Olfactory and Taste B7

Question 1

What type of cells are the olfactory receptors?

Answer 1

Bipolar olfactory receptor neurons with a single thin apical dendrite and a basally located unmyelinated axon

Question 2

Where is the olfactory epithelium localized?

Answer 2

Underneath the cribiform plate on the medial wall of the superior nasal turbinate

Question 3

Odorants, particularly ___________ ones such as musk, cross the mucus by interacting with small proteins called _________________.

Answer 3

hydrophobic

odorant-binding proteins

Question 4

Where is the olfactory cortex?

Answer 4

medial surface of temporal lobe.

near the uncus and hippocampus

Question 5

What is a unique aspect of the olfactory system is what?

Answer 5

olfactory bulb projects directly to the cortex

Question 6

True/False: Anterior olfactory nucleus sends contralateral signal but the rest sends ipsilateral signal

Answer 6

True

Question 7

Question 3: Describe pathway from receptor to primary olfactory cortex or other targets of the olfactory tract.

Answer 7

Olfactory receptor to mitral cell to ipsilateral olfactory cortex and projects to contralateral cortex

Question 8

What is the difference between the olfactory nerve and olfactory tract?

Answer 8

Nerves (fila) are basically the receptors that pass through the cribiform plate and the tract is the portion after the bulb

Question 9

Where is primary olfactory cortex located?

Answer 9

In ventral surface of the brain, adjacent to Uncus

Question 10

This recognizes the other cortexes. You can smell an orange but this tells us it actually is the orange.

Answer 10

Orbitofrontal cortex and insula

Question 11

This tells us feeding behavior… determines our hunger. (smells make us hungry)

Answer 11

Hypothalamus

Question 12

This takes smells and reminds us of something, (how odors can trigger memories)

Answer 12

Hippocampus

Question 13

What bone fracture will sever the olfactory nerve fibers?

Answer 13

Fracture of Ethmoid bone in cribiform plate

Question 14

What other pathological conditions or events can cause loss of smell?

Answer 14

(chief complaint is they will say they can’t taste very well)

• Mostly Nasal polyps…
• Rhinitis or sinusitis can block access of odorants to the olfactory epithelium
• Excessive smoking
• Snorting cocaine
• Age-related declines

Question 15

What type of pathological event can cause olfactory hallucinations?

Answer 15

Perceive smell that doesn’t actually exist

Schizophrenia and Korsakoff psychosis

Question 16

What type of lingual papillae contain taste buds?

Answer 16

Fungiform papillae
Foliate papillae
Circumvallate papillae

Question 17

What is the importance of taste buds located in the soft palate, pharynx, and epiglottis?

Answer 17

Detection of food and suppression of aspiration into trachea

Question 18

4 types of functionally distinct cells in the taste bud

Answer 18

Type 1: mainly perform supportive functions
Type 2: Taste receptor cells; possess Gpcr for bitter, sweet, or umami compounds
Type 3: Synaptic vesicles; cells secrete neurotransmitters
Type 4: Basal cells; progenitor cells

Question 19

What portion of the tongue is innervated by CN VII and IX?

Answer 19

Anterior ⅔ of tongue Facial Nerve mostly through the Chorda Tympani, but also with greater superficial petrosal nerve innervating soft palate
-Posterior ⅓ of tongue is Glossopharyngeal nerve

Question 20

Which nerve carries taste from the epiglottis?

Answer 20

Vagus nerve is small area around the epiglottis

Question 21

Describe path of the chorda tympani?

Answer 21

IPSILATERAL PATHWAY: Cell bodies of facial nerve fibers serving taste are located in the geniculate ganglion. They enter solitary tract and synapse on cells of rostral solitary nucleus…

Question 22

Which nucleus is the “taste nucleus” in the brainstem? Where in the brainstem is it located?

Answer 22

Rostral solitary nucleus

In geniculate ganglion and enter brainstem at pontomedullary junction…. pons

Question 23

Does the taste pathway cross the midline?

Answer 23

NO, ipsilateral

Solitary nucleus to VPM to Cortex

Question 24

What is the clinical term for impaired taste sensation?

Answer 24

Ageusia

- Hypogeusia- decreased taste sensitivity
- Parageusia/dysgeusia: distortions in taste perceptions