Lecture 17 Flashcards
Bergmann’s Rule
*Larger animals are found in colder environments and smaller animal are found in warmer regions
*larger animals are more efficient at maintaining heat
Allen’s Rule
*Animals adapted to warm climates will have longer limbs and appendages than animals adapted to cold climates
*In hot climates, it is advantageous to have a high surface area to volume ratio
*in cold climate, it is better to have a low surface area to volume ratio
Vasoconstriction
Constriction of blood vessels close to skin surface
*reduce heat loss
Brown Adipose Tissue
Brown adipose tissue (BAT) is a type of fat that helps your body generate heat by burning calories. It’s important for keeping warm, especially in cold conditions. Unlike regular fat (white fat), brown fat has more mitochondria, which produce heat.
Allostatic Responses to Cold Stress
1) Shivering
2) Non-Shivering Thermogenesis: heat that is produced through biological mechanism that are separate from muscle twitching
Non-shivering thermogenesis
Indirect Calorimetry
* a method for calculating a person’s metabolic rate by measuring their oxygen consumption and carbon dioxide production
Acclimatization to Cold Stress
*Lower shivering threshold, faster initiation of NST
*Hunting’s Response: Process of alternating vasoconstriction and vasodilation
*Increase in thyroid hormone production and tissue uptake from circulation
*increase in brown adipose tissue (BAT)
Developmental Adaptation
Developmental adaptation is a change in an organism’s body during its growth that helps it survive in its environment. These changes happen as the organism develops, not in response to immediate stress.
Over time, as people live in colder environments, their bodies can develop more brown adipose tissue (BAT), and BAT thermogenesis becomes a regular process. This helps them generate heat more easily and stay warm. The adaptation happens gradually as part of their development in that environment.
