Olfactory and Taste B7 Flashcards
What type of cells are the olfactory receptors?
Bipolar olfactory receptor neurons with a single thin apical dendrite and a basally located unmyelinated axon
Where is the olfactory epithelium localized?
Underneath the cribiform plate on the medial wall of the superior nasal turbinate
Odorants, particularly ___________ ones such as musk, cross the mucus by interacting with small proteins called _________________.
hydrophobic
odorant-binding proteins
Where is the olfactory cortex?
medial surface of temporal lobe.
near the uncus and hippocampus
What is a unique aspect of the olfactory system is what?
olfactory bulb projects directly to the cortex
True/False: Anterior olfactory nucleus sends contralateral signal but the rest sends ipsilateral signal
True
Question 3: Describe pathway from receptor to primary olfactory cortex or other targets of the olfactory tract.
Olfactory receptor to mitral cell to ipsilateral olfactory cortex and projects to contralateral cortex
What is the difference between the olfactory nerve and olfactory tract?
Nerves (fila) are basically the receptors that pass through the cribiform plate and the tract is the portion after the bulb
Where is primary olfactory cortex located?
In ventral surface of the brain, adjacent to Uncus
This recognizes the other cortexes. You can smell an orange but this tells us it actually is the orange.
Orbitofrontal cortex and insula
This tells us feeding behavior… determines our hunger. (smells make us hungry)
Hypothalamus
This takes smells and reminds us of something, (how odors can trigger memories)
Hippocampus
What bone fracture will sever the olfactory nerve fibers?
Fracture of Ethmoid bone in cribiform plate
What other pathological conditions or events can cause loss of smell?
(chief complaint is they will say they can’t taste very well)
- Mostly Nasal polyps…
- Rhinitis or sinusitis can block access of odorants to the olfactory epithelium
- Excessive smoking
- Snorting cocaine
- Age-related declines
What type of pathological event can cause olfactory hallucinations?
Perceive smell that doesn’t actually exist
Schizophrenia and Korsakoff psychosis
What type of lingual papillae contain taste buds?
Fungiform papillae
Foliate papillae
Circumvallate papillae
What is the importance of taste buds located in the soft palate, pharynx, and epiglottis?
Detection of food and suppression of aspiration into trachea
4 types of functionally distinct cells in the taste bud
Type 1: mainly perform supportive functions
Type 2: Taste receptor cells; possess Gpcr for bitter, sweet, or umami compounds
Type 3: Synaptic vesicles; cells secrete neurotransmitters
Type 4: Basal cells; progenitor cells
What portion of the tongue is innervated by CN VII and IX?
Anterior ⅔ of tongue Facial Nerve mostly through the Chorda Tympani, but also with greater superficial petrosal nerve innervating soft palate
-Posterior ⅓ of tongue is Glossopharyngeal nerve
Which nerve carries taste from the epiglottis?
Vagus nerve is small area around the epiglottis
Describe path of the chorda tympani?
IPSILATERAL PATHWAY: Cell bodies of facial nerve fibers serving taste are located in the geniculate ganglion. They enter solitary tract and synapse on cells of rostral solitary nucleus…
Which nucleus is the “taste nucleus” in the brainstem? Where in the brainstem is it located?
Rostral solitary nucleus
In geniculate ganglion and enter brainstem at pontomedullary junction…. pons
Does the taste pathway cross the midline?
NO, ipsilateral
Solitary nucleus to VPM to Cortex
What is the clinical term for impaired taste sensation?
Ageusia
- Hypogeusia- decreased taste sensitivity - Parageusia/dysgeusia: distortions in taste perceptions
