Vestibular Sensation & System
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Questions and Answers

What is the primary function of the vestibular ocular reflex?

  • To enhance auditory feedback during movement
  • To control body temperature in response to motion
  • To coordinate limb movement with visual input
  • To stabilize vision when the head is moving (correct)

Which axis corresponds to forward and backward movement in the context of linear translation?

  • W axis
  • Y axis
  • X axis (correct)
  • Z axis

Which type of rotation does the term 'roll rotation' refer to?

  • Forward and backward rotation
  • Side to side rotation (correct)
  • Diagonal rotation
  • Turning on the spot

What do the otolith organs primarily sense?

<p>Gravitational force and linear translation (A)</p> Signup and view all the answers

What is the shape and firing pattern of Type 1 hair cells at rest?

<p>Bulbous shape with irregular firing patterns (D)</p> Signup and view all the answers

What happens to the firing rate of hair cells when stereocilia bend toward the kinocilium?

<p>Firing rate increases (A)</p> Signup and view all the answers

Which structure within the semicircular canals contains the vestibular hair cells?

<p>Crista (A)</p> Signup and view all the answers

How does the push-pull arrangement of the semicircular canals function?

<p>One side increases firing rate while the opposite side decreases (D)</p> Signup and view all the answers

What is the primary factor that causes changes in the firing rate of canal hair cells?

<p>Angular velocity (C)</p> Signup and view all the answers

What role do otoconia play in the function of the otolith organs?

<p>They add weight to the gelatinous layer to enhance sensitivity to gravity (C)</p> Signup and view all the answers

What occurs to the firing rate of hair cells during prolonged constant rotation?

<p>It gradually returns to baseline over time (B)</p> Signup and view all the answers

Which of the following statements reflects the directional sensitivity of the semicircular canals?

<p>Rotations about axes orthogonal to the preferred axis do not cause hair cell activation (A)</p> Signup and view all the answers

How do the otolith organs differentiate between linear acceleration and gravity?

<p>They cannot differentiate between the two (B)</p> Signup and view all the answers

Which rotation refers to the movement around the x-axis?

<p>Roll rotation (A)</p> Signup and view all the answers

The vestibular ocular reflex stabilizes vision by moving the eyes in the same direction as the head.

<p>False (B)</p> Signup and view all the answers

The three axes of linear translation are defined relative to our head and include the x, y, and ______ axes.

<p>z</p> Signup and view all the answers

Match the following terms with their corresponding definitions:

<p>Cristae = Structures in the semicircular canals containing hair cells Endolymph = Fluid that fills the semicircular canals Utricle = Otolith organ that senses horizontal acceleration Saccule = Otolith organ that senses vertical acceleration</p> Signup and view all the answers

What is the result when stereocilia bend away from the kinocilium?

<p>Decrease in firing rate (D)</p> Signup and view all the answers

Each semicircular canal has a unique axis of rotation that is independent of the other canals.

<p>False (B)</p> Signup and view all the answers

What structure is housed within the ampulla of each semicircular canal?

<p>Crista</p> Signup and view all the answers

The otolith organs detect ______ acceleration and gravity.

<p>linear</p> Signup and view all the answers

Match the following parts of the vestibular system with their main functions:

<p>Semicircular canals = Detect rotational movements Utricle = Sense horizontal linear acceleration Saccule = Sense vertical linear acceleration Cupula = Transduce mechanical signals in the canals</p> Signup and view all the answers

How does the firing rate of hair cells during sudden acceleration change?

<p>Firing rate increases followed by a sudden decrease (D)</p> Signup and view all the answers

The cilia of hair cells in the otolith organs are embedded within a gelatinous layer with crystals.

<p>True (A)</p> Signup and view all the answers

Match the following axes with their respective linear translation

<p>X axis = forward movement (through the nose) Y axis = side to side (through the ears) Z axis = up and down axis Axes defined = relative to our head (not gravity)</p> Signup and view all the answers

What does the push-pull arrangement in the vestibular system refer to?

<p>Opposite activity levels in canals with the same preferred axis during the same rotation.</p> Signup and view all the answers

Match the following types of rotation with their axes:

<p>Roll rotation = around x axis (side to side) Pitch rotation = forwards and backwards rotation around y axis (yes/nod) Yaw rotation = turning on the spot movement around z axis (shaking no)</p> Signup and view all the answers

What is the primary function of the otolith organs?

<p>Sense linear translation movement (A)</p> Signup and view all the answers

Type 1 hair cells have a regular firing pattern at rest.

<p>False (B)</p> Signup and view all the answers

What are the three semicircular canals?

<p>Anterior canal, horizontal canal, posterior canal</p> Signup and view all the answers

The stereocilia of hair cells are embedded in a ______ medium.

<p>gelatinous</p> Signup and view all the answers

Match the type of hair cell with its characteristics:

<p>Type 1 = Bulbous shape and irregular firing pattern at rest Type 2 = More elongated and regular firing pattern at rest</p> Signup and view all the answers

Flashcards

Vestibular Sensation

The sense of self-motion and orientation, crucial for balance.

Vestibular-Ocular Reflex

A reflex that keeps vision stable when the head moves by automatically moving the eyes in the opposite direction.

Semicircular Canals

Three fluid-filled tubes in the inner ear detecting rotational movement (roll, pitch, yaw).

Otolith Organs

Structures in the inner ear that sense linear movements and gravity.

