Lecture 15: Olfaction and Taste Flashcards
Animals with well developed olfactory system are referred to as _____
Humans, by contrast, are ___ and rely less on their sense of smell
Animals = macroscopic
Humans = microscopic
True or False: Olfaction is important for memories, emotions, sexual
activities and TASTE
True
____ (loss of sense of smell) impairs taste
Anosmia
True or False: The olfactory mucosa is located
in the lateral/medial part of
nasal cavity
False - superior/posterior
True or False: The olfactory mucosa is made up of cuboidal epithelium layer and is surrounded by neuroreceptors
False - consists of COLUMNAR epithelial layer
True or False: Olfactory receptors communicate
with the external environment
True
____ are the only neurons that communicate with the external environment and undergo constant replacement
Olfactory neuroreceptors
Basal cells near the lamina propria undergo differentiation and develop into olfactory neuroreceptors ever ____
5-8 weeks
True or False: The bipolar olfactory neurons have several dendrites that project toward apical mucosa
False - have one dendrite that projects toward apical mucosa
True or False: Myelinated axons of the bipolar neurons constitutes the olfactory nerve
False - unmyelinated axons
How do olfactory nerve pass from the nasal cavity to the interior of the braincase? Where does it terminate?
Foramina (in cribiform plate of ethmoid bone)
Terminates in olfactory bulbs
Which of the following has receptors for odorants?
A. Foramina
B. Olfactory neuroreceptors
C. Cilia
C. Cilia
True or False: Density of odorant
receptors is higher in
macrosmatic animals
True
What is the first processing
station for olfactory info?
Olfactory bulb
Olfactory bulb contains 2nd order neurons, which are known as ___ cells
mitral cells
Which of the following forms the
olfactory tract?
A. Mitral axons
B. Olfactory axons
C. Cilia axons
A. Mitral axons
Where are mitral cells found?
Olfactory bulb
True or False: Olfactory receptors are activated
by specific odorant molecules
True
____: Prominent fiber tracts from the olfactory bulbs, which course towards the ANTERIOR PERFORATED SUBSTANCE
Olfactory Tract
At the anterior perforated substance, the olfactory tract splits into two striate:
1.
2.
Medial Olfactory Stria
Lateral Olfactory Stria
True or False: Lateral Olfactory Stria project to SEPTAL areas
False - Medial Olfactory Stria project to SEPTAL areas
Medial olfactory stria fibers
project to which four SEPTAL areas?
- Thalamus (DMN)
- Hypothalamus
- Hippocampus
- Upper Brainstem
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
True
True or False: The lateral olfactory stria contains
majority of olfactory tract fibers
True
Which two areas does the lateral olfactory stria carry information to?
- Olfactory cortices
- Areas surrounding
amygdala
Olfactory cortices are collectively
known as ____ cortex
piriform cortex
Compare and contrast the
Primary Olfactory Cortex (AKA
prepiriform) to the Olfactory Association Cortex (AKA
entorhinal)
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
True or False: Olfactory pathways ARE required to
relay in the thalamus
False - they are NOT
The olfactory pathways provide input to the primitive parts of the ____ cortex first
Ipsilateral
How do olfactory pathway project to the neocortex?
Via the thalamus
True or False: Unlike olfactory neuroreceptors, taste receptors are specialized epithelial cells that come into contact with a peripheral nerve fiber
True
Where are taste receptors located?
Taste buds on tongue surface
Where does the apical end of taste receptor extend into?
Where do sensory fibers attach?
The taste pore
Sensory fibers attach to basal surface of receptor
Each taste receptor only has lifespan of 1-2 weeks. They are replaced by differentiation of ___ cells to ___ bud
basal cells to taste bud
True or False: There are several hundred taste buds per papilla (microscopic)
True
Taste sensations are carried in
peripheral branches of which 3 cranial nerves?
Vagus
Glossopharyngeal
Facial
The superior laryngeal nerve carries taste sensation from area around epiglottis.
Which CN does this refer to?
A. Vagus
B. Glossopharyngeal
C. Facial
A. Vagus
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
C. Facial
True or False: The solitary tract carries taste fibers of CN’s 7, 9, and 10 to the nucleus of the solitary tract
True
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
medulla
What is considered to be the principal visceral afferent nucleus in the brainstem?
Nucleus of the solitary tract (NTS)
True or False: The nucleus of the solitary tract only receives taste (special visceral afferent - SVA) input
False - the NTS receives BOTH: Special Visceral Afferents (SVA) and General Visceral Afferents (GVA) from CN 9 and 10
The Nucleus of the Solitary Tract is divided into two subdivisions: rostral and caudal. Which receives the SVA input? Which receives the GVA input?
Rostral - SVA
Caudal - GVA
True or False: The NTS contains the 3rd order neurons in the ascending taste pathway
False - contains 2nd order neurons
True or False: The axons of the NTS will ascend to the VPL thalamic nucleus, ipsilaterally, in the central tegmental tract
False - The axons of the NTS will ascend to the VPM (!!!) thalamic nucleus, ipsilaterally, in the central tegmental tract
Where do first order neurons of the taste pathway synapse?
gustatory nucleus (aka: NTS)
In the NTS…
The rostral receives taste inputs from CN’s __, ___, and ___
The caudal receives visceral inputs from CN’s __ and __
Rostral = CN 7, 9, and 10
Caudal = CN 9 and 10
Taste pathways proceed to cortex via ___
thalamus
Where is the insula located?
Insula is the primary taste cortex
True or False: The insula projects to the orbital cortex and amygdala for higher integration of taste information
True
True or False: Taste pathways are contralateral
False - ipsilateral
Where do second order neurons of the taste pathway synapse?
VPM nucleus (thalamus)
- VPM projects axons to
primary gustatory
cortex
Unilateral lesions in VPM or NST can result in ____ loss of
taste perception
A. Ipsilateral
B. Contralateral
C. Bilatera
A. Ipsilateral
___ is complete loss of taste
perception
Ageusia
___ is the partial loss of taste while ____ is distortion of taste
Hypogeusia; Dysgeusia
