Such a burst of speed may raise the metabolic rate, and thus heat production, by as much as 40 fold. Dissipating such heat loads is difficult, especially in arid environments where water is scarce and an animal needs to avoid losing too much through evaporative cooling. The brain is a part of the body that is particularly sensitive to high temperature.
The rete is a configuration of arteries and veins in a sinus at the base of the brain. Warm blood flowing to the brain travels from the carotid artery into a network of small arteries within the sinus, where it transfers some of its heat to cooler venous blood flowing the opposite direction as it returns from the nasal passages.
The cooled arterial blood then continues toward the brain. A predator like the cheetah must stop running when its body and brain temperature reaches The ability to keep a cool head can thus give the gazelle a survival edge in these predatory pursuits as he can outlast the cheetah who cannot maintain a cooler brain. Counter-current heat exchangers can be found in many organisms in many configurations. While such mechanisms are well known to engineers, a close look at the design of those used by nature may be useful in designing thermal control systems of human habitations.
Male Thompson's gazelle. Ngorongoro Crater, Tanzania. Active myogenic tone was mainly observed in the facial, nasal and angular oculi veins of the camels head. This tone was found to be sensitive to small changes in temperature in the range degrees C.
The facial veins constricted, while the nasal and angular oculi veins relaxed to increasing temperatures. J Cereb Blood Flow Metab. J Appl Physiol. Dietrich WD: The importance of brain temperature in cerebral injury. J Neurotrauma Suppl. Google Scholar. Acta Neuropathol Berl. J Anim Physiol Anim Nutr. Article Google Scholar. Einer-Jensen N, Khorooshi MH: Cooling of the brain through oxygen flushing of the nasal cavities in intubated rats: an alternative model for treatment of brain injury.
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Ann Neurol. Download references. Neurosurgery, Odense University Hospital, Denmark. You can also search for this author in PubMed Google Scholar.
E-mail: n. Reprints and Permissions. Einer-Jensen, N. Acta Vet Scand 42, Download citation. Received : 19 April Accepted : 24 August Published : 31 December Anyone you share the following link with will be able to read this content:.
Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative. Skip to main content. Search all BMC articles Search. Download PDF. They include the amount of:. The amount of blood flowing through the skin capillaries is altered by vasoconstriction and vasodilation. These diagrams show the processes that take place when vasoconstriction and vasodilation occur.
Too hot When we get too hot: Sweat glands in the skin release more sweat. The sweat evaporates , removing heat energy from the skin. Blood vessels leading to the skin capillaries become wider - they dilate - allowing more blood to flow through the skin, and more heat to be lost. Too cold When we get too cold: Muscles contract rapidly - we shiver.
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