Olfaction And Taste Flashcards
First symptom when first neurons are damaged
Phantosmia
Sudden feeling that you’re smelling something. Related to trauma or prior to seizure.
Uncinate fits
No sense of smell
Anosmia
Part of limbic system which is associated with memory and emotion
Olfactory bulb
Loss of smell acuity, common in normal aging, decreases apetite
Hyposmia
Located in the roof of the nasal cavity on the inferior surface of the cribriform plate and along the nasal septum and medial wall of superior turbinate
Nasal mucosa
Projections to the dorsomedial nucleus of the thalamus are relayed to the orbitofrontal cortex
Discriminative function of olfaction
Area 28
Entorhinal cortex
Association cortex for olfaction
Area 28
Situated in the anterior part of parahippocampal gyrus
Area 28
Primary olfactory cortex
Prepyriform and preamygdaloid
Secondary olfactory cortex
Area 28
Cell types in bulb and tracts
- mitral
- tufted
- pyramidal
- stellate (granule/golgi II)
Caudal expansion of olfactory tract
Olfactory trigone
Association cortex for olfaction
Area 28
Site of overlap between the limbic and olfactory system
Area 28
Becomes continuous with the diagonal band of broca and has connections to amygdaloid nuclear complex
Medial septal nucleus
Determines whether odor is pleasant or unpleasant
Limbic system
Three pathways of olfaction
- via medial forebrain bundle (most primitive)
- via stria medullaris
- via limbic system
Contains receptor for smell
Olfactory mucosa
Have fibers from anterior olfactory nucleus and cross in the anterior commissure
Medial striae
The second order neuron of bulb and tract
Stellate and tufted
Largest cell of bulb and tract
Mitral
Smallest cell of bulb and tract
Stellate
Third order neuron of bulb and tract
Pyramidal
Well developed sense of smell
Microsmatic
Bathed with serous fluid in which odiferous substances are dissolved
Bowman’s gland
Key structure of olfactory bulb
Glomeruli
Forms intrabulbar circuit for facilitation and regulation activities
Stellate
Termination site of mitral and tufted cells
Anterior olfactory nucleus
Process odor signals
Glomerular mitral cells
Provide mechanical support for the olfactory receptor cells
Sustentacular cells
Give the five layers of olfactory bulb
- olfactory nerve layer
- glomerular layer
- external plexiform
- mitral
- granular
Layer of olfactory bulb where primary dendrites of mitral and tufted cells located
Glomerular
Layer where apical layer of granule cells located
External plexiform
Principal interneuron of olfactory bulb
Granule cells
Inability to recognize smell
Olfactory agnosia
Receive taste input
Insular and olfactory cortex
Appears to play an especially important role in integrating olfactory, taste and other food-related cues that produce the experience of flavor
Medial orbitofrontal cortex
Distortion in a smell experience
Parosmia (dysosmia)
Formation of repugnant or disagreeable olfactory auras
Cascosmia
Aka gustatory cells
Tastebuds
Give rise to taste receptor cells due to continuous turnover, life span 10 - 14 days
Polygonal basal cells
Nerve supply of chorda tympani
CN VII
Principal visceral afferent nucleus of the brainstem
Solitary nucleus
Two division of solitary nucleus
- rostral (gustatory)
- caudal (visceral or cardiorespiratory)
Complete loss of taste
Ageusia
Decreased taste sensitivity
Hypogeusia
Distortions in the perception of a taste
Parageusia (dysgeusia)
Paralysis of stapedius muscle
Hyperacusis