Olfaction & Taste Flashcards
___ contains odorant receptor neurons
superior portion of nasal cavity
Smell starts w/ ___
odorants
ORNs are ___ neurons w/ special sensory cilia. When are they replaced?
Bipolar
Regular basis
Odorants bind to ___ in the ___ & it sends ___ up their axons through ___ to ___
odorant receptors
in the mucus (where olfactory cilia are)
AP
cribriform plate
synapse on olfactory bulb
Odorant receptors are ___ receptors
G protein coupled
Olfactory signals connect to ___ & ___
the limbic system & the cortex
The olfactory bulb first targets limbic structure centers involved in
emotion, reward & memory
What is the pathway for olfaction?
Primary (1) = olfactory receptors travels down the olfactory nerve & synapse on olfactory bulb
Secondary (2) = olfactory bulb travels down the olfactory tract
Tertiary (3*) = olfactory bulb targets limbic structures
What are the following limbic structures responsible for?
Piriform cortex
Entorhinal cortex
Hippocampus
Hypothalamus
Amygdala
Piriform cortex - olfaction
Entorhinal cortex - memory & association
Hippocampus - learning & memory
Hypothalamus - autonomic responses & appetite
Amygdala - emotion
Define hyposmia
reduced ability to detect odors
Define anosmia
complete inability to detect odors
Define parosmia
change in the normal perception of odors
Define phantosmia
sensation of an odor that isn’t there
What are causes of changes in smell?
- Anything that prevents odors from getting to the odorant receptors
- loss of disruption in smell signaling (aging & mental illness)
- congenital anosmia
Cause of loss of smell w/ age
olfactory receptor numbers & olfactory bulb fibers decrease w/ age
Mental illnesses that result in change in smell
Hyposmia & phantosmia can be associated w/ early stages of Alheimers disease, Parkinsons, schizophrenia, & other types of dementia
Mood disorders may also be associated w/ changes in smell
3 kinds of papillae on tongue that have taste buds
- Circumvallate papillae
- Foliate papillae
- Fungiform papillae
What other locations have taste buds?
Epiglottis & hard palate
T/F: Only certain parts of your tongue have taste buds for certain tastes
F
All parts of tongue have taste buds for all of taste
Taste buds are located ___
on the side of papillae
What’s the first cell in taste receptor pathway?
Gustatory Receptor
Taste cells release neurotransmitters, what are they?
serotonin (5-HT), ATP, & GABA (an inhibitory)
G-protein coupled receptor or ion channel receptors for the following:
Salt
Acids
Sweet/umami
Bitter
Salt & acids = ion channels
Sweet/umami & bitter = G protein coupled receptors
CN for anterior part of tongue, side of tongue, back of tongue, epiglottis & hard palate
CN VII innervates anterior part of tongue
CN IX innervates side & back of tongue
CN X innervates epiglottis
CN VII innervates hard palate
Taste pathway
1st neuron = taste buds in CN VII, IX, or X
2nd neuron = nucleus of solitary tract in brainstem
3rd neuron = ventral posterior medial (VPM) of thalamus
4th neuron = gustatory cortex in the insula
Define ageusia
loss of taste
Define dysgeusia & parageusia. What may be its cause?
abnormal or distorted taste
Antibiotics
Chemotherapy or radiation
Gingivitis or caries
Zinc deficiency
Define hypogeusia
decreased taste sensitivity
Define hypergeusia
increased taste sensitivity
Define sensory loss
disruption of sensory perception machinery that creates signals
Define neural loss
damage to or loss of the nerves that carry sensory signals
Define xerostomia. What can it cause?
dry mouth
Lack of saliva due to dissolve testants & deliver them to taste buds
May cause hypogeusia
Does the trigeminal (CN V) contribute to taste?
NO
It only provides signals that can modify sense of taste (like cold, spiciness & astringent)
