Lecture 15: Olfaction and Taste

Question 1

Animals with well developed olfactory system are referred to as _____

Humans, by contrast, are ___ and rely less on their sense of smell

Answer 1

Animals = macroscopic
Humans = microscopic

Question 2

True or False: Olfaction is important for memories, emotions, sexual
activities and TASTE

Answer 2

True

Question 3

____ (loss of sense of smell) impairs taste

Answer 3

Anosmia

Question 4

True or False: The olfactory mucosa is located
in the lateral/medial part of
nasal cavity

Answer 4

False - superior/posterior

Question 5

True or False: The olfactory mucosa is made up of cuboidal epithelium layer and is surrounded by neuroreceptors

Answer 5

False - consists of COLUMNAR epithelial layer

Question 6

True or False: Olfactory receptors communicate
with the external environment

Answer 6

True

Question 7

____ are the only neurons that communicate with the external environment and undergo constant replacement

Answer 7

Olfactory neuroreceptors

Question 8

Basal cells near the lamina propria undergo differentiation and develop into olfactory neuroreceptors ever ____

Answer 8

5-8 weeks

Question 9

True or False: The bipolar olfactory neurons have several dendrites that project toward apical mucosa

Answer 9

False - have one dendrite that projects toward apical mucosa

Question 10

True or False: Myelinated axons of the bipolar neurons constitutes the olfactory nerve

Answer 10

False - unmyelinated axons

Question 11

How do olfactory nerve pass from the nasal cavity to the interior of the braincase? Where does it terminate?

Answer 11

Foramina (in cribiform plate of ethmoid bone)

Terminates in olfactory bulbs

Question 12

Which of the following has receptors for odorants?
A. Foramina
B. Olfactory neuroreceptors
C. Cilia

Answer 12

C. Cilia

Question 13

True or False: Density of odorant
receptors is higher in
macrosmatic animals

Answer 13

True

Question 14

Answer 14

Question 15

What is the first processing
station for olfactory info?

Answer 15

Olfactory bulb

Question 16

Olfactory bulb contains 2nd order neurons, which are known as ___ cells

Answer 16

mitral cells

Question 17

Which of the following forms the
olfactory tract?
A. Mitral axons
B. Olfactory axons
C. Cilia axons

Answer 17

A. Mitral axons

Question 18

Where are mitral cells found?

Answer 18

Olfactory bulb

Question 19

True or False: Olfactory receptors are activated
by specific odorant molecules

Answer 19

True

Question 20

Answer 20

Question 21

____: Prominent fiber tracts from the olfactory bulbs, which course towards the ANTERIOR PERFORATED SUBSTANCE

Answer 21

Olfactory Tract

Question 22

At the anterior perforated substance, the olfactory tract splits into two striate:
1.
2.

Answer 22

Medial Olfactory Stria
Lateral Olfactory Stria

Question 23

True or False: Lateral Olfactory Stria project to SEPTAL areas

Answer 23

False - Medial Olfactory Stria project to SEPTAL areas

Question 24

Medial olfactory stria fibers
project to which four SEPTAL areas?

Answer 24

1. Thalamus (DMN)
2. Hypothalamus
3. Hippocampus
4. Upper Brainstem

Question 25

True or False: Primitive responses to olfaction are associated with Medial Olfactory Stria while the Lateral Olfactory Stria is associated with learned behaviors of olfaction

Answer 25

True

Question 26

True or False: The lateral olfactory stria contains majority of olfactory tract fibers

Answer 26

True

Question 27

Which two areas does the lateral olfactory stria carry information to?

Answer 27

1. Olfactory cortices 2. Areas surrounding amygdala

Question 28

Olfactory cortices are collectively known as ____ cortex

Answer 28

piriform cortex

Question 29

Compare and contrast the Primary Olfactory Cortex (AKA prepiriform) to the Olfactory Association Cortex (AKA entorhinal)

Answer 29

Olfactory Association Cortex (AKA entorhinal) - Fibers project to hippocampus - Anterior part of parahippocampal gyrus Primary Olfactory Cortex (AKA prepiriform) - Lateral olfactory area - Projects to amygdala and association cortex

Question 30

True or False: Olfactory pathways ARE required to relay in the thalamus

Answer 30

False - they are NOT

Question 31

The olfactory pathways provide input to the primitive parts of the ____ cortex first

Answer 31

Ipsilateral

Question 32

How do olfactory pathway project to the neocortex?

