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MS2 - Nervous System > Chemosensation > Flashcards

Flashcards in Chemosensation Deck (15):
1

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

neurodegenerative disease

2

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

ageusia; anosmia

3

Which is more common, loss of taste or smell?

Smell

4

Which cranial nerves innervate the tongue?

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

5

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

6

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.

7

The gustatory neurons first synapse on ____________.

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

8

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.

9

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)

10

Strong chemical smells and spices activate the ________ nerve.

trigeminal

11

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

vomeronasal system

12

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

13

List the three types of papillae and their locations.

Fungiform: anterior top
Foliate: sides
Circumvallate: posterior

14

Like the photoreceptors, taste cells also _____________.

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

15

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):