Chapter 15 Flashcards
(28 cards)
Where does taste discrimination occur?
in the secondary gustatory cortex
What 3 cranial nerves innervate our taste buds?
CN VII - geniculate ganglion (anterior 2/3)
CN IX - petrosal (ganglion posterior 1/3)
CN X - nodose ganglion (epiglottic & palatal portions)
How does transduction of taste bud start?
a hair cell (microvilli) interacts with an ion channel causing depolarization which sends the action potential via synapsing with primary afferents.
From the 3 ganglion were does the gustatory pathway go next?
the 3 ganglion send afferent input to solitary nucleus/tract synapsing at rostral enlargement (gustatory nucleus) in rostral medulla.
Where does the secondary connections of the gustatory pathway go to?
secondary connections proceed from solitary nucleus to the VPM (small cell parvicellular part)
From the parvicellular part of VPM where does the gustatory pathway go to?
from VPM, via the gustatory radiations in the posterior limb of internal casual to the primary gustatory cortex.
From the primary gustatory cortex where does the gustatory pathway go to?
fibers project to the secondary gustatory cortex.
What is anosmia?
loss of smell
A sudden or gradual loss of smell can help the PT distinguish what?
sudden loss - damage to olfactory receptors (trauma)
gradual loss - may be due to tumor growth
Lesion to orbitofrontal cortex will result in?
loss of ability to identify smell and taste.
Irritative lesions to uncut results in?
olfactory hallucinations (aura) - is smelling something that is not present.
what is the term for poor sense of smell?
miscrosmatic
What is the lifespan of olfactory neurons?
4-8 weeks
Primary receptors of the olfactory system are located where?
olfactory mucosa
1 square inch in superior nasal concha & upper nasal septum
In order for odors to be smelled, odorants must…?
dissolve in the mucus to stimulate receptors in the cilia
How is the primary olfactory neuron activated?
once odor is on cilia receptor, an intermediate second messenger cyclic nucleotide pathway is activated, opening the ion channels generating the action potential.
What is the olfactory nerve made of?
central branches of the bipolar olfactory neurons - that is about 20 non-myelinated fiber are bundled, cross cribriform plate, are myelinated after crossing, and terminate at olfactory bulb.
What is the most prominent cells in the olfactory bulb?
mitral cells
What makes up the olfactory glomeruli?
mitral cells and olfactory nerve fibers - a thousand olfactory nerve fibers can synapse on one mitral cell
What forms the olfactory tract?
axons from the mitral cells
What does the olfactory tract consist of?
- mostly fibers of mitral cells
- neurons that form anterior olfactory nucleus
- certrifugal fibers from contralateral anterior olfactory nucleus
- fibers from basal forebrain to modulate olfactory bulb neurons
What happens at the posterior end of the olfactory tract?
the olfactory tract splint, called the olfactory trigone, forming a medial olfactory striae and lateral olfactory striae
Where does the medial olfactory striae arise and what does it project?
arises from the anterior olfactory nucleus and projects via olfactory part of the anterior commissure to the contralateral olfactory bulb.
Where does the lateral olfactory striae project?
carries input directly to the primary olfactory cortex
