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Questions and Answers
The otoliths are completely attached to the gelatinous layer.
The otoliths are completely attached to the gelatinous layer.
False (B)
The macula is subjected to linear acceleration when the body is standing still.
The macula is subjected to linear acceleration when the body is standing still.
False (B)
The utricle is stimulated when the body is oriented horizontally.
The utricle is stimulated when the body is oriented horizontally.
False (B)
The saccule acts as a tonic receptor because it's continuously stimulated by gravity when standing still.
The saccule acts as a tonic receptor because it's continuously stimulated by gravity when standing still.
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The brain receives information from both the saccule and the utricle when standing still.
The brain receives information from both the saccule and the utricle when standing still.
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The utricle is not stimulated during the descending phase of a jump.
The utricle is not stimulated during the descending phase of a jump.
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The saccule is responsible for maintaining a sense of equilibrium in the body.
The saccule is responsible for maintaining a sense of equilibrium in the body.
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The cilia are embedded in the gelatinous layer and directly stimulate the receptors.
The cilia are embedded in the gelatinous layer and directly stimulate the receptors.
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The stimulation of the receptors in the ear is entirely a chemical process.
The stimulation of the receptors in the ear is entirely a chemical process.
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During a jump, the saccule and the utricle experience the same force from gravity.
During a jump, the saccule and the utricle experience the same force from gravity.
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The vestibular system in vertebrates is exclusively responsible for acoustic perception.
The vestibular system in vertebrates is exclusively responsible for acoustic perception.
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The utricle and saccule are primarily responsive to rotational movements of the head.
The utricle and saccule are primarily responsive to rotational movements of the head.
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The vestibular system can only monitor linear acceleration of the head under gravitational force.
The vestibular system can only monitor linear acceleration of the head under gravitational force.
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The labyrinth is a part of the vestibular system that is located in the temporal bone.
The labyrinth is a part of the vestibular system that is located in the temporal bone.
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The vestibular system helps maintain upright posture by allowing the center of gravity to shift unpredictably.
The vestibular system helps maintain upright posture by allowing the center of gravity to shift unpredictably.
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The semicircular canals only provide background discharge during head movement.
The semicircular canals only provide background discharge during head movement.
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The cupola is rigidly fixed to the ceiling of the ampulla.
The cupola is rigidly fixed to the ceiling of the ampulla.
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Inertia of the endolymph causes the cupola to bend in the same direction as the head movement.
Inertia of the endolymph causes the cupola to bend in the same direction as the head movement.
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The cilia of the hair cells are bent during constant motion, providing continuous stimulation.
The cilia of the hair cells are bent during constant motion, providing continuous stimulation.
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The system primarily focuses on the fast transient phase of stimulation.
The system primarily focuses on the fast transient phase of stimulation.
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All semicircular canals have the same function and provide the same type of feedback.
All semicircular canals have the same function and provide the same type of feedback.
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The hair cells in the semicircular canals are embedded in the base of the cupola.
The hair cells in the semicircular canals are embedded in the base of the cupola.
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When the motion is stopped, the movement of the fluid causes the cilia to deflect towards the direction of the last movement.
When the motion is stopped, the movement of the fluid causes the cilia to deflect towards the direction of the last movement.
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Phasic receptors are only concerned with the onset of stimulation and not the offset.
Phasic receptors are only concerned with the onset of stimulation and not the offset.
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The fluid filling the semicircular canals is known as perilymph.
The fluid filling the semicircular canals is known as perilymph.
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Bending the hairs of hair cells in one direction decreases the rate of firing in afferent fibres within the vestibular nerve.
Bending the hairs of hair cells in one direction decreases the rate of firing in afferent fibres within the vestibular nerve.
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The OFF-centre/ON-surround mechanism in the eye is responsible for providing information about light stimulating the surround.
The OFF-centre/ON-surround mechanism in the eye is responsible for providing information about light stimulating the surround.
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Thermal stimulation can alter the viscosity of the cupola in the semicircular canals.
Thermal stimulation can alter the viscosity of the cupola in the semicircular canals.
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Alcohol has no effect on the sensitivity of the cupola within the vestibular system.
Alcohol has no effect on the sensitivity of the cupola within the vestibular system.
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Otolith organs only provide information when the head is in motion.
Otolith organs only provide information when the head is in motion.
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The brain continuously monitors gravitational force even when there is no movement.
The brain continuously monitors gravitational force even when there is no movement.
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The arrangement of ON-centre/OFF-surround is sufficient to provide a clear idea of the light in the surround.
The arrangement of ON-centre/OFF-surround is sufficient to provide a clear idea of the light in the surround.
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Otoliths are sensitive to gravitational force and can become detached from the maculae.
Otoliths are sensitive to gravitational force and can become detached from the maculae.
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The semicircular canals are not affected by changes in the stiffness of the cupola.
The semicircular canals are not affected by changes in the stiffness of the cupola.
