GA: Taste + Olfaction

Question 1

What is umami taste for?

Answer 1

Amino acids

Question 2

What are odorant receptors?

Answer 2

GPCRs

When they are deploarized, that AP travels to the olfactory bulb

Question 3

How does the smell signal go out?

Answer 3

Olfactory receptro neuron –> through lamina propria –> olfactory fila –> cribiform plate –> olfactory bulb

Question 4

What cells are found in the olfactory glomerular layer?

Answer 4

mitral + tufted cells –> make up the efferent output of the olfactory bulb

Periglomerular cells (small interneurons

Question 5

What are the 5 layers of the olfactory bulb?

Answer 5

Glomerular Layer

External plexiform layer

Mitral cell layer

Granular cell layer –> contains granule cells –> The principal interneuron of the olfactory bulb

Question 6

How do granule cells modulate olfactory bulb activity?

Answer 6

Via an inhibitory feedback loop that decreases activtity of mitral + tufted cells

Question 7

In the olfactory bulb, which cells are inhibitory and which cells are excitatory?

Answer 7

Inhibitory = Periglomerular cell + Granule cell

Excitatory = Mitral + Tufted cells

Question 8

What is the hallmark of the olfactory bulb?

Answer 8

It projects directly to cortex and DOES NOT relay via thalamus

Question 9

What forms the lateral olfactory tract?

Answer 9

Mitral + tufted cells

Question 10

IMPORTANT: the olfactory cortex (on the ventral surface of the telencephalon) includes which areas:

Answer 10

Anterior olfactory nucleus

Olfactory tubercle

Piriform cortex

Anterior cortical amygdaloid nucleus

Periamygdaloid cortex

Lateral entorhinal cortex

PAPA OL(D)

Question 11

The lateral hypothalamus + hippocampus are important for what?

Answer 11

feeding behavior + learning + taste

Question 12

What is anosmia?

Answer 12

Loss of smell

Question 13

What is hyposomia or olfactory hypesthesia?

Answer 13

WHAT YOU HAVE :)

Decreased sensitivity to odorants

-can be from nasal polyps

Question 14

What type of pathway is the peripheral taste pathway?

Answer 14

General visceral afferent

Question 15

How does the peripheral taste pathway work for facial N.?

Answer 15

Facial N (chorda tympani + greater petrosal N.) –> geniculate ganglion –> pontomedullary jxn (via intermediate N. –> solitary tract –> solitary nucleus –> gustatory nucleus (rostral portion)

Question 16

How does the peripheral taste pathway work for the glossopharyngeal N.?

Answer 16

Lingual-tonsillar branch innervates taste buds in papilla –> inferior ganglia (petrosal + nodose) –> gustatory nucleus (rostral portion)

Question 17

How does the peripheral taste pathway for the vagus N. work?

Answer 17

Superior laryngeal N. innervates taste buds of epiglottis –> inferior ganglia (petrosal + nodose) –> gustatory nucleus (rostral portion)

Question 18

What is the hallmark of the central taste pathway?

Answer 18

Pathway is ipsilateral

Question 19

What do taste afferents target?

Answer 19

Rostral (gustatory) nucleus

Question 20

In the central taste pathway, how do 2nd order neurons and 3rd order neurons travel?

Answer 20

2nd = central tegmental tract –> VPMpc

3rd = Post. limb of IC –> frontal operculum + ant. insular cortex (Brodmann area 3b)

Question 21

What pathway is responsible for the discrimitory aspects of taste?

Answer 21

solitary nucleus –> VPMpc –> cortex

Question 22

What happens if you get a lesion of the root of CN 7 (or a tumor in the internal auditory meatus)?

Answer 22

Loss of tast to ant. 2/3 of tongue on Ips. side

Paralysis of Ips. facial muscles

Hyperacusis –> paralysis of stapedius M.

Impaired gland secretion

Question 23

What happens if you damage the distal geniculate ganglion?

Answer 23

Ips. facial paralysis

maybe taste loss

Question 24

A complete loss of taste (rare) =

Answer 24

Ageusia

Question 25

Decreased taste sensitivity =

Answer 25

Hypogeusia

Question 26

Distortions in the perception of taste (ex. from drug use) =

Answer 26

Parageusia (dysgeusia)