Answer 32

Via the thalamus

Question 33

True or False: Unlike olfactory neuroreceptors, taste receptors are specialized epithelial cells that come into contact with a peripheral nerve fiber

Answer 33

True

Question 34

Answer 34

Question 35

Where are taste receptors located?

Answer 35

Taste buds on tongue surface

Question 36

Where does the apical end of taste receptor extend into? Where do sensory fibers attach?

Answer 36

The taste pore Sensory fibers attach to basal surface of receptor

Question 37

Each taste receptor only has lifespan of 1-2 weeks. They are replaced by differentiation of ___ cells to ___ bud

Answer 37

basal cells to taste bud

Question 38

True or False: There are several hundred taste buds per papilla (microscopic)

Answer 38

True

Question 39

Answer 39

Question 40

Taste sensations are carried in peripheral branches of which 3 cranial nerves?

Answer 40

Vagus Glossopharyngeal Facial

Question 41

The superior laryngeal nerve carries taste sensation from area around epiglottis. Which CN does this refer to? A. Vagus B. Glossopharyngeal C. Facial

Answer 41

A. Vagus

Question 42

Chorda tympani nerve carries taste sensation from anterior 2/3 of the tongue. Which CN does this refer to? A. Vagus B. Glossopharyngeal C. Facial

Answer 42

C. Facial

Question 43

True or False: The solitary tract carries taste fibers of CN's 7, 9, and 10 to the nucleus of the solitary tract

Answer 43

True

Question 44

In the ___, the fibers of the solitary tract are surrounded by the nucleus of the solitary tract and will enter and terminate in the nucleus

Answer 44

medulla

Question 45

What is considered to be the principal visceral afferent nucleus in the brainstem?

Answer 45

Nucleus of the solitary tract (NTS)

Question 46

True or False: The nucleus of the solitary tract only receives taste (special visceral afferent - SVA) input

Answer 46

False - the NTS receives BOTH: Special Visceral Afferents (SVA) and General Visceral Afferents (GVA) from CN 9 and 10

Question 47

The Nucleus of the Solitary Tract is divided into two subdivisions: rostral and caudal. Which receives the SVA input? Which receives the GVA input?

Answer 47

Rostral - SVA Caudal - GVA

Question 48

True or False: The NTS contains the 3rd order neurons in the ascending taste pathway

Answer 48

False - contains 2nd order neurons

Question 49

True or False: The axons of the NTS will ascend to the VPL thalamic nucleus, ipsilaterally, in the central tegmental tract

Answer 49

False - The axons of the NTS will ascend to the VPM (!!!) thalamic nucleus, ipsilaterally, in the central tegmental tract

Question 50

Answer 50

Question 51

Where do first order neurons of the taste pathway synapse?

Answer 51

gustatory nucleus (aka: NTS)

Question 52

In the NTS... The rostral receives taste inputs from CN's __, ___, and ___ The caudal receives visceral inputs from CN's __ and __

Answer 52

Rostral = CN 7, 9, and 10 Caudal = CN 9 and 10

Question 53

Taste pathways proceed to cortex via ___

Answer 53

thalamus

Question 54

Where is the insula located?

Answer 54

Insula is the primary taste cortex

Question 55

True or False: The insula projects to the orbital cortex and amygdala for higher integration of taste information

Answer 55

True

Question 56

True or False: Taste pathways are contralateral

Answer 56

False - ipsilateral

Question 57

Where do second order neurons of the taste pathway synapse?

Answer 57

VPM nucleus (thalamus) - VPM projects axons to primary gustatory cortex

Question 58

Unilateral lesions in VPM or NST can result in ____ loss of taste perception A. Ipsilateral B. Contralateral C. Bilatera

Answer 58

A. Ipsilateral

Question 59

___ is complete loss of taste perception

Answer 59

Ageusia

Question 60

___ is the partial loss of taste while ____ is distortion of taste

Answer 60

Hypogeusia; Dysgeusia