1. Olfactory (smell)
Remember: food would taste bland without your sense of smell.
The nerves involved in smelling are linked to the emotional center of the brain.
Smell as a warning mechanism: your sense of smell warns you of dangers such as smoke and poisonous gasses.
Also -- it will enable you to enjoy the full flavor of food and drinks.
Your sense of smell is 10,000 times more sensitive than your sense of taste.
Olfactory Receptors:
You can detect thousands of different smells.
These receptors that sense smells are called olfactory receptors.
They occupy a stamp sized area in the roof of your nasal cavity.
Tiny hairs made of nerve fibers dangles from your olfactory receptors which are covered with a layer of mucus.
Smell is formed by chemicals in the air– and it may dissolve in the mucus then the hairs absorb it and excite your olfactory receptors.

2. So – olfactory receptors are stimulated -- they transmit impulses to your brain – and this pathway is connected to your limbic system which contains our emotional life. This explains why your reactions to smells are usually not neutral - you either like or dislike a smell. Smells can leave long-lasting impressions and are strongly linked to our memories. The scent of mown grass might remind you of a childhood summer holiday and the smell of chocolate chip cookies may make you think of your grandmother who made great cookies. Or 25 years from now -- you may have an everything bagel at a bagel place near your house --- and the smell of the bagel will remind you of our wonderful class at SCU when you got one of those everything bagels. Only the best, fresh ones for you people -- not the deeply discounted, day old bagels. I pay retail for you nice students.