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Frozen Science.

In his most chilling act yet, magician David Blaine entombed himself in a six-ton block of ice for three days last December. "The stunt was designed to test the limits of human endurance, using only willpower to overcome the pain of freezing cold," boasts the 27-year-old Blaine.

Ice sculptors chiseled the contour of Blaine's body in two giant ice blocks and sealed him shut within the two halves. Technicians kept the frozen tomb below 0 [degrees] C (32 [degrees] F)--the temperature at which water morphs into solid ice. Shirtless, without sleep or food, Blaine stood warding off cold's deadly dangers: hypothermia, a dramatic dip in body temperature, and frostbite, damage or death to skin cells triggered by freezing. Luckily--or magically--Blaine emerged after 62 hours, dazed and confused, but unharmed.

Blaine is hardly the first human to come in from the cold. In 1997, worldclass mountaineer Heidi Howkins was buried alive by an avalanche--an enormous flood of snow --while climbing in the Himalayas. Trapped beneath a blanket of snow, Howkins, like Blaine, survived. Read on to learn more about her harrowing ordeal--and how the body combats freezing to death.

Over the past 16 years Heidi Howkins has climbed the world's highest, most perilous mountains, including Everest and K2. At more than 8,000 meters (5 miles) above sea level, winds can whip up to 161 kilometers (100 miles) per hour, and temperatures can sink to a deadly -96 [degrees] C (-140 [degrees] F). Howkins, 32, thrives on the danger. "When you climb a big mountain you're pushing yourself to the limits of survival," she says. "I actually enjoy that."

Or at least she did until May 9, 1997, when Howkins found herself merely 2,185 m (1.4 mi) from the summit of Earth's third highest peak. Forbidding Mount Kanchenjunga looms 8,586 m (5.3 mi) on the border of Nepal and India.

THRILLS AND CHILLS

Howkins' ascent went smoothly until she reached the base of a massive couloir (deep, icy gorge) angling upward at 70 degrees. She sensed immediate danger: snow and ice piled on slopes steeper than 22 degrees spell prime avalanche terrain. A loud noise--or climber's single misstep--can trigger a slab of snow to thunder down, accumulating masses of snow on the way. Avalanches can reach speeds up to 322 km (200 mi) per hour! (See page 12.) "Chances were nil anyone could reach me in an emergency," Howkins recalls. The nearest hospital: a four-day trek away.

But the summit beckoned her. Howkins, alone, tackled the icy wall with two ice axes and crampons (iron spikes attached to boots). She started to climb--when disaster struck. "I remember hearing a crack and a big roar," she says. Within seconds, walls of snow crumbled on top of her, sending her tumbling down the slope: "I felt like I was being tossed around in the surf."

Smothered in an ocean of ice, she couldn't move or breathe. Then Howkins blacked out. Miraculously, when she came to, she found herself on top of the snow (she suspects a second avalanche shoved her body upward). But her injuries proved serious: "I puked pink stuff, which probably means I had blood and snow in my lungs." She suffered a head gash, shattered eardrum, and dislocated shoulder. But her biggest challenge was to simply stay warm: If she couldn't hike down the slope immediately, Howkins would freeze to death.

BITTER ESCAPE

Even on the coldest mountain, the human body produces heat as billions of cells release energy stored in food--a process called metabolism. Blood vessels shuttle heat to every part of the body. But at high altitudes, the body loses heat fast. "Normally, the atmosphere pushes down on your body and wraps around it like a blanket," explains Dr. Jo Ann Pullen at St. Vincent Medical Center in Los Angeles, Calif. "When the atmosphere is thinner [as in high altitudes], heat escapes your body quicker."

If left exposed to bitter cold, the body--which consists of 50 to 70 percent water--would solidify like the block of ice that entombed Blaine. One reason Howkins survived the chill: she wore heat-trapping clothes, like long underwear made of polypropylene, a synthetic fiber designed to rapidly whisk sweat and moisture from the body. "Water pulls heat from your skin 25 times faster than air," Pullen says. "That can be dangerous for sweating climbers surrounded by snow." Howkins also dressed in layers, which helps trap pockets of warm air around her body (see photo, ANATOMY OF A CLIMBER).

Smart clothes aren't enough to help a mountain climber escape freezing to death. Like all humans, Howkins possesses an internal thermostat called the hypothalamus, a peanut-size gland in the frontal region of the brain. Its job: to thermoregulate, or control core body temperature, at about 37 [degrees] C (98.6 [degrees] F)--regardless of external conditions. When the body gets too cold, the hypothalamus generates more heat by triggering the brain's pituitary gland to secrete hormones (chemical signals) into the blood. The hormones ensure each cell maintains a chemical balance so that the cell becomes neither too hot nor too cold.

COLD TO THE CORE

Although Howkins' core temperature remained stable as she hiked to shelter, if it had dropped by two degrees, her hypothalamus would break down, sending her body into the first stages of hypothermia (see The 3 Stages of Hypothermia). Within 10 to 15 minutes, the body's dipping temperature produces a chemical imbalance in the cells of the brain, heart, lungs, and other vital organs. Result: organs start to malfunction. In response, blood vessels constrict, forcing warm blood in the arms and legs back to the organs. Meanwhile, muscles attempt to generate extra heat by shivering (tiny muscle contractions).

