Chemosensation 2 Flashcards Preview

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Flashcards in Chemosensation 2 Deck (31):
1

List the 5 primary taste qualities and for each indicate whether sensory transduction involves ion channels or G-protein coupled receptors

1. Salty or Sour: ion channels (since are ionic stimuli).
2. Sweet, bitter, umami (glutamate): metabotropic receptors, G protein linked (more complex stimuli).

2

All taste buds in the pharynx, extreme posterior tongue, esophagus, and epiglottis are innervated by

vagus nerve

3

3 types of gustatory papillae

1. Fungiform papillae
2. Foliate papillae
3. Circumvallate papllae

4

Fungiform papillae:

1. located in the anterior end of the tongue
2. innervated by the facial nerve.

5

Foliate papillae:

1. on the side of the tongue
2. innervated by the facial nerve.

6

Circumvallate papillae

1. located at the posterior end of the tongue
2. innervated by the glossopharyngeal nerve.

7

Central taste pathway:

1. primary afferents from tongue run in the facial, glossopharyngeal, and vagus nerves.
2. When axons enter the CNS they synapse on second order neurons in the rostral area of the ipsilateral Nucleus of the solitary tract (NST).

8

NST

organized orotopically in the medulla. There is a map of the oral cavity on the nucleus so anterior parts of mouth are anterior in the nucleus.

9

Taste Lemnsicus:

1. 2nd order cells (in rostral portions of NST) send axons bilaterally to the medial part of the ventrobasal thalamus

2. The thalamic neurons then send their axons in to insular cortex.

10

Conscious appreciation of taste:

from pathway to insular cortex

11

Orbitofrontal cortex:

where integration of taste and smell leads to perception of FLAVOR!!!

12

Secondary gustatory cortex is located

in the orbitofrtonal surface

13

Secondary gustatory cortex receives projections from

1. the primary gustatory area located on the interior insula
2. olfactory insula areas.

14

Subconscious taste pathways:

NST also relays taste info to hypothalamus and amygdala for food intake regulation and visceral reactions to ingested foods.

15

NST has reflex connections to

nuclei in the brainstem for
1. gagging (nuc ambiguous),
2. swallowing (nuc ambigusus, hypoglossal nuc.)
3. salivation (sup and inf salivatory nuc).

16

Each odorant stimulates a number of receptors.

1. Info on odor identity is NOT coded by labeled line or localized to a single glomerulus.
2. Odor identity is distributed in wide areas of the glomerular layer so it entails PATTERN RECOGNITION!!!

17

Primary principle of encoding odor quality = .

odor-specific map of glomeruli in olfactory bulb

18

Axons of olfactory neurons cross the_____ and converge on ____.

ethmoid bone

glomeruli

19

glomeruli

1. spherical neuropil structures at the outer layer of the olfactory bulb.
2. 1000 axons from single olfactory neuron make excitatory synaptic connections w/ apical dendrite of 2-25 mitral cells at each glomeruli.

20

Olfactory receptor neurons expressing the same olfactory receptor protein project their axons _____

into the SAME glomerulus.

21

Convergence of axons that stem from receptor neurons w/ same chemical specificity is basis for _____

ability of olfactory system to recognize structurally dissimilar odorants.

22

Olfactory cortex: consists of:

lateral olfactory gyrus and part of the uncus

23

Other major olfactory connections with limbic system:

1. amygdala
2. olfactory tubercle
3. entorhinal cortex.

Gives subconscious regulation of homeostasis, circadian, reproductive and other biological activity patterns.

24

Amygdala + olfactory tubercle are interconnected with

hypothalamus

25

Entorhinal cortex:

feeds into hippocampus, major player in storage and retrieval of MEMORIES!

26

Olfactory cortex is divided into several areas including:

1. the piriform cortex
2. accessory olfactory nucleus
3. olfactory tubercle

27

Piriform cortex projects to:

orbitofrontal cortex

28

Orbitofrontal cortex:

association area for olfactory and taste information, gives us the conscious appreciation of smell!!!

29

Output of olfactory bulb

1. projects directly to cortex, NOT through thalamus

30

axons of output cells from the bulb collect into the

lateral olfactory tract

31

Axons of the olfactory bulb project direction to

1. olfactory cortex
2. portion of amygdala