1. The Chemical Senses…
Smell and taste are sometimes referred to as the chemical senses because they respond to chemical molecules rather than to forms of energy such as light and sound waves.
Smell and taste receptors are located near each other and often interact….as a result, we often have difficulty separating the two sensations.

2. Smelly facts 
5 million or more receptor cells at the top of each nasal cavity.
Humans have million total receptors…bloodhounds 200 million. (No wonder they can find stuff!!!)
Most odors trigger a combination of receptors rather than just one detectible receptor for each odor.
There are roughly 10,000 odors or smells that we can detect as humans. The combinations activate different neuron patterns.

3. More to smell…
Taste and smell processing located near each other in brain…one reason why they interact/complement each other.
Brain circuitry between olfactory areas also connects with areas involved in memory storage….smell can trigger memories.
Identifying scents peaks in early adulthood and decline afterwards.
We associate many odors with memories…

4. How it works….
The mucous membrane at the top of each nostril contains receptor cells that absorb airborne chemical molecules.
The receptor cells communicate neural messages to the olfactory bulb…(remember where that is???)

5. “Smellthing” to remember... (hee hee )
Unlike ALL other bodily sensations, impulses from the olfactory bulb DO NOT go to the thalamus. Instead…
The nerve fibers from the olfactory bulb connect to the brain at the amygdala and then to the hippocampus.
This direct connection to these limbic system structures may explain why smell is capable of triggering such vivid memories and emotions.

6. Sense of Taste (Gustation) and the Tongue…
Our sense of taste is based on our tongue…
The tongue is covered with bumps called papillae
The papillae are covered with taste buds, though tastes buds are also found at the back of the throat.

7. Fun facts about the tongue
Each bump on the top and sides of tongue have 200+ taste buds.
Each taste bud has receptor cells, responding to different molecules.
Taste receptors reproduce themselves every 1-2 weeks…that is why you recover after burning your tongue!
Number of taste buds diminish with age, sensitivity diminishes too.
Smoking and alcohol speed this up too.
Taste is also influenced by our “expectations” of taste too.

8. The truth about taste buds…
5 specialized sensory receptors:
Sweet (energy)
Salty (Sodium…essential for body)
Sour (Potentially toxic acid)
Bitter (Potential poisons)
And the new one…
Umani (means delicious or savory) (Proteins needed to grow and repair tissue)…it’s a meat lover!

9. Taste and survival
Taste can play an important role in helping us to avoid eating or drinking harmful substances…
Paired with smell, it can also play an important role in our enjoyment of food!