#peripheral vasoconstriction

[biology-geology-beaches-india]

The Scientific research Notes of S. Sunkavally (years: 2002-2011).

1261-1264.

[currentsinbiology]

Your body’s amazing reaction to water

In 1962, Per Scholander, a Swedish-born researcher working in the United States, gathered a team of volunteers, covered them with electrodes to measure their heart rates, and poked them with needles to draw blood. Scholander had seen the biological functions of Weddell seals reverse in deep water; the seals, he wrote, actually seemed to gain oxygen the longer and deeper they dove. Scholander wondered if water could trigger this effect in humans.

He started the experiment by leading volunteers into an enormous water tank and monitoring their heart rates as they dove down to the bottom of the tank. Water triggered an immediate decrease in heart rate.

Scholander noticed something else: Once his volunteers were underwater, the blood in their bodies began flooding away from their limbs and toward their vital organs. He’d seen the same thing happen in deep-diving seals decades earlier; by shunting blood away from less important areas of the body, the seals were able to keep organs like the brain and heart oxygenated longer, extending the amount of time they could stay submerged. Immersion in water triggered the same mechanism in humans.

This excerpt from DEEP: Life, Death & Amphibious Humans at the Last Frontier on Earth by James Nestor (Houghton Mifflin Harcourt)