Chemical Senses

Question 1

Does olfactory tract have a thalamic relay?

Answer 1

No, goes directly to cortices. Projects to piriform cortex, olfactory tubercle, amygdala, and entorhinal cortex.

Question 2

Structure of olfactory epithelium

Answer 2

Sits below cribiform plate. Basal surface has small unmyelinated axons that transmit information centrally. Apical surface has a single dendritic process that expands into knob from which cilia containing odorant receptors extend into a layer of mucus.

Question 3

Olfactory basal cells

Answer 3

Stem cells that give rise to receptor cells

Question 4

Olfactory sustentacular cells

Answer 4

Provide mechanical support for olfactory receptor cells and secrete mucus.

Question 5

Bowmans glands

Answer 5

Produce mucus

Question 6

Patterning of olfactory epithelium

Answer 6

Four bilaterally symmetric zone that have specific receptor subtypes.

Question 7

Olfactory nerves composed of?

Answer 7

Axons of olfactory receptors that coalesce. each nerve passes through cribiform plate and projects ipsilaterally to olfactory bulb.

Question 8

Olfactory glomeruli

Answer 8

Synaptic target of primary olfactory axons, synapses with mitral cells

Question 9

Mitral cells

Answer 9

Principal projection neurons.

Question 10

Are projections of olfactory bulb ipsilateral?

Answer 10

Mostly, some contralateral input maybe to inhibit other side to localize an odor.

Question 11

Projection to dorsomedial thalamus?

Answer 11

Olfactory guided memory

Question 12

Projection to hippocampus

Answer 12

Olfactory guided memory

Question 13

Projection to insular and orbital cortex

Answer 13

Discrimination and identification of odors (taste integration)

Question 14

Projection to lateral hypothalamus

Answer 14

Feeding behavior

Question 15

Unique attributes of the olfactory system

Answer 15

The somas of the primary afferent neurons occupy the surface epithelium, the axons of primary afferents enter cortex directly, continuous turnover of neurons, pathway is mostly ipsilateral

Question 16

Anosmia

Answer 16

Loss of smell

Question 17

Hyposmia

Answer 17

Decreased sensitivity to odorants

Question 18

Hyperosmia

Answer 18

Increased olfactory acuity

Question 19

Olfactory agnosia

Answer 19

Aware of smell, can’t recall name

Question 20

Parosmia/Dysosmia

Answer 20

Distortion in a smell experience

Question 21

Cacosmia

Answer 21

Formation of repugnant olfactory hallucinations

Question 22

Why does rhinitis/sinusitis affect smell?

Answer 22

Block access to olfactory epithelium, can also cause edema.

Question 23

Raccoon/Panda Eyes

Answer 23

Drainage of venous blood to periorbital sinuses. Sign of skull fracture.

Question 24

Why does aging cause olfactory dysfunction?

Answer 24

Decrease in turnover of new receptor neurons.

Question 25

Epilepsy and olfactory system

Answer 25

Cacosmia before uncal seizures

Question 26

Basic Pathway for Processing Taste Info

Answer 26

CN VII, IX, X project to NST in brainstem, which projects to the VPM of the thalamus, which projects to the insula and frontal cortex (specific interpretation of what we’re eating) then projects to amygdala (emotional response).

Question 27

Where are taste buds distributed?

Answer 27

Along the lateral surfaces of taste papillae throughout the tongue.

Question 28

How are taste buds structured?

Answer 28

Arranged around a taste pore, synapse immediately onto afferent axons.

Question 29

Channels for 5 tastes?

Answer 29

Ion: Salt + sour
GPCR: Sweet bitter and umami

Question 30

Projection of second order neurons from NST to thalamus?

Answer 30

Central tegmental tract

Question 31

Primary gustatory cortex

Answer 31

Insula

Question 32

How do neurons get from VPM to insula?

Answer 32

Through the posterior limb of the internal capsule. This is exclusively ipsilateral.