Physiology of Vestibular System Quiz

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Questions and Answers

What is the main function of the vestibule system?

To provide information about the motion and position of the body in space (correct)

To regulate blood pressure

To control body temperature

To provide information about sound waves

What is the composition of the inner membranous labyrinth?

Filled with blood

Filled with cerebrospinal fluid

Filled with perilymph

Filled with endolymph (high K+, Ca2+ low Na+) (correct)

What is the function of the maculae or otolithic organs?

To provide information about the position and motion of the body (correct)

To detect sound waves

To regulate blood sugar levels

To control eye movements

What is the function of the semicircular canals?

To provide information about rotational movements Signup and view all the answers

What is the structure of a single hair cell?

30-150 small hairs and 1 kinocilium Signup and view all the answers

What is the function of the tip links in a hair cell?

To connect the kinocilium to the nearest longest stereocilium Signup and view all the answers

What is the composition of the gelatinous layer?

Mucopolysaccharide with calcium carbonate crystals Signup and view all the answers

What is the function of the vestibular reflexes?

To regulate eye movements Signup and view all the answers

What is the primary function of the semicircular canals?

To inform the CNS of the plane and direction of rotation of the head Signup and view all the answers

When rotation is stopped, a person may experience:

A false sensation of spinning with respect to the surroundings Signup and view all the answers

Fibers from the maculae and cristae ampullaris pass to the:

Ipsilateral vestibular nucleus Signup and view all the answers

What is the role of the reticular formation in maintaining equilibrium?

To regulate the tone of various muscles through the stretch reflex Signup and view all the answers

What type of receptors contribute to the sense of equilibrium?

Visual, auditory, and proprioceptive receptors Signup and view all the answers

When the stereocilia bend towards the kinocilium, what occurs?

Excitation of the hair cell Signup and view all the answers

What is the function of the cristae ampullaris?

To detect rotation in its own plane Signup and view all the answers

What is the function of the maculae?

To detect linear acceleration Signup and view all the answers

What is the function of the utricle?

Detect horizontal acceleration Signup and view all the answers

Which part of the hair cell is responsible for bending during movement?

Stereocilia Signup and view all the answers

What is the direction of the hair cells in the utricle?

Pointing upwards Signup and view all the answers

What is the purpose of the vestibular system?

To maintain balance and equilibrium Signup and view all the answers

What is the fluid that fills the inner membranous labyrinth?

Endolymph Signup and view all the answers

What is the direction of the anterior and posterior semicircular canals?

Both are vertical Signup and view all the answers

What is the structure that detects rotational movement in the semicircular canals?

Crista ampullaris Signup and view all the answers

What is the sequence of events that occurs when the head is tilted?

Bending of stereocilia, change in rate of discharge, stimulation of muscles to restore equilibrium Signup and view all the answers

Study Notes

Anatomy of the Inner Ear

The inner ear consists of the cochlea (sensory organ for hearing), vestibule (provides information about motion and position of the body in space), and semicircular canals.
The vestibule is composed of the outer bony labyrinth filled with perilymph and the inner membranous labyrinth filled with endolymph (high K+, Ca2+, low Na+).

Utricle and Saccule (Maculae or Otolithic Organs)

Located on the floor of the utricle and on the wall of the saccule.
Consist of:
- Columnar epithelial cells
- Hair cells (each with 30-150 small hairs and one large cilium called the kinocilium)
- Gelatinous layer with calcium carbonate crystals (otoliths)
- Supporting cells
The bases of hair cells synapse with afferent fibers of the vestibular branch of the 8th cranial nerve.

Functions of the Utricle and Saccule

Utricle: detects horizontal acceleration, head tilt, and low-frequency vibration.
Saccule: detects vertical acceleration.

Semicircular Canals

Three semicircular canals: anterior, posterior, and external (or lateral).
Each canal detects rotation in its own plane and is stimulated by rotational movement (angular acceleration) of the head.
The canals inform the CNS of the plane and direction of rotation of the head.

Neural Connections of the Vestibular Apparatus

Fibers from the maculae and cristae ampullaris pass as the vestibular nerve to the medulla to synapse in the ipsilateral vestibular nucleus.
Connections to the cerebellum, motor cranial nuclei of cranial nerves 3, 4, and 6, reticular formation, and spinal cord.

Other Receptors Contributing to Equilibrium

Visual and auditory receptors
Proprioceptors in muscles
Cutaneous pressure receptors (provide information concerning the direction of support)

Vertigo and Nystagmus

Vertigo: the false sensation of spinning with respect to the surroundings when rotation is stopped.
Nystagmus: abnormal eye movements seen in vertigo.

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Description

Test your knowledge of the vestibular system, including the structure and function of the membranous labyrinth, receptor mechanisms, and transduction mechanisms. Learn about the otolith organs and more.