06a: Peripheral Vestibular System Flashcards
The vestibular receptors are actually (X).
X = hair cells
Where are the vestibular receptors located?
- Semicircular canals
2. Utricle and saccule (maculae)
Vestibular nuclei send axons to:
- Cerebellum
- Extra-ocular muscle nuclei
- Reticular formation
- SC
Vestibular receptors are divided into which groups?
- Static receptors
2. Kinetic receptors
List the (X) vestibular receptors, which respond to linear accelerations.
X = static
Maculae of the utricle and saccule
List the (X) vestibular receptors, which respond to angular accelerations.
X = kinetic
Cristae of semicircular canals
Which vestibular receptors play prominent role in signaling static position of head?
Static receptors
Which vestibular receptors play prominent role in signaling angular velocity of (rotating) head?
Kinetic receptors
List the three major functions of the vestibular system.
- Subjective sensation of motion/spatial orientation
- Postural control
- Stabilizing eyes during head movement
T/F: Most of vestibular system’s actions are reflexive (occur at unconscious level).
True
T/F: Our perception of spatial orientation is essentially completely dependent on vestibular input.
False
T/F: At rest, vestibular primary afferents discharge action potentials.
True
Bending of (X) toward kinocilium causes (Y). And away causes (Z).
X = sterocilia; Y = depolarization of HCs Z = hyper-polarization of HCs
Bending of (X) toward kinocilium is associated with (increase/decrease) in firing frequency of (Y).
X = sterocilia;
Increase;
Y = primary afferent fibers
The amplitude of depolarization/hyperpolarization of hair cells depends on:
Direction of bending of cilia, relative to kinocilium
Bending of cilia perpendicular to kinocilium will (depolarize/hyperpolarize) HC.
Neither - no change in HC voltage if perpendicular
In the (X), the macula is approximately horizontal when body is upright. And in the (Y), it’s vertical.
X = utricle; Y = saccule
In the otolith organs, the cilia are embedded in (X) containing (Y) called “otoconia”.
X = gelatinous material (otolithic membrane) Y = CaCO3 crystals
Otoconia function in bending motion.
Make otoliths denser than endolymph, causing Otolithic membrane (and cilia of HCs) to sag
Otoconia function in linear acceleration.
Heavier otoliths lag behind (due to inertia), bending cilia of HCs
Degree of tilt/head movement is indicated by (X).
X = frequency of firing of primary afferents
The direction of movement is indicated by (X).
X = which primary afferents (or HCs) are active
The magnitude of head movement is indicated by:
Change in rate of firing of primary afferent fibers
In semicircular canals, the HCs are embedded in (X), which extends into the (Y) fluid that fills the canals.
X = cupula (gelatinous material) Y = endolymph
Why (does/doesn’t) the cupola move with respect to the (X) during linear acceleration?
Doesn’t;
X = semicircular canal;
Same specific gravity as endolymph that fills canal
Movement of endolymph in (X) causes (Y) to swing like a door.
X = semicircular canal; Y = cupula
On each side of the head, there are (X) number of semicircular canals, all (parallel/perpendicular) to each other. List them.
X = 3; perpendicular;
Horizontal, anterior, posterior
List the complimentary pairs of the semicircular canals.
- L and R horizontal
- L posterior with R anterior
- R posterior with L anterior
Horizontal semicircular canals are perfectly horizontal if head is in which position?
Tilted forward 30 degrees
Depolarization of hair cells is due to (X) ion moving down (chemical/electrical) gradient from (Y) space to (Z) space.
X = K+
Electrical;
Y = endolymph
Z = HC
Endolymph has high concentration of (X) ions and low concentration of (Y) ions. What’s the typical potential (in mV) of this space?
X = K+ Y = Na and Ca
+80 mV
The (X) membrane separates the endolymph from the (Y).
X = reticular Y = perilymph
Perilymph has high concentration of (X) ions and low concentration of (Y) ions. What’s the typical potential (in mV) of this space?
X = Na Y = K
0 mV
The hair cells have high concentration of (X) ions and low concentration of (Y) ions. What’s the typical potential (in mV) of this space?
X = K Y = Na
-40 mV
In any one semicircular canal, how do the HCs differ in orientation?
They don’t! Identical orientation
Saccule respons best to movements in which plane?
Saggital (front/back movement)
Utricle respons best to movements in which plane?
Frontal (L/R movement)
The striola is present in (otolith organs/semicircular canals) and functions to:
Otolith organs;
Divides hair cells into two populations with opposite polarities
The macula of the otolith organs is analogous to (X) of semicircular canal. Define these.
X = Crista;
Sensory epithelium that contains the hair cells
Semicircular canals respond only to which type of movement?
Changes in velocity (angular acceleration)
You turn your head to the right, primarily activating (X) vestibular structures. Describe direction of fluid flow.
X = horizontal semicircular canals;
R: toward ampulla
L: away from ampulla
You turn your head to the right. Where does the de/hyper-polarization happen?
Depolarization in R horizontal semicircular canal. Hyperpolarization in L canal.
T/F: Difference in response of semicircular canal pairs is due to opposite orientation of hair cells and kinocilium between the pairs.
False - due to opposite movement of fluid within canal pairs
Pressure exerted by fluid on cupula is in the (same/opposite) direction as the head rotation.
Opposite
