The Race to the South Pole and the Biology of Cold Survival in Cold Environments

Geography and Environmental Conditions of Antarctica

• Discovery Background: Antarctica was the final continent on Earth to be discovered. No human set foot on the continent until $1821$.

• Climatic Extremes:

  • It holds the status of being both the coldest and the driest continent on Earth.

  • Desert Classification: Despite the ice, it is a desert because it receives only a few centimeters of rain per year.

  • Historical Low Temperature: The lowest temperature ever recorded on the planet was $-89.2^{\circ}\text{C}$, recorded in Antarctica.

• Geological Features:

  • Mt Erebus: The world’s southernmost active volcano, located on Ross Island.

  • Volcanic Activity: Mt Erebus has been continuously active since the year $1972$.

The Race to the South Pole (1912)

• The Competitors: The race to be the first human at the South Pole occurred in $1912$ between two primary teams:

  • The British Team: Led by Robert Falcon Scott.

  • The Norwegian Team: Led by Roald Amundsen.

• The Norwegian Expedition (Amundsen):

  • Roald Amundsen: A prolific polar explorer.

  • Achievements: First to reach the South Pole; first undisputed expedition leader to reach the North Pole; first to successfully traverse the Northwest Passage.

  • Fate: Amundsen disappeared in $1928$ while flying a rescue mission at the North Pole; neither the plane nor his body was ever recovered.

• The British Expedition (Scott):

  • Robert Falcon Scott: A Royal Navy officer and explorer who led two Antarctic expeditions.

  • The Terra Nova Expedition ($1910$-$1912$): Unlike Amundsen’s focus on the race itself, Scott’s mission had a significant scientific basis.

  • Tragedy: Scott and four other team members died during the return journey from the South Pole. They perished only $18\,\text{km}$ from a base that contained necessary food supplies.

Temperature Scales and Benchmarks

• Critical Temperature Thresholds (Celsius):

  • Boiling point of water: $100^{\circ}\text{C}$

  • Normal body temperature: $37^{\circ}\text{C}$

  • Threshold for hypothermia: $35^{\circ}\text{C}$

  • Standard room temperature: $20^{\circ}\text{C}$

  • Freezing point of water: $0^{\circ}\text{C}$

  • Average summer temperature in Antarctica: $-20^{\circ}\text{C}$

  • Average winter temperature in Antarctica: $-60^{\circ}\text{C}$

Modeling the Effects of Extreme Cold on the Human Body

• Experimental Materials:

  • $3$ boiling tubes.

  • Thermometer.

  • Stopwatch.

  • $500\,\text{ml}$ beaker.

  • $100\,\text{ml}$ measuring cylinder.

  • Ice and warm water.

  • Marker pen.

• Comparative Cooling Data (Simulation Results):

  • The experiment tracks the cooling of water (simulating body heat) over $10$ minutes in different environments (e.g., air vs. water vs. ice water) for three subjects: Captain Scott, Captain Oates, and Lt. Evans.

  • Initial Temperature for all subjects: $37^{\circ}\text{C}$

  • Captain Scott (Air/Water): Dropped to $28^{\circ}\text{C}$ after $10$ minutes.

  • Captain Oates (Ice/Water): Dropped to $19^{\circ}\text{C}$ after $10$ minutes.

  • Lt. Evans (Ice Water): Dropped to $4^{\circ}\text{C}$ after $10$ minutes.

Biological Mechanisms of Thermoregulation (Cold Response)

• Shivering Mechanism:

  • Skeletal muscles contract rapidly and involuntarily.

  • These contractions require energy produced through the process of respiration.

  • A significant portion of the energy from respiration is released as heat to warm the body.

• Vasoconstriction:

  • Blood vessels leading to the skin capillaries become narrower (constricted).

  • This physiological narrowing reduces blood flow through the skin, thereby conserving heat in the body's core.

  • The shunt vessel dilates to redirect blood away from the surface.

• Piloerection (Skin Hairs):

  • When warm, hairs lie flat.

  • When cold, nerve impulses are sent to the hair erector muscles.

  • The contraction of these muscles causes the hairs to rise, trapping a layer of insulating air next to the skin.

The Body's Step-by-Step Response Sequence to Cold

1. Baseline: Normal body temperature is maintained in the range of $35.6^{\circ}\text{C}$ to $37.8^{\circ}\text{C}$.

2. Environmental Trigger: There is a drop in the external temperature.

3. Physical Change: The body starts to cool.

4. Internal Detection: Blood becomes cooler than the level required in the brain.

5. Hypothalamic Response: A part of the brain called the hypothalamus detects the drop in temperature.

6. Physical Reaction (Shivering): The muscles start to contract and relax rapidly; this is called "shivering" and it generates heat.

7. Physical Reaction (Vasoconstriction): Blood vessels in the skin start to narrow.

8. Heat Conservation: Less blood flows in the surface of the skin; consequently, less heat is radiated from the skin and less heat is lost from the body.

9. Recovery: The temperature of the blood starts to rise.

10. Feedback Loop: The brain detects the rise in temperature and stops the body's defensive response.