The Sense of Smell - Anthea, Hayley & Nicole

The Sense of Smell

Initial Deductions
Our initial beliefs were that our nose detects odor molecules that travel through the air, and little feelers in our nose detect these odors and the molecule fit into little smell centers within our nose. These smell centers then send a message to our brain, which processes the resulting information to the sensation of smell. Our initial deduction is correct, although it is a very simplified version of the process that occurs during the sense of smell.

Detailed Description
The sense of smell depends on tiny sensory receptors called chemoreceptors within the nose that respond to odor molecules. These chemoreceptors are located in a patch of tissue high in the nasal cavity called the olfactory epithelium. This patch of tissue is made up of three types of cells: sensory neurons, basal cells and supporting cells between them.

There are millions of sensory neurons, each of which have tiny filaments (cilia) extending from a handle. This handle is located at the tip of the olfactory neuron and the cilia project from the handle directly into the atmosphere. This is the only part of the brain that projects into the atmosphere. The cilia contain olfactory receptors, which are specialized proteins that bind odor molecules. A large multi-gene family encode for these olfactory receptors. Each receptor has a pocket that is just the right shape to bind either a specific molecule or a group of structurally similar molecules. The interaction of the right molecule with the right receptor causes the receptor to change its shape. This change provides an electrical signal that goes first to the olfactory bulb and then to the areas of the brain that convert the electrical signal into a smell.


Interesting Facts

• The sense of smell plays a vital role in our sense of well-being and quality of life.
• Everyone has his or her own unique odor-identity or “smell fingerprint.
• No two people smell the same odor the same way. In other words, a rose may smell sweeter to some people than to others.
• The average human being is able to recognize approximately 10,000 different odors.
• Our sense of taste is greatly influenced by our sense of smell.
• A larger portion of the brains of animals and fish are devoted to the sense of smell than that of humans.
• Your nose can smell directionally, telling you where an odor originates.
• Your sense of smell is least acute in the morning; our ability to perceive odors increases as the day wears on.
• A woman’s sense of smell is keener than a man’s.

Resources
http://www.senseofsmell.org/feature/smell101/lesson1/01.php
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/O/Olfaction.html