Smell

DavidsonAnatomy1.jpg
<http://health.ucsd.edu/specialties/surgery/otolaryngology/nasal/anatomy.htm>.



Comprised of bone and cartilage, the nose separates into two hollow nostrils. The nostrils open up to the hollow sinus spaces in the head. As part of the respiratory system, the nose serves several functions. The nasal passages allow air to flow in and out during normal breathing. As a person inhales, the nose warms and humidifies the air before it gets to the lungs. The lining in the nose has many blood vessels at the surface. The warm blood flowing through the nose helps warm the air. The nose has many small hairs inside the nostrils . These hairs serve to filter the air and remove dirt and particles before they enter the lungs. Sneezing and nose blowing help remove the particles out of the body.
The nose has several physiologic functions. One of these is to serve as a conduit for inspired and expired air. As the air is inspired through the nose it is humidified and warmed by passing over the moist and warm nasal mucosa. This function is greatly enhanced by the turbinates for they increase the surface area available for humidification and warming. The nose is an energy-conscious organ in that expired air is cooled and some of the moisture is recaptured. The functions of warming and humidification require a tremendous blood flow to the nasal mucosa and also place substantial stress on the nasal mucosa.


Gasses We Take In:

Oxygen
21%
Carbon Dioxide
.03%
Nitrogen
78%
Rare Gasses
.97%
Water Vapor
varies

Gasses We Breath Out:

Oxygen
16%
Carbon Dioxide
4%
Nitrogen
78%
Rare Gasses
.97%
Water Vapor
Lots



DavidsonAnatomy2.jpg


Smell is extremely important when it comes to taste. Taste depends on smell, mostly because taste depends on the stimlution of the olfactory receptors by smells. Smell is under the classification of a Chemoreceptor. The reason smell is a chemoreceptor is because it depends on the chemicals in solution.
There is a large amount of olfactory rececptors that are located on the roof of our nasal cavities. Olfactory receptors are receptors that are needed to smell. The more air, such as sniffing, entering the nasal cavities and flowing across these receptors the more intense the sense of smell.
Inside the olfactory receptor, there are neurons with olfactory hairs (or otherwise known as nose hairs with mucus), called olfactory receptor cells. In order for an odor to be distincted, the odor must stimulate the olfactory receptors and send impulses to the olfactory cortex of the brain, through olfactory filaments. Olfactory filaments are what make up the olfactory nerve (which is Cranial Nerve I). Once the odor reaches the brain, the odor can be "interpreted", and is held in the brain. Usually, when you smell a distinct odor you have before, you may recognize it.olfactory!.png
(picture above shows1: Olfactory bulb 2: Mitral cells 3: Bone 4: Nasal epithelium 5: Glomerulus 6: Olfactory receptor cells, http://commons.wikimedia.org/wiki/File:Olfactory_system.svg )




Video explaining how the olfactory pathways work, (http://www.youtube.com/watch?v=pM7H0Wud_Y0&playnext=1&list=PL2B86244A0AA3FF15)



Homeostasis:





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