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The perception of contrast is grounded solely on the ON-centre/OFF-surround arrangement.
The perception of contrast is grounded solely on the ON-centre/OFF-surround arrangement.
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The brain is aware of body movement only when there is stimulation from the otoliths.
The brain is aware of body movement only when there is stimulation from the otoliths.
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When moving in a lift, the situation of standing still requires less stiffness for the otoliths to move.
When moving in a lift, the situation of standing still requires less stiffness for the otoliths to move.
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Linear movement refers to movement that is aligned with the direction of the gravity force.
Linear movement refers to movement that is aligned with the direction of the gravity force.
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Maculae can detect movements irrespective of the direction of the gravitational force.
Maculae can detect movements irrespective of the direction of the gravitational force.
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The bending of both utricles and saccules occurs exclusively when moving parallel to the force of gravity.
The bending of both utricles and saccules occurs exclusively when moving parallel to the force of gravity.
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Proprioception helps differentiate between head movement alone and the movement of the body combined with the head.
Proprioception helps differentiate between head movement alone and the movement of the body combined with the head.
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The activation of receptors in a macula is determined solely by the direction of body movement.
The activation of receptors in a macula is determined solely by the direction of body movement.
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The vestibular system cannot function effectively without proprioceptive information from the neck.
The vestibular system cannot function effectively without proprioceptive information from the neck.
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Study Notes
The Vestibular System
- The vestibular system is the "inertial guidance system" in vertebrates, monitoring movement in space.
- It comprises five sensory organs in the inner ear.
- Monitors linear and angular acceleration of the head, the location of sensory organs is in the inner ear.
- Capable of understanding head movement alone and with the whole body.
Functions of the Vestibular System
- Keeps the eyes still during head movements (walking).
- Maintains upright posture by maintaining the centre of gravity.
- Provides sensory input for proprioception and perception of space around us.
Vestibular System Anatomy
- The primary component is the labyrinth, a set of interconnected chambers continuous with the cochlea.
- The labyrinth includes the cochlea (acoustic system) and the vestibular system.
- Located deep within the temporal bone.
- Contains two otolith organs (utricle and saccule) and three semicircular canals (superior, posterior, and lateral).
Semicircular Canals
- Located in the labyrinth and are tube-like structures leading to ampullae (enlarged portions).
- Filled with endolymph.
- Cilia of the receptors are located at their base, connected to afferent fibers of the vestibular nerve.
- The gelatinous cupola surrounds the cilia.
Maculae
- Located in the saccule and the utricle.
- Contain hair cells and statoconia (calcium carbonate crystals).
- Otoconia weigh down the gel and displace cilia.
- Detect linear acceleration and head orientation. Utricle detects horizontal orientation, saccule detects vertical orientation.
Vestibular Stimulation
- Stimulation is mechanical, with cilia deflection causing depolarization (excitation) or hyperpolarization (inhibition).
- Background discharge signals whether the receptor is at rest, active or inactive.
- Background impulses frequency changes depending on depolarization or hyperpolarization which cause excitation or inhibition respectively.
Architecture Matters
- Kinocilia (tallest cilia) are always oriented in one direction.
- Cilia of different cells deflect either in one direction or the opposite.
- Receptors are arranged in a series in which all the cilia will be excited or inhibited in the same direction.
Mechanical Stimulation
- Semicircular canals detect angular acceleration/deceleration of the head
- Maculae detect linear acceleration/deceleration and head position relative to gravity.
- Otolith stimulation affects receptors as fluid moves relative to the receptors.
Inertia of the Fluid
- Fluid inertia in the semicircular canals causes a delay in the response.
- Fluid inertia is detected by the movement of the cupola in the opposite direction.
Central Processing of the Vestibular System
- Vestibular information travels to the vestibular nuclei.
- Information is processed and sent to the cerebellum, extraocular motor nuclei, visceromotor nuclei, and the spinal cord.
- Information from the vestibular nuclei is used for various functions: balance, eye movements, coordinated head and body movements.
Vestibulospinal Connections
- Medial and lateral vestibulospinal tracts carry information to the spinal cord for controlling neck and upper body, and lower limb movements and posture.
Vestibulocochlear
- The vestibular system and the cochlear are integrated at a central nervous level.
Curiosity
- The semicircular canals are relatively smaller in large cetaceans compared with other mammals (including humans).
Meniere's Disease
- A syndrome involving the inner ear marked by episodic vertigo or dizziness.
- Often also marked by tinnitus, fluctuating hearing loss, and fullness or pressure in the ear.
- It is thought that endolymphatic hydrops (fluid imbalance) triggers symptoms.
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Description
Explore the functions and mechanics of the vestibular system in this quiz. Topics include the roles of the utricle and saccule, their responses to gravity and acceleration, and the functioning of cilia within the gelatinous layer. Test your knowledge on this crucial aspect of equilibrium and body orientation.
