T2 L15: Physiology of Balance, Taste and Smell, 8/12/23, SL T2 L15: Physiology of Balance, Taste and Smell, 8/12/23, SL

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Questions and Answers

Which of the following is true about the orientation of the six semicircular canals?

They are oriented at 45-degree angles to each other to detect head rotation in specific directions

They are oriented parallel to each other to detect head rotation in specific directions

They are not oriented in any specific pattern

They are oriented at right angles to one another to detect head rotation in all directions (correct)

Where are the sensory cells in the otolith organs (sacculus and utriculus) located?

Floating freely in endolymph

Attached to the vestibular nerve

Embedded in a gelatinous sheet covered with 'heavy' cristals of calcium carbonate (correct)

Embedded in a cupula

What is the purpose of Epley's maneuver?

To stimulate the vestibular nerve

To realign the semicircular canals

To treat hearing loss

To reposition otoliths (correct)

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 Signup and view all the answers

What is continuous with the endolymph on the apical surfaces of the vestibular hair cells?

The endolymph in the scala media in the cochlea Signup and view all the answers

What do otolith organs enable to resolve?

Head tilt and linear acceleration in all directions Signup and view all the answers

Where are sensory cells in the ampullae of the semicircular canals embedded?

In a cupula Signup and view all the answers

What is embedded in a gelatinous sheet covered with 'heavy' cristals of calcium carbonate?

Sensory cells in otolith organs (sacculus and utriculus) Signup and view all the answers

What is not exactly at right angles to enable it to resolve head tilt and linear acceleration?

Otolith organs (sacculus and utriculus) Signup and view all the answers

How many otolith organs are there?

Four Signup and view all the answers

Which maneuver is designed to dislodge the crystals from the semicircular canals, treating vertigo symptoms?

Epley maneuver Signup and view all the answers

What do otolith organs detect?

Linear acceleration and tilting of the head Signup and view all the answers

What is the function of type I and type II vestibular hair cells?

Type I detects angular acceleration, type II detects linear acceleration Signup and view all the answers

Which test involves irrigation with water of different temperatures to induce eye movements for testing brainstem function?

Caloric testing Signup and view all the answers

What is the main role of the olfactory epithelium located in the nose?

Sense of smell with receptor cells responding to various odors Signup and view all the answers

What is olfactory transduction primarily mediated by?

$cAMP$ activation and opening of ligand-gated ion channels Signup and view all the answers

Which taste modality is responsible for the identification of energy-rich nutrients?

Sweet Signup and view all the answers

What is the primary mechanism for salt sensation in taste transduction?

Equilibrium potential for Na+ ions across the taste receptors Signup and view all the answers

Where is the primary gustatory cortex located?

Frontal lobe Signup and view all the answers

What causes 80% of taste disorders?

Prior upper respiratory tract infection Signup and view all the answers

Which cranial nerves are involved in signaling taste from the rear 1/3 of the tongue to the brainstem?

IX and X Signup and view all the answers

What contributes to the overall pleasure and enjoyment of a meal according to the text?

Umami recognition of amino acids Signup and view all the answers

Where do fibers from second-order taste neurons project to in the brainstem?

Ventral posterior nucleus of the thalamus Signup and view all the answers

What is the primary role of sour and bitter tastes according to the text?

Warning against potentially noxious chemicals Signup and view all the answers

What causes sweet sensation in taste transduction?

Closing K+ channels via a second messenger system Signup and view all the answers

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 Signup and view all the answers

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.

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Description

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.