Stress

• Cold

Adaptations

• Biological adaptations
  • • Increased peripheral blood flow
    • Warmer skin temperatures & non-shivering thermo genesis
      due to Brown Adipose Tissue (BAT)
• Genetic adaptation

Changes in Body size and shape are caused due to cold station. Subcutaneous fat in adipose tissue has low thermal conductivity and also its presence reduces surface area. This two factors together help in  heat conservation.

• • • Body Size- Eskimos living in Tundra region of Canada and north pole have bulky body then the presence of subcutaneous fat. Body size and shape play effective role in conservation and production of  heat. What is size in colder regions in pages because it results in Greater mass in comparison to  interior skin area that means less surface area. This large body produces more metabolic rate and less surface area the heat is conserved. Does animals loading man having cold adaptations tend to be large. Bergmann’s rule. 
    • Body shape – adapted human beings also have relatively shorter extremities and Limbs. Shorter extremities reduces body surface area and more heat is conserved in comparison to people having larger extrmities that is Allen  rule.
• Cultural adaptation
  
  • • The nature of clothing, the way of construction of houses, Shelters and use of fire are the most important of all cultural practices used for cold adaptations. 
    • Eskimos use the clothing from caribou straw .
    • Northern siberians use insulated boxes to sleep
    • Diet -high fat diet is norm in cold areas.

Cold adaptation is of three types: adaptation to extreme cold, moderate cold, and night cold. Extreme cold favours short, round persons with short arms and legs, flat faces with fat pads over the sinuses, narrow noses, and a heavier-than-average layer of body fat. These adaptations provide minimum surface area in relation to body mass for minimum heat loss, minimum heat loss in the extremities (which allows manual dexterity during exposure to cold and guards against frostbite), and protection of the lungs and base of the brain against cold air in the nasal passages. Moderate cold favours the tall, stockily built individual with moderate body fat and a narrow nose, for similar reasons. Night cold—often part of a desert environment, where inhabitants must be able to withstand hot, dry daytime conditions as well as cold at night—favours increased metabolic activity to warm the body during sleep.