Have you ever jumped in the deep end of the neighborhood pool and wondered how you could do a swan dive and survive, as a terrestrial mammal? Many biologists have asked this question before, and if you have, this post is for you. This exact curiosity led to the discovery of the physiological responses that make up the mammalian dive reflex. It took many in-depth studies of marine mammals, terrestrial mammals, and diving in general to piece together the complicated physiological response that occurs during a dive. A person jumps into the water and two things immediately trigger the dive reflex. To get a physiological response, the inputs are “the voluntary or involuntary arrest of breathing and the stimulation of water touching the face” (Gooden 8). The response happens quicker with colder water. The diving response itself consists of three reflexes. Heart rate decreases, giving the oxygen in the blood more time to be used (Kooyman 353). Breathing stops, which is a response called apnea. Outer blood vessels constrict, leaving more Oxygen stores for vital organs to use. These mechanisms work together to create a response that allows mammals to make the dive, whether it be for fun or for fish. A seal dives after a flounder, and basically the same process occurs. However, seals have adapted as marine mammals and are now far better equipped than us for long dives. Their reflexes operate the same way, with the same three physiological responses keeping them alive enough to chase a salmon once submerged. But, in a diving seal, responses go even further to include “temperature drops in the brain” and “slowing metabolism while promoting survival” (Panneton 286). New information suggests that hypothermia may be the metabolic adaptation used to decrease availability of oxygen in marine mammals (Panneton 286). This theory introduces a new hypothesis to be tested experimentally. The study of the mammalian dive reflex and its limits is far from over, though our understanding of its mechanisms has grown substantially in the past century. Remaining to be determined is exactly how this physiological response can benefit us. Can we manipulate it, to use it in our every day lives? How can it benefit divers? The full capacity of this response is yet to be determined, Works Cited
Gooden, B. A. (1994). Mechanism of the Human Diving Response. Integrative Physiological and Behavioral Science, 29, 6-16. Kooyman, G. L., Castellini, R. W., & Davis, R. W. (1981). Physiology of Diving in Marine Mammals. Annual Review of Physiology, 43, 343-356. Panneton, W. M. (2013). The Mammalian Diving Response: An Enigmatic Reflex to Preserve Life? Physiology, 28, 284-297.
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Julia CoteGeorgia Southern Pre-Vet Student, nature enthusiast, avid movie watcher, animal-lover, and feminist. ArchivesCategories |