Effects of Insulation and Antifreeze/Glycerol on Thermoregulation of Simulated Animals Living in Cold Conditions

 

Tested Studies in Laboratory Teaching, 2004, Volume 25

Abstract

The survival of all living organisms depends on their physiological and behavioral adaptations to their environment, especially in extreme conditions. Endothermic animals maintain their dynamic body temperature via internal heat production and appropriate insulation, such as fat and fur. The survival of ectothermic animals living in temperatures considerably below the freezing point of their body fluids depends on unique compounds, such as supercooling agents, glycerol, and glycoprotein. These "antifreeze" compounds found in blood and tissue fluid prevent the fatal formation of ice in their body tissues. To study the thermoregulation mechanisms of endotherms in cold temperatures, 160-ml aluminum cans were filled with 37?C normal saline to simulate endothermic animals' internal environment. The first objective of this study was to determine the effectiveness of fat and/or fur as insulators on thermoregulation at ambient temperatures of 22?C and 8?C. The second objective was to investigate the effectiveness of glycerol, antifreeze, and sodium chloride on thermoregulation of ectothermic animals at freezing ambient temperatures. The results of the experiment demonstrate that fur is a better insulator than fat. However, both fat and fur decrease the fluctuation of internal temperature and assist in maintaining a relative stable internal temperature for a longer period of time compared to the control with no external insulation. The findings support the concept that animals in cold ambient temperatures develop a thicker layer of subcutaneous fat to help them maintain a more stable internal temperature without the expenditure of vast amounts of energy generated by shivering. In the simulation of ectothermic animal's internal environment, various concentrations of glycerol, glucose, sodium chloride, and antifreeze are shown to lower the freezing point. The freezing point depression of the fluids increases linearly with their concentrations. The presence of antifreeze has the greatest effect in preventing the formation of ice under prolonged subzero temperature conditions. Utilizing antifreeze compound in the blood and tissue fluid permits animals to survive and swim in seawater at a temperature of –1.8?C.

Keywords:  freezing point depression

University of Nevada, Las Vegas (2003)