How does the seal maintain oxygen when diving?

Scientists have discovered that seals are trembling from the cold when exposed to cold air but do not feel the same when diving in icy waters. And they believe this has allowed seals to dive underwater to maintain oxygen and minimize brain damage that can occur during long dives.

Port seals

Scientists presented this study at the American Physiological Society conference with the theme " Relative Physiology 2006: Integrating with Diversity " in Virginia Beach from October 8 to 11 They are scientists: Arnoldus Schytte Blix, Petter H. Kvadsheim and Lars P. Folkow from Tromsø University, located in the far north of Tromsø, Sweden.

The study provides a deep understanding of how seals allow their bodies to become cool (hypothermia) during diving, which may be for them to better deal with hypoxia (reduction). blood oxygen). Researching hypothermia and hypoxia is important because these are issues that affect people in many cases.

For example, Folkows explained, people often ask doctors to treat people with sudden hypothermia, such as falling into the ocean or getting lost in the winter. In addition, every year several hundred thousand people are killed or injured without being able to recover after a temporary cardiac arrest, stroke or respiratory disorder. Enough to supply the brain.

Folkow will present a second study on hypoxia in some birds when they dive at the conference. The study called " The ability to withstand oxygen deficiency in the brain in birds and mammals when diving" studies how seals and birds when diving maintain the function of brain cells when The body faces hypoxia. The study was conducted by Folkow scientist, Stian Ludvigsen and Blix of the University of Tromsø along with scientist Jan-Marino Ramirez of the University of Chicago.

Cold tremors are an unconditional reflex , when muscle contractions cause the body to warm up. Mammals and birds are " programmed " in a physiological way that will tremble when the body temperature falls below a certain " preset " level.

The study found that, when breathing air, seals also trembled because of the cold like other animals. But when they dive into the water in icy water, this tremor reflex is "turned off".

Seals are cold (Photo: sawf.org)

Folkow said, by " turning off " the reflexes of cold tremors, seals allow its body temperature to drop to achieve the benefits of hypothermia - low metabolism and demand. oxygen reduced. And so, their diving time is extended.

The experiment took place in a water tank, where seals performed a lot of diving in cold water of 2-3 ° C. Scientists recorded tremor, heart rate, brain temperature and Rectal temperature of seals when they are on shore and when they are diving.

The results showed that seals on the shore were trembling because of the cold, but when they dived underwater, they stopped or nearly stopped trembling even though their bodies still felt cold. When they dive, their heart rate, brain temperature and rectal temperature decrease, but when they return to the shore, they almost immediately shiver from the cold.

Folkow said seals are able to store significant amounts of oxygen in the blood and muscles - four times more than humans - and the cold-free process will maintain the oxygen needed for muscle and blood. By lowering the body's temperature, they slow down metabolism and reduce oxygen demand. In addition, because the shivering process itself requires oxygen to be supplied, the process of not shivering during diving will be a beneficial process for maintaining oxygen.

Scientists also discovered that, in addition to slowing down metabolic processes and generally reducing the need for oxygen, the brains' brains can also tolerate about 3 ° C while diving. Scientist Folwok explained, the colder the brain requires less energy and oxygen and thus reduces the risk of injury when hypoxia is reduced.

Seals are swimming (Photo: cableone.net)

However, seals have this physiological adaptation only if necessary. Research has found that seals can dive more than 1,000 meters and more than an hour. However, the time they dive is often shorter than their maximum capacity, and only occasionally do they take long dives. By limiting the dive time, seals maintain oxygen metabolism, preventing lactate accumulation from occurring when the body faces an insufficient amount of oxygen and they need only a little time. to regain strength. Folkow also said seals regularly use 80-90% of their time to dive underwater.

Wild seals occasionally dive for so long that they use almost all of the oxygen they have, but they recover very quickly thanks to this special adaptive mechanism. But humans cannot tolerate oxygen levels almost as low as seals can withstand.

" Somehow, seals can withstand better hypoxia than we do, but we don't know why, " said Folkow.

He said that studying how seals deal with hypoxia may one day help us know how to treat people with severe hypoxia, although those techniques can It is still very long to implement in the future.