Body heat regulation

Q: All of the following body organs are involved in heat regulation of the body except? 

A) heart 
B) liver
C) skin 
D) lungs
E) kidney


Answer: E

During winter season, accidental hypothermia is very common. Beside clinical management of hypothermia, it is important to understand the basic pathophysiology of accidental hypothermia. Body temperature regulation is a balance between heat production and heat loss. Heat is produced by cellular metabolism mostly from the heart and liver. Heat is lost from the body mostly via skin and the lungs. Four methods of heat loss are evaporation, radiation, conduction, and convection. Decrease surrounding temperature increases heat loss. With temperature in the surrounding start to decrease, the hypothalamus stimulates the heat production through shivering and increased thyroid, catecholamine, and adrenal activity. Also, vasoconstriction occurs via 2 methods.

• Sympathetically mediated vasoconstriction, and 
• Peripheral vasoconstriction as a direct response 

All these compensatory mechanisms start to wane as core body temperature reaches  35°C. And once the core body temperature reaches 32°C, metabolism, ventilation, cardiac output, and shivering compensatory mechanisms are lost.

#hypothermia


References:

1. Hanania NA, Zimmerman JL. Accidental hypothermia. Crit Care Clin 1999; 15:235. 
2.Jolly BT, Ghezzi KT. Accidental hypothermia. Emerg Med Clin North Am 1992; 10:311. 
3. Lee-Chiong TL Jr, Stitt JT. Disorders of temperature regulation. Compr Ther 1995; 21:697.