Once a person's temperature falls below 31.1 [degrees] C (88 [degrees] F), shivering stops--the body needs to conserve energy at all cost. The endothermic, or heat-absorbing, chemical reactions that energize cells slow down, causing a sluggish heartbeat, clumsy muscle control, and muddled thinking. "Below 35 [degrees] C, it's very difficult for chemical reactions in your body to take place," says Pullen. "Blood thickens and stops circulating properly."

With a dwindling supply of oxygen-rich blood trickling to the skin, the hands and toes become prime targets for frostbite. Water inside skin cells freezes and expands, bursting open cellular membranes (thin barriers surrounding cells). As a result, burn-like blisters bubble on the skin's surface (see photo below). In severe cases, loss of blood to the outer extremities--fingers, toes, nose--causes tissues to turn black and die a condition called gangrene. A gangrened limb is usually amputated to halt infection.

Fortunately, Howkins was able to avoid both frostbite and hypothermia. "The key was to do everything I could, both mentally and physically, to keep myself warm." With the same extreme determination shown by magician Blaine, Howkins persevered through the pain of her injuries to reach the summit's base, just six days after the avalanche. But Howkins doesn't thank magic. Instead she admits, "I was very, very lucky."

ANATOMY OF A CLIMBER

Mountaineer Heidi Howkins' high-tech gear helps keep her warm on dangerous climbs.

ONE-PIECE GORE-TEX[TM] SUIT

Fabric designed to resist wind, sleet, and snow; wicks moisture away from body.

ICE AX

If Howkins' support rope breaks, she digs an ax into the snow to stop a downward slide.

CRAMPONS

Sharp boot spikes cling to steep slopes and prevent snow from caking on boot bottoms.

SLEEPING PAD

Ridges on light-weight sleeping pad capture small pockets of warm air to help keep the body warm.

SUPER GAITERS

Calf-high socks add an extra layer of insulation and keep snow out of boots.

BLIZZARD-RESISTANT BOOTS

Hard plastic shell protects against harsh weather; removable inner layer increases air circulation to reduce frostbite risk.

The 3 Stages of Hypothermia

When the body's core temperature drops to 32 [degrees] C (95 [degrees] F) or below, hypothermia sets in.

MILD: 34 [degrees] - 35 [degrees] C (93 [degrees] - 95 [degrees] F)

SYMPTOMS:

Body feels chilled, muscles shiver.

TREATMENT:

Seek warm shelter, replace wet clothes with dry clothes; drink hot fluids.

MODERATE: 30 [degrees] - 34 [degrees] C (86 [degrees] - 93 [degrees] F)

SYMPTOMS:

Shivering stops, muscles stiffen, mental confusion.

TREATMENT:

Two-day hospital stay required; torso must be reheated before extremities.

SEVERE: 30 [degrees] C (86 [degrees] F

SYMPTOMS:

Slow pulse and breathing, loss of consciousness, increased risk of heart attack.

TREATMENT:

Emergency medical attention required! Body must reheat slowly.

Frozen Science

[GRAPH OMITTED]

Cross-Curricular Connection

Social Studies: Research an expedition to one of the world's coldest places, like the Antarctic, and write a brief report on the physical challenges the expedition faced.

Did you Know?

* The danger of frostbite increases with wind, especially high winds felt by downhill skiers or mountain climbers.

* Hypothermia can occur even' at relatively mild temperatures if exposure to cold is prolonged.

* Once your core body temperature drops below 95 [degrees] F, the rate at which your brain metabolizes body sugar falls off by 3 to 5 percent every minute.

National Science Education Standards

Grade 5-8: personal health * structure and function in living systems * regulation and behavior

Grade 9-12: personal and community health * natural and human-induced hazards * matter, energy, and organization in living systems

Resources

"As Freezing Persons Recollect the Snow," Outside, January 1997, p.68

K2: One Woman's Quest for the Summit by Heidi Howkins, National Geographic Books, 2001

David Blaine's Frozenin Time Web site: www.davidblaine.com/index2.html

Directions: Circle the number that best fits the sentence.

1. Mountain climbers like Heidi Howkins who scale 8,000-meter-high mountain peaks may withstand winds of up to (10 kilometers, 105 kilometers, 161 kilometers) per hour.

2. Temperatures atop high mountains can dip to (0 [degrees] C, -52 [degrees] C, -96 [degrees] C).

3. Avalanches can reach speeds of up to (100 kin, 322 kin, 453 km) per hour!

4. Water pulls heat from your skin (5, 25, 100) times faster than air.

5. Normal core body temperature is (32 [degrees] C, 35 [degrees] C, 37 [degrees] C).

CHECK FOR UNDERSTANDING, p. TE4 FROZEN SCIENCE

1. 161 kilometers

2. -96 [degrees] C

3. 322 km

4. 25

5. 37 [degrees] C
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Article Details
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Author:DYER, NICOLE
Publication:Science World
Geographic Code:9INDI
Date:Mar 12, 2001
Words:1684
Previous Article:Spill Scare.
Next Article:How an Avalanche Forms.
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