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Anatomically, a nose is a protuberance in vertebrates that houses the nostrils, or nares, which admit and expel air for respiration in conjunction with the mouth. Behind the nose are the olfactorymucosa and the sinuses. Behind the nasal cavity, air next passes through the pharynx, shared with the digestive system, and then into the rest of therespiratory system. In humans, the nose is locatedcentrally on the face; on most othermammals, it is on the upper tip of the snout.[citation needed]
Contents  [hide]  * 1 Air conditioning * 2 Sense of direction * 3 Structure in air-breathingforms * 4 In fish * 5 See also * 6 References * 7 External links |
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[edit]Air conditioning
As an interface between the body and the externalworld, the nose and associated structures frequently perform additional functions concerned with conditioning entering air (for instance, by warming and/or humidifying it, also for flicking if movingand by mostly reclaiming moisture from the air before it is exhaled (as occurs most efficiently in camels). The nose often has inner hairs whose function is to stop unwanted particles from entering thelungs.
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[edit]Sense of direction
The wet nose of dogs is useful for the perception of direction. The sensitive cold receptors in the skin detectthe place where the nose is cooled the most and this is the direction a particular smell that the animal just picked up comes from.[1]
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[edit]Structurein air-breathing forms

The nose of a tapir.
In amphibians and lungfish, the nostrils open into small sacs that, in turn, open into the forward roof of the mouth through the choanae. These sacscontain a small amount of olfactory epithelium, which, in the case of caecilians, also lines a number of neighbouring tentacles. Despite the general similarity in structure to those of amphibians, the...