A Study On The Mammalian Diving Reflex

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Introduction: The mammalian diving reflex represents a primary physiological mechanism to maximize underwater excursions in air-breathing animals. Traditionally, the oxygen-conserving reflex consists of three metabolic and cardiovascular adjustments: (1) notable bradycardia; (2) selective peripheral vasoconstriction; and (3) increased blood flow to the viscera (Kawakami et al., 1967). Previous studies have observed such a response in birds and mammals, generalizing the considerable reduction of heart rate, or ‘diving bradycardia,’ as indicative of the response (Butler, 1982). The evolutionary success of these diving animals relies partly on the functional significance of reducing metabolic demands to prologue underwater survival. Although…show more content…
Moreover, Gooden (1994) describes apnea as an essential element to the diving reflex; it ensures not only the prevention of water inhalation, but also acts as an energy-saving device through decreasing nerve stimulation to the diaphragm and intercostals. Therefore, heart rate will be monitored under both experimental conditions and compared to the resting rate and apneic-resting rate. As a profound autonomic phenomenon, further establishment of the diving reflex in humans will shed light on the preservation of the reflex and its role in the survival during ‘near-drowning’ experiences. Only by examining the physiological response in humans can we appreciate the evolutionary significance of this innate neural circuitry. Methods: An untrained 22-year-old male human subject was chosen. A PT-104 pulse plethysmograph was wrapped around his dominant (right) index finger. Connected through a IXTA data acquisition unit, heart rate was monitored on LabScribe. The recordings were measured with ten seconds of leeway at the beginning and end to allow baseline pulse recovery. Digital marks labeled the time interval of the described action. First the subject’s heart rate was measured during a resting phase for twenty seconds. He was encouraged to relax and remain inactive in order to confirm an accurate baseline reading. For the apneic condition, the subject repeated this

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