Olfaction and gustation

What is olfaction

Smell

What is gustation

taste

What allows for smell

Substances dissolved in fluids of the nasal membranes

What allows for taste

Substances dissolved in saliva

What do chemoreceptors respond to?

Chemicals in solution

What are the six qualities of taste?

Bitterness, sourness, sweetness, saltiness, umami, and fat

What is umami?

Savory taste

What is the stimulus for taste?

Tastants which are associated with specific molecules that activate certain receptors

What causes sweet

Complex organic molecules

What causes salty

sodium ions in solution

What causes sour

Acidic ions in solution, H+ ions

What causes bitter

Complex organic and inorganic molecules

What causes umami

glutamate and ribonucleotide

What is the tonuge covered with

papillae

What are papillae

Bumps of the surface of the tongue

Where are taste buds located

in the papillae

What are the four different kinds of papillae

Fungiform, foliate, circumvallate, and filliform

Fungiform

On the tips and anterior sides of the tongue. Detect differences in the nature of food (ex: temp)

Foliate

Rear sides of the tongue. Contain tastebuds for sour and bitter flavors

Circumvallate

Across the back of the tongue. Most sensitive to the bitter taste

Filliform

Contains no taste buds

Do taste buds live for a long time?

No

There are 3 cranial nerves that innerate the tongue. Where do they project to?

The solitary nucleus of the medulla to the thalamus to the tongue region of the somatosensory cortex

What is the only sensation that communicates ipsilateral?

Taste

Between what two structures is there cross communication of the tongue region of the somatosensory cortex?

The frontal lobe and the basal ganglia (reward pathway)

Where is the olfactory epithelium located

In the nasal cavity (under frontal lobe)

What is the organ of smell?

The olfactory epithelium

What type of cells does the olfactory bulb communicate with?

Mitral cells

What do oder molecules do?

They dissolve in mucous and stimulate G proteins on olfactory receptors (Golf) which causes a chemical reaction

Where do mitral cells send impulses to?

The piriform cortex, frontal area, and the limbic area

What is the piriform cortex

It’s the primary cortical olfaction area

Frontal area

Scent identification

Limbic area

emotional area (fast)

How many odorants can we recognize

10,000

How many different olfactory receptors do we have

339

What are the two main theories for odor detection?

Lock and key theory, and the alternative theory

What is the lock and key theory?

Odorant molecules bind to multiple receptors

What is the alternative theory?

The pattern of activity across several receptors that encodes an odor. Happening in the cortex not the epithelium. More like an association