Chemosensation - Restrepo Flashcards
loss of sense of taste
Ageusia
Altered perception of taste
Dysgeusia
Loss of sense of smell
Anosmia
Diminished sense of smell
Hyposmia
Altered or distorted sense of smell
Dysosmia
Altered perception of smell in the prescence of an odor, usually unpleasant
Parosmia
Phantosmia
Ghost perception of smell
Stimulation of what three senses defines what we generally define as “taste”?
What cranial nerves are responsible for each?
Onto what nucleus does each synapse?
Olfaction - CN 1, Olfactory bulb
Gustation - CN 7, 9, (10), Solitary nucleus
Chemesthesis - CN 5, SPINAL TRIGEMINAL NUCLEUS
Chemotherapy damages rapidly dividing cells. What two groups of cells involved in “taste” will be affected?
Olfactory receptor neurons
Taste buds
What is the receptor type for CN 5 receptors that sense chemesthesis?
Free nerve endings in the mucosa.
What is the receptor type for CN 7, 9, 10?
Modified epithelial cell
What is the receptor type for CN1?
Ciliated, bipolar neuron
Papillae located on the front of the tongue are called _____ and are innervated by the _____.
Fungiform, Facial nerve (chorda tympani)
Papillae located on the posterior 1/3 of the tongue are called _____ and are innervated by _____.
Circumvallate, Glossopharyngeal
Taste buds located in the soft palate are innervated by the ______.
superior petrosal branch of the facial nerve
Taste buds in the _____, _____, and _____ are supplied by the vagus. Taste buds in these posterior areas are thought to be important in gag reflexes designed to stop intake of spoiled foods or noxious compounds.
extreme posterior tongue, oropharynx and epiglottis
You drink hot coffee and burn the f*%& out of the front part of your tongue. What nerve has notified your brain of this unfortunate situation?
CN5.
Sour, sweet, salty, umami, bitter. Which of these are ion-channel based vs. G-protein coupled?
Ion channel: Sour, salty
Gprotin: Sweet, umami, bitter
Taste Transduction for sweet, umami, bitterinvolves a complex G-protein coupled, biochemical amplification system. What neurotransmitter is used?
ATP.
After CN 7, 9, 10 synapse on the nucleus of the solitary tract, they send axons to two primary destinations. What are they, and what purpose does each serve?
Insular cortex (conscious appreciation of taste)
Amygdala/Hypothalamus (appetite control, sub conscious reactions to taste)
What area of the brain receives input from both olfactory and gustatory neurons, and is the likely location where the perception of “taste” is formed?
the orbitofrontal cortex.
The olfactory neuron must depolarize to send a signal to the olfactory bulb? What feature is unique about this pathway?
G-protein coupled.
Golf–> AC –> cAMP –> Na/Ca channel opens–> high Ca levels –> Cl- channel–> Cl LEAVES, furthering
depolarization.
So the unique feature is a high intracellular concentration of Cl- with regard to the ECF.
Axons of the olfactory nerve must penetrate the cribriform plate, which is part of the ___ bone, to reach the olfactory bulb.
ethmoid
Each taste bud contains 50-100 taste cells, each with the (same or different) receptor specificity. Afferents from these taste cells travel to the olfactory bulb where they synapse onto a glomerulus which is (specific or nonspecific) for a given receptor specificity.
Different, specific
This creates a flavor “map” on the bulb, which allows the brain to differentiate.
**receptors can bind more than one type of molecule, so a given molecule may activate many glomeruli. The system is similar to the visual pathway where the brain must recognize a pattern to distinguish individual flavors.
True or false. The olfactory system is the only sense that transmits directly to the cortex, bypassing the thalamus.
True of false. Also projects to the amygdala.
True dat.
True. That’s why people hook up with their ex…probably.
Smell association with memory takes what path from the olfactory bulb to its final destination?
Olfactory bulb–>tract–>entorhinal cortex–>hippocampus
Smell association with conscious perception takes what path from the olfactory bulb to its final destination?
Olfactory bulb–>tract–>Piriform cortex–>MD thalamus –>orbitofrontal cortex (remember this is where it meets up with gustatory neurons)
Smell association with Visceral reactions and homeostasis take what path from the olfactory bulb to its final destination?
Bulb–>tract–>olfactory tubercle OR amygdala–> hypothalamus
