Chan R. H, Lee S. W, Lau C. P. (2006). Prognostic implications of P R segment depression in inferior leads in acute inferior heart attack. Clinical Cardiology. Aug; 29 (8):363-8 Hamilton, W.F. and Mayo, J.P. (1944). Changes observed in the vital capacity when the body is immersed in water. American Journal of Physiology. 141: 51 - 53. Read More

Exercising can bring out cardiovascular abnormalities that are not present when at rest. These can be used to assess the function of the cardiovascular system. An isotonic/dynamic exercise, which is the muscular contraction of big muscle groups which is as a result of movement, provides a volume load to the left ventricle. This response is proportional to the amount of exercise (Eisner & Gooden, 1983). An ECG translates the electrical activity in the heart into paper in the form of spikes and dips called waves and is used indirectly to detect myocardial ischemia (Jim et al, 2006).

Therefore, the purpose of these experiments were to study the effects of the heart rate, pulse amplitude and peripheral circulation in a simulated dive and the effects of the heart rate and pulse amplitude exercise on the ECG. Methods In the first experiment, a student was to submerge their face in water while the rest of the group members timed and monitored the heart rate and pulse amplitude at specific intervals. In the second experiment, a student, attached to an ECG machine, was made to cycle on an exercise bicycle, while the others monitored the heart rate and pulse amplitude at specific intervals (Laboratory manual).

Results Table 1. Heart rate and pulse amplitude during rest and dive simulation Condition Rate (BPM) Amplitude Resting 71.7 0.49 15 seconds into the dive 67.1 0.4 End of the dive 44.4 0.31 30 seconds after recovery 69.6 0.42 The heart rate reduces from 71.7 BPM to 44.4 BPM during the diving simulation. The pulse amplitude also decreased from 0.49 to 0.31. Thirty seconds after the recovery, the heart rate increased to 69.6 BPM and the pulse amplitude increased to 0.42. Table 2. Heart rate and pulse amplitude during breath-hold and after recovery Condition Rate (BPM) Amplitude Resting 68.5 0.42 15 seconds into breath hold 68.2 0.43 End of breath hold 67.7 0.45 30 seconds after recovery 70.3 0.42 The heart rate reduced from 68.

5 BPM to 67.7 BPM while the pulse amplitude increased from 0.42 to 0.45. After the recovery, the heart rate increased to 70.3 BPM while the pulse amplitude reduced to 0.42. Table 3. Diving response and peripheral circulation Condition Leg volume Resting -0.21 Dive -0.12 Breath-holding -0.22 Blood circulation to the peripherals reduced from -0.21 to -0.12 during the dive but remained more or less the same when holding ones breath Table 4. ECG during rest and after exercise Measurement Resting 10 sec post exercise 30 sec post exercise 60 sec post exercise 120 sec post exercise Heart rate (BPM) 72 115 96 87 77 Pulse amplitude (mV) 0.51 0.7 0.59 0.53 0.

51 P-R interval (s) 0.13 0.13 0.12 0.13 0.13 QRS interval (s) 0.08 0.08 0.09 0.1 0.09 S-T interval (s) 0.2 0.16 0.17 0.2 0.21 T-P interval (s) 0.39 0.19 0.34 0.31 0.37 The ECG results show that: the heart rate increased 10 seconds after exercising from 72 BPM to 115 BPM then later began to decrease gradually to 96 then 87 and finally 77 BPM after 30, 60 and 120 seconds respectively. The pulse amplitude behaves in a similar manner, increasing from 0.51 to 0.7 mV and then gradually decreases through the time intervals.

The P-R and the QRS intervals all gradually remain the same at 0.13 and 0.08 respectively. The S-T and T-P intervals decrease from 0.2 to 0.16 and 0.39 to 0.19 respectively after the first 10 seconds of exercising but then increases gradually to the resting value of 0.21 and 0.37 respectively. Discussion The results in table one show a decrease in the heart rate and the amplitudes after a simulated dive. This is a physiological mechanism that the body employs so as to reduce oxygen used in the body also known as bradycardia.

Table 2 shows that there was a small change in the heart rate when one holds their breath. The increase in the heart rate is the body’s way of rushing the oxygen deficient blood out of the essential organs while pumping in oxygen rich blood (Brett, 1994). The blood rate however returns to normal after sometime.

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