Special senses - taste and smell Flashcards
What are the 3 types of papillae found on the tongue
Fungiform - mushroom shaped and cover entire surface of tongue
Vallate - Largest, have many taste buds each (8-12), make a V shape at the back of the tongue
Foliate - found laterally on tongue and the most sensitive to taste, numbers decrease with age
What are the 5 basic taste modalities?
Sweet = sugars/alcohol/artificial sweetners
Salty = acids (H+ ions in solution)
Bitter = Alkaloids (quinine/nicotine/caffeine) and Nonalkaloids (aspirin)
Sour = metal ions (inorganic salts); most prominent (saltiest) is NaCL - sodium chloride
Umami = amino acids/glutamate/aspartate (beef, meat, cheese)
what are gustatory hairs
contain receptors for food chemicals (tastants)
once they are activated they depolarize and release NTs (serotonin/ATP) and active the chemical nerve for that taste info
are replaced every 7-10 days; stem cell populations = basal epithelial cells
AKA long microvilli found in gustatory epithelial cells that extend though a taste pore to the surface of the tongue
Do taste receptors adapt quickly? Why or why not
Yes they do, each taste receptor has different thresholds and are most sensitive to bitter in order to protect against the ingestion of toxic substances
The mouth also contains thermoreceptors (hot/cold), mechanoreceptors (smooth/crunchy), nociceptors (spiciness/acidity)
What are the main cranial nerves associated with taste
1) Facial nerve (7) - carries impulses from anterior 2/3 of the tongue
2) Glosspharyngeal (9) - carries impulses from posterior 1/3 of the tongue and the pharynx
3) Vagus (10) - transmits from epiglottis and lower pharynx (very minor though)
Where is the gustatory cortex located
In the insula in the brain
Where can pseudostratified columnar cells be found?
Olfactory epithelium located in the roof of nasal cavity
Why might the olfactory epithelium not be the best spot to catch smells
Because it is so high up when breathing in air, smells end up bypassing the cavity and smell receptors are not activated unless the stimulus is strong enough
think about having to consciously be sniffing something to truly smell it, otherwise most odours go unnoticed unless strong enough
what are olfactory sensory neurons
bipolar neurons with radiating olfactory cilia that are surrounded and cushioned by columnar supporting cells
Where in the nasal cavity might we be more prone to damaging?
Stem cells at the base of epithelium - due to colds or constantly blowing our noses
Why do olfactory neurons have long cilia
The long cilia project from a single apical dendrite and work to increase the SA
Axons of _______________ form the olfactory tract.
mitral cells
How many odorants can a receptor respond to
Each receptor can respond to one or more odorants and each odorant can bind to several different receptor types
However each receptor cell expresses only one type of receptor
Are there pain or temperature receptors in the nasal cavity?
Yes there are, they respond to irritants such as ammonia, hot temperatures (spicy things) and cold temperatures (mint or menthol)
What must happen in order for us to smell a substance?
The substance must be volatile as it enters the nasal cavity
Must be able to dissolve in mucus rich fluid coating the olfactory epithelium in order to have access to the olfactory cilia receptors
