Lecture for Ch 10.1: Taste and Smell Flashcards
What are taste buds made of?
50-100 specialized epithelial cells with long microvilli that extend out of taste bud pore
Types of papillae on tongue
1) fungiform
2) circumvallate
3) foliate
Fungiform Papillae
on the anterior surface of the tongue, innervated by the facial nerve
Circumvallate Papillae
on the posterior surface of the tongue, innervated by the glossopharyngeal nerve
Foliate Papillae
on the side of the tongue innervated by the glossopharyngeal nerve
Taste Pathways
facial & glossopharyngeal –> medulla oblongata –> thalamus –> primary gustatory cortex of insula/somatosensory lobe/prefrontal cortex
What part of the taste bud comes in contact with chemicals?
microvilli
True/false: each taste buds has sensory cells for each taste category
TRUE
Taste is influenced by the _____ and _____ of the substance
temperature; texture
How does salty reception work?
Na+ received by the hair cell through ion channels, causes depolarization, opens Ca channels to release NT to the synapse for the facial or glossopharyngeal nerve to receive stimulation
How does sour reception work?
H+ received by the hair cell through ion channels, causes depolarization, opens Ca channels to release NT to the synapse for the facial or glossopharyngeal nerve to receive stimulation
How does sweet/umami reception work?
sugar or glutamate binds to receptor, activating g-proteins/2nd messngr to release Ca++ and close K+ channels
How does bitter reception work?
Quanine binds, activating G-protein/2nd messngr to release Ca++ from endoplasmic reticulum; VERY sensitive to [LOW] as a protective response
What are g-proteins called in the gustation system?
gustducins
Which 2nd messngr is activated in sugar reception?
adenylate cyclase, producing cAMP
What other 2nd mssngr molecules can be active in gustation?
IP3 (inositol triphosphate) and DAG (diacylglycerol)
Where are olfactory receptors located?
in the olfactory epithelium of the nasal cavity
Sustentacular cells
olfactory cells that oxidize hydrophobic volatile odors
What do basal stem cells do in olfaction?
They replace receptors damaged by the environment
Anatomy of olfactory receptors
bipolar neurons with ciliated dendrites projecting into the nasal cavity
What structure binds to odors?
proteins on the cilia of bipolar neurons
How many different olfactory receptors do humans have?
~380
1 odorant molecule stimulates ___ protein(s)
1
How does smell reception work?
G-protein system stimulates activation of adenylate cyclase; produces cAMP to open Na and Ca channels; produces graded depolarization to produce AP
How many G-proteins may be associated with 1 receptor protein in olfaction? What does this cause?
up to 50 = great sensitivity via amplification
Are olfactory neurons myelinated?
No
Where do olfactory neurons synapse?
on a specific type of glomerulus/group of glomeruli (by smell type, depending on complexity) in the olfactory bulb
Odor identification is improved by _______
lateral inhibition
What structures of the glomeruli synapse onto the olfactory cortex of the frontal and parietal lobes?
mitral and tufted neurons
The piriform cortex is part of the _____ system
olfactory
Where does smell stimulation travel after it reaches the piriform cortex?
hippocampus, amygdala, limbic system (bypasses the thalamus)
Where does taste connect with smell?
at the prefrontal cortex
