Nsp Week 3: Smell And Taste (Blair)

Front 1

Where is the olfactory epithelium located?

Back 1

Roof of the nasal cavity in the cribriform plate of the ethmoid bone

Front 2

Which glands produce the thick layer of mucus that lines the nasal cavity?

Back 2

Bowman's gland

Front 3

What is the function of basal cells?

Back 3

1. Supportive cells
2. Consist of stem cells that divide and give rise to new receptor neurons

Front 4

Which cells give rise to new olfactory receptor neurons?

Back 4

Basal cells

Front 5

What is the function of Sustentacular cells?

Back 5

Supportive cells

Front 6

The range of sensitivity to different odorants depends on what factors?

Back 6

Physcial properties, such as lipid solubility, vapor pressure.

Front 7

Describe the transduction of olfactory signals occurring in the olfactory cilia

Back 7

Odorant molecule--> G-protein(olf) --> adenyl cyclase --> cAMP produced --> opens channels allowing Na+ and Ca2+ to enter the cell and depolarize the neuron.

*Ca2+ activates a Cl- channel, allowing Cl- to leave the cell, causing further depolarization

Front 8

How many genes are expressed in a single bipolar neuron?
What does this suggest?

Back 8

Only one gene
*The neuron is sensitive to a limited number of odorants

Front 9

How does the brain interpret smell?

Back 9

The olfactory cortex integrates the responses of many neurons

Front 10

The glomeruli receive input from how many types of odorant receptors?

Back 10

Only one type

Front 11

Which cells do olfactory neuron axons contact in the glomeruli?

Back 11

Mitral and tufted cells

Front 12

Axons of which cells form the efferent output of the olfactory bulb (olfactory tract)?

Back 12

Mitral (mostly) and tufted cells
(these are 2nd order neurons)

Front 13

Axons of which cells form the Olfactory N?

Back 13

Olfactory cells
(bipolar neurons)

Front 14

Most olfactory tract axons pass through which stria to reach the olfactory cortex?

Back 14

Lateral olfactory stria
(no olfactory cells actually course in the medial olfactory stria)

Front 15

Which cortical region is part of the anterior perforated substance?

Back 15

Olfactory tubercle

Front 16

Where is the olfactory cortex (paleocortex) located?

Back 16

Near the uncus, at the anterior end of the parahippocampal gyrus

Front 17

Which 2 cortices are considered the primary olfactory cortex?

Back 17

1. Piriform cortex
2. Periamygdaloid cortex

Front 18

List the cortical regions, in sequence, that receive input from the lateral olfactory stria

Back 18

1. Olfactory tubercle
2. Piriform cortex
3. Periamygdaloid cortex
4. Amygdala
5. Enterohinal cortex

Front 19

What is the first cortex in the temporal lobe that the lateral olfactory stria reach?
Which sulcus forms the lateral border of this region?

Back 19

Piriform cortex

*Rhinal sulcus

Front 20

Olfactory information projects to which nuclei of the amygdala?

Back 20

Corticomedial nuclei

Front 21

Which cortex is in the anterior end of the parahippocampal gyrus?

Back 21

Enterohinal cortex

Front 22

All of the olfactory cortical regions send projections to which 4 areas of the brain?

Back 22

1. Dorsomedial thalamus
2. Lateral hypothalamus ("feeding center")
3. Insula
4. Orbitofrontal cortex

Front 23

Which region of the brain allows us to discriminate and identify odors?

Back 23

Orbitofrontal cortex
(fibers course through uncinate fasciculus)

Front 24

Which cortex allows the integration of smell and taste, resulting in perception of flavor?

Back 24

Orbitofrontal cortex

Front 25

Projections to which area of the brain regulates autonomic responses to smells, such as the sense of hunger?

Back 25

Hypothalamus

Front 26

Projections to which area of the brain allows smells to be committed to memory?

Back 26

Hippocampus

Front 27

What makes the olfactory system unique compared to the other traditional senses?

Back 27

1. 2-neuron arc from receptor to cortex
2. Does not relay through the thalamus before reaching the cortex
3. Does not cross the midline

Front 28

How can head trauma cause anosmia or hyposmia?

