A brilliant and absorbing account of the effects of hypothermia:
Your head drops back. The snow crunches softly in your ear. In the minus-35-degree air, your core temperature falls about one degree every 30 to 40 minutes, your body heat leaching out into the soft, enveloping snow. Apathy at 91 degrees. Stupor at 90. You've now crossed the boundary into profound hypothermia. By the time your core temperature has fallen to 88 degrees, your body has abandoned the urge to warm itself by shivering. Your blood is thickening like crankcase oil in a cold engine.
Your oxygen consumption, a measure of your metabolic rate, has fallen by more than a quarter. Your kidneys, however, work overtime to process the fluid overload that occurred when the blood vessels in your extremities constricted and squeezed fluids toward your center.
You feel a powerful urge to urinate, the only thing you feel at all.
By 87 degrees you've lost the ability to recognize a familiar face, should one suddenly appear from the woods. At 86 degrees, your heart, its electrical impulses hampered by chilled nerve tissues, becomes arrhythmic. It now pumps less than two-thirds the normal amount of blood. The lack of oxygen and the slowing metabolism of your brain, meanwhile, begin to trigger visual and auditory hallucinations.
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