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Hair Cells

Sensory receptors in the inner ear, responding to movement of fluid by changing electrical signals.

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Type 2 Hair Cells

Hair cells that are elongated and have a regular firing pattern at rest (when the person is still).

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Stereocilia Bending

The bending of stereocilia in hair cells, towards the tallest one (kinocilium), increases their firing rate, while bending away decreases it.

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Push-Pull Arrangement

Each semicircular canal on one side of the head has a corresponding canal on the other side with the same preferred axis of rotation. Rotation causes an increase in firing rate on one side and a decrease on the other, creating a balance.

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Dynamic Response of Semicircular Canals

Semicircular canals respond to changes in angular velocity (how fast something is rotating). Sudden acceleration causes a fast cupula deflection and firing rate change, but this subsides over time during constant rotation.

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Otolith Organs' Function

Utricles and saccules sense linear acceleration and gravity. They are indistinguishable because both cause otoconia displacement, bending stereocilia.

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Otoconia Displacement

Otoconia, the calcium carbonate crystals on the gelatinous layer, move with linear acceleration or gravity, bending the stereocilia of hair cells.

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Otolith Firing Rate

Otolith hair cells fire proportionally to the tilt or acceleration. Moving towards the kinocilium increases firing, moving away decreases it.

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Equivalence Principle

Linear acceleration and gravity are indistinguishable to the otolith organs, both causing displacement of otoconia and bending of stereocilia.

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Linear Translation

Movement along a straight line, described using three axes (X, Y, Z) relative to the head.

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Rotation

Turning around an axis, categorized as roll (side to side), pitch (forward/backward), and yaw (turning on the spot).

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What happens to hair cells when the stereocilia bend towards the kinocilium?

The firing rate of the hair cell increases.

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What happens to hair cells when the stereocilia bend away from the kinocilium?

The firing rate of the hair cell decreases.

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What causes the otoconia to move?

Linear acceleration and gravity.

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Inner Ear: Rotational Motion

The three semicircular canals (anterior, horizontal, posterior) within the inner ear sense rotational movement in all three axes (roll, pitch, yaw).

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Inner Ear: Linear Motion

The utricle and saccule, also known as the otolith organs, detect linear translation (motion in a straight line) along the x, y, and z axes and also sense gravitational force.

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Hair Cells, Type 1

Type 1 hair cells have a bulbous shape and an irregular firing pattern at rest. They are located in the cristae of the semicircular canals and maculae of the otolith organs.

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Hair Cells, Type 2

These hair cells have an elongated shape and a regular firing pattern at rest. They are also located in the cristae and maculae.

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Study Notes

Vestibular Sensation

  • Sense of self-motion and orientation
  • Balance
  • Stabilizes vision during head movement
  • Vestibular ocular reflex: eyes move opposite to head movement

Linear Translation

  • Axes relative to the head, not gravity
  • X-axis: forward movement (through the nose)
  • Y-axis: side-to-side movement (through the ears)
  • Z-axis: up and down

Rotation

  • Roll rotation: around the x-axis (side-to-side)
  • Ear towards shoulder
  • Pitch rotation: forwards and backwards around the y-axis
    • Example: nodding yes/no
  • Yaw rotation: turning on the spot around the z-axis
    • Example: shaking head "no"

Inner Ear

  • Three semicircular canals (anterior, horizontal, posterior)
    • Sense rotational movement (roll, pitch, yaw)
    • Filled with endolymph
  • Otolith organs: utricle and saccule
    • Sense linear translation and gravity
    • Sense gravitational force
    • X, Y, Z axes

Hair Cells

  • Receptors in the cristae of semicircular canals and maculae of otolith organs
  • Embedded in gelatinous medium
  • Two types
    • Type 1: bulbous shape, irregular firing pattern at rest
    • Type 2: elongated shape, regular firing pattern at rest
  • Stereocilia bending changes firing rate
    • Toward kinocilium (tallest stereocilium): increase firing rate
    • Away from kinocilium: decrease firing rate

Vestibular Transduction

  • Semicircular canals
    • Contain crista with vestibular hair cells
    • Hair cells aligned in the same direction
    • Three canals per side, arranged orthogonally
    • Push-pull arrangement: one side's push creates equal pull on the other
    • Same rotation direction increases firing rate on one side, decreases on the other
  • Directional sensitivity
    • Each canal sensitive to rotations
    • Rotations around other axes do not trigger movement
    • Detect rotations close to preferred axis
    • Sum total of all rotations to determine the final response
  • Dynamic Response
    • Firing rate proportional to angular velocity
    • Sudden changes in acceleration (e.g., sudden starts/stops) lead to sudden changes in firing rate
    • Constant rotation leads to subsidence of cupula movement, and firing returns to baseline after ~15 seconds.
    • Opposite happens when rotation stops
  • Otolith Organs
    • Utricle and saccule (each), containing hair cells and otoconia (calcium crystals)
    • Sense linear acceleration, gravity, movement direction

Otolith Dynamics

  • Constant tilt (or acceleration) proportional firing rate
  • Movement in preferred direction bends stereocilia toward kinocilium = increase firing rate
  • Movement in opposite direction bends stereocilia away from kinocilium = decrease firing rate

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Description

Test your knowledge on vestibular sensation, including the sense of self-motion and balance. This quiz covers the mechanics of linear translation, rotation, and the role of the inner ear structures. Dive into the fascinating world of how we perceive movement and orientation.

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