26 Questions
Which of the following is true about the orientation of the six semicircular canals?
They are oriented at right angles to one another to detect head rotation in all directions
Where are the sensory cells in the otolith organs (sacculus and utriculus) located?
Embedded in a gelatinous sheet covered with 'heavy' cristals of calcium carbonate
What is the purpose of Epley's maneuver?
To reposition otoliths
How are the ampulla of the superior (anterior) semicircular canal and the ampulla of the posterior semicircular canal functionally paired?
The left anterior and right posterior canals are functionally paired, as are the left posterior and right anterior canals
What is continuous with the endolymph on the apical surfaces of the vestibular hair cells?
The endolymph in the scala media in the cochlea
What do otolith organs enable to resolve?
Head tilt and linear acceleration in all directions
Where are sensory cells in the ampullae of the semicircular canals embedded?
In a cupula
What is embedded in a gelatinous sheet covered with 'heavy' cristals of calcium carbonate?
Sensory cells in otolith organs (sacculus and utriculus)
What is not exactly at right angles to enable it to resolve head tilt and linear acceleration?
Otolith organs (sacculus and utriculus)
How many otolith organs are there?
Four
Which maneuver is designed to dislodge the crystals from the semicircular canals, treating vertigo symptoms?
Epley maneuver
What do otolith organs detect?
Linear acceleration and tilting of the head
What is the function of type I and type II vestibular hair cells?
Type I detects angular acceleration, type II detects linear acceleration
Which test involves irrigation with water of different temperatures to induce eye movements for testing brainstem function?
Caloric testing
What is the main role of the olfactory epithelium located in the nose?
Sense of smell with receptor cells responding to various odors
What is olfactory transduction primarily mediated by?
$cAMP$ activation and opening of ligand-gated ion channels
Which taste modality is responsible for the identification of energy-rich nutrients?
Sweet
What is the primary mechanism for salt sensation in taste transduction?
Equilibrium potential for Na+ ions across the taste receptors
Where is the primary gustatory cortex located?
Frontal lobe
What causes 80% of taste disorders?
Prior upper respiratory tract infection
Which cranial nerves are involved in signaling taste from the rear 1/3 of the tongue to the brainstem?
IX and X
What contributes to the overall pleasure and enjoyment of a meal according to the text?
Umami recognition of amino acids
Where do fibers from second-order taste neurons project to in the brainstem?
Ventral posterior nucleus of the thalamus
What is the primary role of sour and bitter tastes according to the text?
Warning against potentially noxious chemicals
What causes sweet sensation in taste transduction?
Closing K+ channels via a second messenger system
Where do most parts of the tongue have sensitivity to all five modalities of taste according to the text?
Considerable overlap so that most parts can detect all five modalities
Study Notes
Benign Paroxysmal Positional Vertigo (BPPV) and Olfactory System
- BPPV is the most common inner ear disorder, caused by displaced calcium crystals in the inner ear, leading to vertigo.
- The Epley maneuver is a series of movements designed to dislodge the crystals from the semicircular canals, treating vertigo symptoms.
- Vestibular hair cells come in two types: type I and type II, with functional differences still somewhat unclear.
- Semicircular canal receptors detect head rotation and are involved in the vestibulo-ocular reflex and nystagmus.
- Caloric testing can be used to test brainstem function in unconscious patients, involving irrigation with water of different temperatures to induce eye movements.
- Otolith organs detect linear acceleration and tilting of the head, and provide the same stimulus to the sacculus and utriculus.
- Central vestibular pathways and causes of vestibular disorders include ear infections, head injuries, whiplash, aging, and certain drugs.
- Vestibular disorders present as dizziness, light-headedness, and vertigo, with potential traumas and specific conditions like BPPV and Ménière's disease.
- The olfactory epithelium, located in the nose, plays a major role in the sense of smell, with receptor cells responding to various odors.
- Olfactory transduction is a second messenger process, involving cAMP activation and opening of ligand-gated ion channels.
- Clinical issues with olfaction include hyposmia and anosmia, affecting 5-10% of the population, with causes such as respiratory tract infections, head trauma, and certain drugs.
- Reduced quality of life is associated with olfactory disorders, impacting social interactions, avoidance of poisons, and enjoyment of food.
This module covers the organization of the vestibular system, functions of semicircular canals and otolith organs, central vestibular pathways, olfactory transduction, taste transduction, and the organization of the peripheral vestibular system. It also touches upon the anatomical structures such as the ampullae of the semicircular canals.
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