Chapter 9 Taste and Smell Flashcards
Where and how do Gustatory and Olfactory systems project to?
-Ipsilaterally and to the cerebral cortex
Four taste qualities?
-Sweet, sour, bitter, and salty
-Fifth (savory) has been proposed
Three taste cranial nerves?
-Facial (VII)
-Glossopharyngeal (IX)
-Vagus (X)
How many neurons in Gustatory System and where?
1st Order Neuron: Taste receptor to rostral solitary nucleus (RSN)
2nd Order Neuron: RSN to VPMN of the thalamus via central tegmental tract
Where does the Ascending Gustatory Pathway project to?
-The Insular Cortex
Where are taste receptors located?
-Taste buds located on tongue and various intraoral sites
What are Tastants and where do they bind to?
-Chemicals from food that bind the surface membrane receptor or pass directly through membrane channels
Ascending Gustatory Pathway Neurons
-1st Order: Taste receptor to RSN in medulla
-2nd Order: RSN to VPMN of thalamus via central tegmental tract
-3rd Order: VPMN of the thalamus to gustatory cortex in insular and frontal operculum
3 Nerves of Gustatory System Location
-Facial Nerve: anterior 2/3 of the tongue, enters at the pontomedullary junction
-Glossopharyngeal nerve: posterior 1/3 of the tongue, enters at the rostral medulla
-Vagus nerve: Epiglottis, enters at the rostral medulla
Primary Olfactory neurons?
-Several million and short lived
(Each p.o.n. has one type of receptor, which determines the spectrum of odorant)
Olfactory Epithelium?
Specialized portion of respiratory epithelial surface that contains primary olfactory neurons
Where is sense of smell mediated and where is it relayed to?
-Olfactory nerve (CN 1)
-Relayed directly to cortex, without first going through the thalamus
What does Odorant interact with
-Transmembrane olfactory receptor on the primary olfactory neuron
Neurons of Olfactory Projection
-1st Neuron: receptor to olfactory bulb
-2nd Neuron: Olfactory bulb to olfactory cortical regions
Where is the entorhinal cortex located and function?
-On the parahippocampal gyrus and allows a smell to evoke memories
