Nasal heat exchange in a northern ungulate, the reindeer (Rangifer tarandus).
When reindeer were exposed to low ambient temperatures, heat and water were recovered from the exhaled air by a nasal counter-current heat exchanger. Measurements of respiratory frequency, minute volume, exhaled air temperature and metabolic rate were made over a range of ambient air temperatures extending from -5.5 degrees C to 27.2 degrees C. At ambient air temperatures less than 10 degrees C the exhaled air temperatures were an average of 21 degrees C less than body temperature. The reduction of the exhaled air temperature at the lowest ambient air temperatures used in this study resulted in the recovery of 75% of the heat added and 80% of the water added to the inspired air on its way to the lungs. The heat and water recovered by the nasal temporal counter-current heat exchanger in reindeer significantly reduced the metabolic cost of survival during cold exposure.
D000818:Animals; D001831:Body Temperature; D001833:Body Temperature Regulation; D001834:Body Water / Q000378:metabolism; D006813:Humidity; D008297:Male; D009666:Nose / Q000502:physiology*; D012053:Reindeer / Q000502:physiology*; D012119:Respiration