Panting Cools Blood

two white reindeer agains a light snowy landscape, one has antlers and is seen with an open mouth

Biological Strategy

Reindeer

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Image: Hans-Jurgen Maler / Unsplash / Some rights reserved

Maintain Homeostasis

When a living system is in homeostasis, it means that internal conditions are stable and relatively constant. For example, a human’s internal temperature is approximately 37 degrees Celsius (98.6 degrees Fahrenheit) unless there’s an illness. The human body maintains this temperature despite external ambient temperature. However, as with all physiological processes, maintaining homeostasis requires communication and coordination. So living systems have ways to detect changes from the norm, mechanisms to cause an adjustment, and negative feedback connections between the two. A desert lizard called the Gila monster offers a good example of maintaining homeostasis. The lizard goes from eating large meals to fasting for extended time periods. To maintain its blood sugar levels at a steady level, when food is scarce, its endocrine system releases a hormone that raises its blood sugar levels.

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Protect From Temperature

Many living systems function best within specific temperature ranges. Temperatures higher or lower than that range can negatively impact a living system’s physiological or chemical processes, and damage its exterior or interior. Living systems must manage high or low temperatures using minimal energy, which often requires controlling responses along incremental temperature changes. To do so, living systems use a variety of strategies, such as avoiding high or low temperatures, removing excess heat, and holding heat in. Insulation is a well-known example of managing low temperatures by retaining heat using thick layers of hair, fur, or feathers to hold warm air next to the skin.

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Mammals

Class Mammalia (“breast”): Bats, cats, whales, horses, humans

Mammals make up less than 1% of all animals on earth, but they include some of the most well-known species. We know first-hand some of the characteristics that make mammals unique, like having hair, being able to sweat, and producing milk through mammary glands. Another critical shared feature is a set of highly-specialized teeth. Unlike sharks or alligators, for example, whose teeth are generally all the same size and shape, mammals have differently shaped teeth in different areas of the jaws to target specific foods or foraging strategies.

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The tongue of the reindeer or caribou cools blood heading to the brain under duress by being high vascularized.

“The reindeer (Rangifer tarandus) is an Arctic animal that has adapted to annual changes of 80°C in ambient temperature by growing a fur of excellent insulation value in the autumn to be shed in the following spring. That together with a reduction of surface temperature caused by vascular changes (Johnsen et al., 1985b) and an efficient nasal heat exchange mechanism (Blix and Johnsen, 1983) result in a 30°C reduction in lower critical temperature from summer to winter (Nilssen et al., 1984a). The animal, so equipped to withstand cold, consequently has few avenues of heat loss in winter and runs the risk of hyperthermia during exercise when metabolic heat production rises rapidly with running speed (Nilssen et al., 1984b)…We have observed that moderately heat-stressed reindeer pant, first with the mouth closed, but, under severe heat stress, they resort to open-mouth panting (OMP) to dissipate heat from their big and richly vascularized tongue…We propose that reindeer regulate body and, particularly, brain temperature under heavy heat loads by a combination of panting, at first through the nose, but later, when the heat load and the minute volume requirements increase due to exercise, primarily through the mouth and that they eventually resort to selective brain cooling.” (Blix et al. 2011:3850,3855)

Last Updated September 14, 2016

References

Journal article

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