Why Rudolph is a red-nosed reindeer
by Katy Edgington,Science Relief Contributor
Tiny blood vessels essential for delivering oxygen and regulating the temperature of the brain are the reason for Rudolph the reindeer’s legendary red nose, research which appeared in the British Medical Journal this week has revealed.
Although it does not go so far as to explain why Rudolph is alone among Santa Claus’s special herd of flying reindeer in having an especially red and shiny nose, the research does explore the links between human and reindeer nasal microcirculation and shines a guiding light for the sleigh of intensive care specialists, as well as other areas of medicine.
The comparative study was led by Professor Can Ince, a physiologist from the Erasmus Medical Center (Erasmus MC) at Erasmus University Rotterdam in the Netherlands. Before the festivities commence and before Rudolph guides Father Christmas’s sleigh through the night sky onto rooftops all over the world, ScienceOmega.com was able to have a word with Professor Ince about the unravelling of this mystery.
Mammalian noses have a diverse range of functions, including heating, controlling inflammation and transporting fluid for mucus formation. The nasal mucosa also has an important part to play in the uptake of drugs and the body’s response to allergens.
"The principle functions are filtration and humidification," stated Professor Ince. "If we did not have hairs in our noses, our lungs would dry out very quickly and lose all efficiency; inhaled air has to be humidified. Mucus formation is another important aspect of the humidification process."
Professor Ince and his colleagues have been investigating nasal microcirculation in humans in a bid to better understand its functions and morphology. Doing so has been hampered in the past by a dearth of techniques by which to look at the flow of blood inside the nose, in the blood vessels of the mucosa. The knowledge gained could be of particular benefit to the large proportion of ear, nose and throat (ENT) patients suffering from nasal congestion, for example.
Tiny blood vessels essential for delivering oxygen and regulating the temperature of the brain are the reason for Rudolph the reindeer’s legendary red nose, research which appeared in the British Medical Journal this week has revealed.
Although it does not go so far as to explain why Rudolph is alone among Santa Claus’s special herd of flying reindeer in having an especially red and shiny nose, the research does explore the links between human and reindeer nasal microcirculation and shines a guiding light for the sleigh of intensive care specialists, as well as other areas of medicine.
The comparative study was led by Professor Can Ince, a physiologist from the Erasmus Medical Center (Erasmus MC) at Erasmus University Rotterdam in the Netherlands. Before the festivities commence and before Rudolph guides Father Christmas’s sleigh through the night sky onto rooftops all over the world, ScienceOmega.com was able to have a word with Professor Ince about the unravelling of this mystery.
Mammalian noses have a diverse range of functions, including heating, controlling inflammation and transporting fluid for mucus formation. The nasal mucosa also has an important part to play in the uptake of drugs and the body’s response to allergens.
"The principle functions are filtration and humidification," stated Professor Ince. "If we did not have hairs in our noses, our lungs would dry out very quickly and lose all efficiency; inhaled air has to be humidified. Mucus formation is another important aspect of the humidification process."
Professor Ince and his colleagues have been investigating nasal microcirculation in humans in a bid to better understand its functions and morphology. Doing so has been hampered in the past by a dearth of techniques by which to look at the flow of blood inside the nose, in the blood vessels of the mucosa. The knowledge gained could be of particular benefit to the large proportion of ear, nose and throat (ENT) patients suffering from nasal congestion, for example.
"Many people have a loss of vascular reactivity in nasal pathologies," he explained. "It is also useful to know the state of blood flow in patients with polyps and abnormally swollen glands, for example. The techniques for looking at circulation are very limited, but here you can see the microcirculation."
The development of a new instrument to directly visualise nasal microcirculation is helping to provide access for medical practitioners to key information about treatment outcomes and responses, as well as enabling them to diagnose various diseases, as Professor Ince outlined.
"Our research area is actually intensive care medicine; there, microcirculation is now measured using a hand-held video microscope with a light guide that you can put on the surface of tissues," he said. "This device has made a big impact because it has opened up cellular imaging as a diagnostic technique.
"In several areas of medicine we’ve seen that, even when blood pressure and other variables are completely normal, there is a lot of abnormality at the microcirculatory level. It has given an added measure of sensitivity to the measurements, in that sense."
Whilst more or less all mammals share the functions outlined above, reindeer are of particular interest because their noses have an extra duty. The researchers discovered that the vascular density of a reindeer nose is 25 per cent greater than that found in the human nose. They also observed similarities in the hairpin structure of the microvessels in both species, but found that, compared to humans, reindeer have a greater number of glands dispersed throughout the nose. These glands are probably for secreting mucus, which helps maintain the optimum nasal climate in all weather conditions.
The Erasmus MC professor and his colleagues from the Academic Medical Center at the University of Amsterdam collaborated with researchers in the Department of Arctic and Marine Biology of the University of Tromsø, Norway, to study the physiology of reindeer. There, in the Arctic Circle, research is carried out into the way the brain regulates temperature and so the authors made use of the facilities to examine this particular aspect of nasal function.
"When the reindeer exert themselves – by pulling Santa’s sleigh, for example – the amount of energy they need to dissipate is astronomical so their brain has the potential to overheat," Professor Ince continued. "One of the main functions of their nose is as a sort of ventilator to keep the temperature of the brain constant; hence it needs a very special circulation technique."
In the far northern reaches of countries such as Norway, and indeed at the North Pole, reindeer live in conditions where the temperature can be as low as or lower than -40°C. In summer, on the other hand, it can actually get quite hot near the North Pole Their brain, however, has to constantly maintain the normal 37°C temperature in order to continue functioning. The reindeer’s nose is essential to bridging this enormous temperature gap.
"We put the specially trained reindeer on a treadmill and took infrared thermal images to look at the temperature distribution in their heads," Professor Enghild told me. "As the reindeer exercise, their nose becomes very hot and, in fact, turns bright red under the infrared sensor."
Rudolph's nose is not red because he has been drinking the sherry, then, but because it is an integral element of the specially adapted physiology which allows him to do such a wonderful job on Christmas Eve.
Click here to watch BMJ’s short documentary on the research.
Read the full research paper here.
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on Friday, January 04, 2013.
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