Chemical Senses - von Bartheld Flashcards
Are olfactory nerve fibers myelinated?
NO
Facial fractures can shear the olfactory nerves causing what?
Loss of smell
Is the olfactory nerve long or short?
Short; they are the actual sensory cells that pierce the cribiform plate that then synapse at the olfactory bulb
Is the olfactory tract long or short?
Long; olfactory tract goes back from the olfactory bulb to the cortex
In head trauma, what chemical difference between CSF and snot would help you differentiate between a CSF leak and a runny nose?
CSF has a high glucose concentration
Are olfactory cilia motile?
Noooope
What is the main function of nasal mucus?
Protective
what protein does mucus contain that protects against bacteria?
Immunoglobulins
Basal cells in the nasal mucosa have what function?
They are stem cells that regenerate the receptor cells
what is the lifespan of a receptor cell?
two weeks
Does each receptor cell have its own axon? How does this impact receptor cell turnover?
Yes; axons must also be regenerated and sent back up through the cribiform plate to synapse at the olfactory bulb
Bowman’s glands produce what substance?
mucus
Nasal supporting cells (sustentacular cells) have what function? What neural cell type are they analagous to?
They provide metabolic and physical support for the receptor cells. They are analgous to glial cells
Where are the odorant receptors located on the receptor cells?
On the cilia only, NOT on the body!
What percent of all mammalian genes are devoted to odorant receptors?
3-5%
is the amino acid sequence of odorant receptors highly conserved?
No, it is highly variable to allow bidning of multiple odorants to a single receptor
odorant molecules receptors are ion channles or GPCRs?
GPCRs
Activation of odorant GPCRs opens what ion chanel?
Na/Ca antiporters
Does each receptor cell have all odorant receptors?
No, a receptor cell has only 1-3 receptor types
A combination of (blank) number of receptor subunits makes all of the receptors for all odorants
4
Olfactory glomeruli are made of what types of cells?
Neurons!
The apical dendrites of (blank) cells are also in the olfactory glomeruli
mitral cells
One glomerulus is specialized for how many odors?
1-3
External plexiform layer of the olfactory bulb contains what? (3)
- lateral dendrites of mitral cells
- cell bodies and lateral dendrites of tufted cells
- dendrites of granule cells
the granule layer of the olfactory bulb contains what? (1)
cell bodies of granule cells
What are the interneurons of the olfactory bulb? What cell types do they connect?
Periglomerular cells; they connect mitral cells at the receptor-mitral junction
Where do granule cells connect mitral cells?
Near the cell body
Olfactory (blank) form the glomeruli in the bulb
filae
Glomeruli are the sites where filae synapse on dendrites from (blank) cells and tufted cells
mitral
Mitral and tufted cells poject into what brain structure?
olfactory cortex
What is the name of the olfactory cortex? What topographic brain structure contains it?
The pyriform cortex within the uncus
Does olfaction pass through the thalamus first?
NO, straight to the mothafuckin’ cortex
What gyrus is involved in olfaction?
Cingulate gyrus
What are the four targets of the olfactory bulb?
- Pyriform cortex
- Olfactory tubercle
- Amygdala
- Entorhinal cortex
the pyriform cortex projects its fibers where?
to the orbitofrontal cortex
The Entorhinal cortex projects its fibers where? what process does this link olfaction to?
To the hippocampus; links smells to memories!
Is the thalamus involved at all in olfaction?
Yes, it synapses after the cortex
Does your smell decline with age?
yes
Kallman’s syndrome is a type of :
anosmia (loss of smell)
What are some causes of anosmia or hyposmia?
Viral/sinus infection, head trauma, old age, smoking, halluncinations (new smells), pregnancy
Alzheimer’s, parkinson’s and schizophrenia all show what interesting feature with regard to smell?
Pt’s can all have olfactory hallucinations!
What three crainal nerves mediate taste?
7, 9, 10
Where does CN 7 go with taste information?
to the solitary tract/nucleus solitarius
what sense is the lateral geniculate nucleus involved in?
vision
What sense is the medial geniculate nucleus involved in?
audition
To what nucleus in the thalamus do taste fibers go?
VPM
Do 7, 9, and 10 all go the nucleus solitarius?
Yes!
CN 7 gives taste to what part of the mouth?
Anterior 2/3 of tongue ;)
Cn 9 gives taste to what part of the mouth?
Posterior 1/3 of tongue
CN X gives taste to what part of the mouth?
epi-fuckin-glottis
From the VPM of the thalamus, where do taste fibers go?
To the insula and frontal cortex
Do taste fibers go the amydala or hypothalamus via the insula and frontal cortex?
Amygdala
With regard to the somatotopic map of the cortex, would taste be more medial or lateral?
lateral, in the section for tongue
Sweet/umami taste is found primarily where on the tongue
just the tip ;)
Circumvallate papillae are innervated by what CN?
9
fungiform papillae are innervated by what cranial nerve?
7
anterior foliate papillae are innervated by what cranial nerve?
5
posterior foliate papillae are innervated by what cranial nerve?
9
Sour taste is found where?
sides of the tongue
Bitter taste is found where?
back of the tongue, think about taking gross cough syrup, the flavor always gets stuck back there
salty flavors are found where?
sides of tongue
Each taste bud contains (blank) number of taste cells
50-150
Taste sensory cells are replaced how often
every two weeks
whhat structure from the taste cell extends into the taste pore?
microvilli
do these receptor cells have their own axon?
NO; they synapse onto AFFERENT axons that travel on either the facial or glossalpharyngeal or vagal ganglion cells processes
what are the neurotransmitters used in taste transduction?
Serotonina and ATP
sour taste uses what kind of receptor?
ion channel
Sweet, bitter, and umami use what kind of receptor?
GPCRs
What will happen after activation of any type of taste receptor?
Influx of Ca and then depolarization
At the (basal/apical) side the influx of calcium will lead to the (fusion/exocytosis) of the synaptic vesicle
basal, fusion
What are some causes of aguesia or hypogeusia?
smoking, cystic fibrosis, bell’s palsy, oropharyngeal tumors, chemotherapy
What is cacoguesia?
extremeley unpleasant taste
What are the chemosensitive structures innervated by the trigeminal?
Nose, cornea, tongue, and teeth
What is the function of the chemosensitive structures?
Alert to harmful stimuli and initiate their removal
What innervates the “solitary” receptor cells that resemble taste receptors?
Trigeminal
What is the general rule of three to explain sensory input to the cortex?
- Bipolar cell
- Sensory nucleus
- Thalamus
Why do ascending projections of the cochlear nuclei pass through the superior olivary nucleus?
They are processed there before hitting the thalamus
the medial superior olive processes (intra/inter)aural time differences of 10us
interaural
