Chemosensation [3]

Question 1

Nerve that supplies these papillae

• Fungiform
• Circumvallate

Answer 1

Fungiform: VII

Circumvallate: IX

Question 2

Taste buds in the soft palate innervated by?

Taste buds in deep throat?

Answer 2

Superior petrosal branch of the facial n.

Vagus (must be a X out of X)

Question 3

Primary afferents from the tongue run in which nerves? When they enter the CNS, where do they synapse on 2nd order neurons?

Answer 3

VII, IX, X

Nucleus of the solitary tract (NST)

Question 4

From the nucleus of the solitary tract, taste bud axons branch and go to which structure for conscious appreciation of taste.

Answer 4

Bilateral Ventrobasal thalamus (VPMpc)

Question 5

From the nucleus of the solitary tract, taste bud axons branch and go to which structure for subconscious rxn to taste & control of appetite?

Answer 5

Hypothalamus & amygdala

Question 6

NST is seen in which cross section?

Answer 6

Medulla (medial to the frog eyes)

Question 7

What is the purpose of the cilia on the olfactory neuroepithelium

Answer 7

1. Odorants dissolved in mucus interact with olfactory receptor proteins.
2. most of the biochemical machinery necessary to convert chemical info into electrical info is located on the olfactory cilia

Question 8

Olfactory neurons are _____ and send (myelinated or unmyelinated?) axon towards the olfactory bulb as part of CN1?

Answer 8

Bipolar

Unmyelinated

Question 9

In order for odor information to be transmitted to the olfactory bulb, the receptor neuron must do what?

Answer 9

Generate an AP

• biochemical cascade that amplifies transduction event way out in the cilia to ultimately cause sufficient depolarization of the cell body to threshold.
• (thanx to Cl-)

Question 10

What happens to Cl- levels when cAMP gated channels permit influx of Na+ and Ca2+?

Answer 10

Cl- levels in receptor cells are high.

Opening the Cl- channel results in outflow of Cl-, thereby further depolarizing the cell

Question 11

What is special about the relationship between olfactory receptor neurons and the glomerulus?

Answer 11

Olfactory receptor neurons expressing the same olfactory receptor protein project their axons to the same glomerulus.
- This is what allows the olfactory system to recognize different odorants
(odor-related map of glomeruli in the olfactory bulb)

Question 12

Why is the olfactory system unique among the senses?

Answer 12

The output of the olfactory bulb projects directly to the cortex.
(all others project to the thalamus)

Question 13

The olfactory cortex is divided into several areas. where do projections for conscious perception of SMELL end up?

Answer 13

Orbitofrontal cortex