The wet nose, or rhinarium, is essential for determining the direction of the ai
ID: 31926 • Letter: T
Question
The wet nose, or rhinarium, is essential for determining the direction of the air current containing the smell. Cold receptors in the skin are sensitive to the cooling of the skin by evaporation of the moisture by air currents.
That explains why their noses are wet. Why they're slightly moving them when smelling, like on this video (see the close-up in the second part)? Could this very little movement create enough air currents around the nose to determine what smells are coming from what directions? Or is there another reason?
Explanation / Answer
The dog's ability to smell the world around him and to interpret these odors depends on a complicated chemical sensory system. First of all, it possesses mobile nostrils, that help to determine the direction of the smell. Then comes sniffing, the ability to disrupt the air with a regular pattern of breathing that, through laboratory testing, is structured in a series of 3 to 7 snorts. Most of the sensory organs of the dog's nose, the septal organ, are probably responsible for the outbreak of sniffing behavior.
The air is scented, it passes over a bony structure called "projection sub-ethmoid", that man does not possess, and nasal membranes that cover it. The area above the protrusion is not sweep, when the dog exhales air and it allows olfactory molecules to settle and accumulate.
When a dog breathes normally, air is introduced into the nasal passages, it continues its way to the lungs. The action of smell allows air to remain "at rest" in the nasal passages. The intricate complex surrounds the maxillo-turbinate bones of the skeleton provides that the nasal membranes are capable of creating models of air flows odors that lead content in the air to hit the regions of the olfactory receptors.
The odor molecules disintegrate and are concentrated in the nasal mucus that adheres to the receptor cells. Once the mucus, load odor, adheres to the microscopic hairs of receptor cells, the chemical signal odor turns into an electric signal and is sent to the cerebral cortex and the limbic system, ie, the part of the brain that regulate behaviors feeding, drinking and sex. Small molecules stimulate the olfactory nerve of smell. Big odor molecules stimulate the trigeminal nerve, one of the largest nerves of the skull, and the volatiles of sex hormones probably stimulate the vomeronasal organ, the other part of the anatomy of the dog that does not exist in primates.
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