Chemosensation Flashcards Preview

MS2 - Nervous System > Chemosensation > Flashcards

Flashcards in Chemosensation Deck (15):

In a subset of people, loss of smell is a symptom of _____________.

neurodegenerative disease


Loss of taste is called _____________. Loss of smell is _________.

ageusia; anosmia


Which is more common, loss of taste or smell?



Which cranial nerves innervate the tongue?

Anterior 2/3: facial (VII)
Posterior 1/3: glossopharyngeal (IX)
Larynx: vagus (X)


There are five tastes that we can sense. List them and give the type of channel that mediates their signals.

Sour: ion
Salty: ion
Sweet: GPCR
Bitter: GPCR
Umami: GPCR


Describe the mechanism of the GPCR receptors.

Upon binding a ligand, the beta-gamma unite activates phospholipase which activates IP3; this releases sarcoplasmic calcium that opens sodium channels (TrpM5) and leads to depolarization.


The gustatory neurons first synapse on ____________.

the solitary nucleus (upper-mid medulla), which projects axons to the VPM in the thalamus


After a ligand binds to an olfactory receptor, what happens?

A GPCR second-messenger cascade (starting with G-alpha) leads to an increase in cAMP; the increased cAMP binds to calcium channels, allowing in a small amount of calcium. Calcium bind to chloride channels and the outflow of chloride depolarizes the cell.


The olfactory tracts lead to what gyri?

The piriform gyri of the medial temporal lobes and thence to the orbitofrontal (conscious smell)

The entorhinal cortex of the hippocampus (memory)

Amygdala/hypothalamus (visceral reaction)


Strong chemical smells and spices activate the ________ nerve.



The pheromone-sensing organ present in many animals is called the _____________.

vomeronasal system


What are the three kinds of chemosensory cells in the body?

Olfactory: bipolar neurons
Gustatory: modified epithelium that synapses on ganglion cells
Chemesthesis: free nerve ending of trigeminal ganglion


List the three types of papillae and their locations.

Fungiform: anterior top
Foliate: sides
Circumvallate: posterior


Like the photoreceptors, taste cells also _____________.

fire in response to multiple sensations (integrating them to avoid hypersensitivity)


The primary way of processing odor quality is through ______________.

glumerular (little bulbs on the other side of the ethmoid bones) integration of odors

Decks in MS2 - Nervous System Class (111):