The Changes of Heart Rate of Students during Human Dive Response when Resting and Submerged
The dive response is known more popularly as a mammalian dive reflex. It is a survival mechanism built into mammal’s bodies, essentially. Over the years, scientists have been determined to find what triggers mammals to have a decreased heart rate when submerged under water allowing them to stay under the water longer when they do not typically live under water.
In this experiment, we tested three different conditions in the dive response to see whether heart rate decreased with each treatment. To characterize the dive response, we measured subjects’ heart rates at rest and with their face submerged under a tub full of room temperature water. After that initial step of the experiment, two more treatments were tested to see whether or not it would affect the dive response; when resting, the subject would be able to breath during the thirty seconds, and when submerged, the subject could move their feet slowly as if they were swimming. The latter treatment experiments were then compared to the first experiment done, where the result was used as a control to the new experiments. The purpose of the experiment was to see if there was a difference between the control and experiment; the experiment being movement and breathing. We found that there was a significant difference between the resting and submerged treatments when there is no movement and breathing; (0.009<0.05; P<0.05). With the breathing experiment; (P=0.18, P<0.05), there is no significant difference between the control and the experiment, and with the movement experiment; (P=0.08; P<0.05); this experiment also showed that there is no significant difference in heart rate when moving ones feet and not moving. We were concluded that movement and breathing does not decrease the heart rate for the dive response, but not moving and not breathing during the resting and submerged treatments does change the heart rate for the dive response.
The human dive response was characterized by breath holding, slowing of the heart rate (diving bradycardia). A number of experiments have been conducted over the years, and have shown that the elements of the dive response and breath holding have reduced heart rate. Scientists have been researching topics related to the dive response in both vertebrates that are know for their diving, like seals, and also species that do not have very much diving abilities like humans. Pasche and Krog (1979) conducted an experiment to see the heart rate of resting seals on land and water without the use of restraints on the seals, in order to compare the observed bradycardia in the animals during apneic periods of the two different environmental conditions. Apneic periods are temporary cessation of breathing. Earlier experiments have use restraints on mammals to determine whether or not heart rate decreased or increased when submerged under water. Pasche and Krog found that even though their results showed a more noticeably slower heart rate when the seals dived compared to when on land, there was not a significant difference on a 5% level. As mentioned before, experiments in the past have used restraints on the animals. Animals were restrained and forcibly submerged under water or subjected to forced breathing conditions. Butler and Woakes (1975) have shown that there is a significant difference in the bradycardia during those forced testing’s compared to the natural unrestrained dives. Butler and Woakes used ducks in their experiment. With knowledge of how other experiments were conducted in the past, it gave us a basic understanding of what we could do to make our own experiment.
In the first part of the experiment, we wanted to characterize the human dive response in terms of the change of heart rate when submerged and not submerged. We predicted that the heart rate would decrease over a time period of 30 seconds...
Cited: Pasche, Avid, and John Krog. "Heart Rate in Resting Seals On Land And In Water." Comparative Biochem and Physiology 674.1 (1980)
Butler P.J. & Woakes A.J. (1975) Changes in heart rate and respiratory frequency associated with natural submersion of ducks. Proc. Physiol. Soc., December 1975. D. 16, 16-17
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