Back 28

Due to damage to the cribriform plate w/ shearing of olfactory nerve fibers

Front 29

What are anosmias?

Back 29

Chemosensory deficits
(restricted to a single odorant)

Front 30

How can a meningioma cause anosmia?

Back 30

Meningioma in the floor of the anterior cranial fossa may cause pressure on olfactory bulb or tract

(Seen in Neurofibromatosis Type 2)

Front 31

List some signs of irritating lesions to the lateral olfactory area

Back 31

1. "uncinate fits:" imaginary disagreeable odors (parosmia)
2. Involuntary movements of lips and tongue

Front 32

List the 3 types of papillae on the tongue

Back 32

1. Fungiform
2. Circumvallate (vallate)
3. Foliate (leaf-like)

Front 33

50% of taste buds are found in which papillae?

Back 33

Circumvallate papillae

Front 34

Which papillae are found on the anterior 2/3 of the tongue?

Back 34

Fungiform papillae

Front 35

Which papillae are arranged in a V orientation about 2/3 of the way from the front of the tongue?

How many of these papillae are typically present?

Back 35

Circumvallate papillae
*8 - 12

Front 36

Where are foliate papillae located?

Back 36

Posterolateral margin of the tongue

Front 37

Taste buds in fungiform papillae receive innervation from which cranial nerve?

Back 37

CN VII
(chorda tympani branch)

Front 38

The glossopharyngeal N innervates which taste buds from which areas?

Back 38

1. Circumvallate papillae
2. Foliate papillae
3. Pharynx

Front 39

Taste buds in the palate receive innervation from which cranial nerve?

Back 39

CN VII
(greater superior petrosal branch)

Front 40

Taste buds in the region of the esophagus receive innervation from which cranial nerve?

Back 40

CN X

Front 41

Each taste bud consists of how many taste receptor cells?

Back 41

40 - 60

Front 42

List the 5 primary tastes and where they are generally localized on the tongue.

Back 42

1. Sweet --> tip of tongue
2. Salty --> anterolateral
3. Sour --> posterolateral
4. Bitter --> back of tongue
5. Unami (delicious)

*taste buds are sensitive to multiple tastes, but at different sensitivities

Front 43

Which tastes do CN VII, IX, and X respond best to?

Back 43

CN VII --> sweet and salty
CN IX --> bitter and sour
CN X --> sour

Front 44

What kind of transduction receptors are used to detect the five tastes?

Back 44

Salt and sour --> ion channesl
Sweet, bitter, umami --> G-protein coupled receptors

Front 45

What are the different receptor families utilized by sweet, umami, and bitter receptors?

Back 45

Sweet and umami --> T1R family receptors
(sweet = T1R2, T1R3; umami = T1R1, T1R3)
Bitter --> T2R family receptors

Front 46

What is the ultimate effect of all of the taste receptor mechanisms?

Back 46

Increase intracellular Ca2+, causing the release of neurotransmitters (serotonin, ATP)

Front 47

Where do all the primary afferent fibers signaling taste terminate?

Back 47

Gustatory nucleus
(rostral portion of the nucleus of the solitary tract)

Front 48

Where is the gustatory cortex located?

Back 48

Anterior insula, near the inferior portion of the central sulcus
(adjacent to the somatosensory cortex-- near the tongue portion)

Front 49

Fibers from the gustatory cortex project to which regions of the brain?

Back 49

1. Orbitofrontal cortex (same region that olfactory fibers project; perceive flavors)
2. Amygdala

Front 50

List the steps of the Central taste pathway

Back 50

1. Primary afferents in cranial nerves
2. Gustatory nucleus in the solitary tract
3. Ventroposterior medial nucleus of the thalamus
4. Gustatory cortex (anterior insula)
5. Orbitofrontal cortex
6. Amygdala

Front 51

Term for complete loss of taste?

Is this a common occurrence?

Back 51

Ageusia

*NO. This is rare due to widespread and overlapping innervation.
Ageusia would require bilateral loss of innervation to the orofacial region