human adaptation to cold exposure
TRANSCRIPT
Human physiological adaptations to acute cold exposure
David BartonOctober 2, 2014University of Pittsburgh School of Medicine
Temp Regulation
Hammel et al., 1959
Sleep at 5 °C
“Although certain features of this sleeping chamber were objectionable to the natives it proved to be entirely adequate for maintaining a suitable cold exposure.”
Balance of heat gain/loss
Brooks et al., 2005
Radiative heat lossRespirationInsensible water lossUrination
Behavioral adaptations
• Prevent physiological adaptation from needing to occur (usually)
Clothing
FireShelter
ClothingBody
Insulative air pocket
Thompson-Torgerson et al., 2007
Tloc, local skin temperature.
Skin
blo
od fl
ow
Cutaneous vasoconstriction
Infrared scan of the palmar hand surface. Blue, 43° C (109.4° F); red, 68° C (154.4° F). A, At room temperature. B, After 5 minutes in a cold room, with evidence of vasoconstriction.
Auerbach, Wilderness Medicine
Cui et al., 2005Skin suit with 34 or 16 °C water
Cardiac output (CO) = Stroke volume + Heart rate
Wagner and Horvath, 1985
Cold-induced diuresis
Budd and Warhaft, 1966
Segar and Moore, 1968
*Renal blood flow decreases 50% at 27-30 °C
Cold-induced cutaneous vasoconstriction is mediated by Rho kinase in vivo in human skin
Tloc, local skin temperature.
Skin
blo
od fl
ow
Thompson-Torgerson et al., 2007
Effect of cooling (to 28°C) on Rho activity in human cultured dermal arteriolar VSM cells.
Bailey et al., 2004
Brown-Adipose-Tissue Activity as Assessed by PET–CT with 18F-FDG.
van Marken Lichtenbelt WD et al. N Engl J Med 2009;360:1500-1508.
Metabolic energy sources•From fats
•Also from usual sources:▫Carbohydrates, especially glycogen stores▫Protein
•Can cause hypoglycemia decompensation
Havel and Goldfien, 1959
Special considerations
•Some groups cannot adapt as well▫Age extremes▫Disease states▫Alcohol/drugs
•Risk factors for death from accidental hypothermia: ethanol use, homelessness, psychiatric disease, and older ageCDC, 2005
ReferencesBrooks GA, Fahey TD, and Baldwin KM. Exercise physiology: human bioenergetics and its applications. New York:
McGraw-Hill, 2005.Budd GM, and Warhaft N. Body temperature, shivering, blood pressure and heart rate during a standard cold stress in
Australia and Antarctica. J Physiol 186: 216-232, 1966.Cannon B, and Nedergaard J. Nonshivering thermogenesis and its adequate measurement in metabolic studies. J Exp
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Am J Physiol Endocrinol Metab 291: E350-357, 2006.Hammel HT, Elsner RW, Le Messurier DH, Andersen HT, and Milan FA. Thermal and metabolic responses of the
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Segar WE, and Moore WW. The regulation of antidiuretic hormone release in man: I. Effects of change in position and ambient temperature on blood ADH levels. J Clin Invest 47: 2143-2151, 1968.
Thompson-Torgerson CS, Holowatz LA, Flavahan NA, and Kenney WL. Cold-induced cutaneous vasoconstriction is mediated by Rho kinase in vivo in human skin. Am J Physiol Heart Circ Physiol 292: H1700-1705, 2007.
Wagner JA, and Horvath SM. Cardiovascular reactions to cold exposures differ with age and gender. J Appl Physiol 58: 187-192, 1985.
Young AJ, Muza SR, Sawka MN, Gonzalez RR, and Pandolf KB. Human thermoregulatory responses to cold air are altered by repeated cold water immersion. J Appl Physiol 60: 1542-1548, 1986.