Lecture 26: Vestibular System

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

<p>Stereocilia return to their resting position. (C)</p> Signup and view all the answers

<p>Sensing motion and maintaining postural stability (A)</p> Signup and view all the answers

<p>Otolith organs and semicircular canals (B)</p> Signup and view all the answers

<p>Stereocilia moving towards the kinocilium (A)</p> Signup and view all the answers

<p>It decreases the firing rate of afferent neurons (C)</p> Signup and view all the answers

<p>They sense linear acceleration and gravity (B)</p> Signup and view all the answers

<p>Short hairs tip towards tall hairs, stimulating nerve activity (D)</p> Signup and view all the answers

<p>Open calcium (Ca2+) channels (D)</p> Signup and view all the answers

<p>Motion sickness (D)</p> Signup and view all the answers

<p>Detecting angular head acceleration (A)</p> Signup and view all the answers

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

<p>Housing hair cells that detect fluid motion (C)</p> Signup and view all the answers

<p>They create a push-pull mechanism in response to motion (C)</p> Signup and view all the answers

<p>Fluid imbalance in the membranous labyrinth (A)</p> Signup and view all the answers

<p>Increased discharge rate of the afferent nerve (C)</p> Signup and view all the answers

<p>Both use hair cells as motion detectors (C)</p> Signup and view all the answers

<p>Low in potassium, high in sodium (A)</p> Signup and view all the answers

<p>The utricle lies horizontally, and the saccule is oriented vertically. (B)</p> Signup and view all the answers

<p>Linear acceleration and head position changes relative to gravity. (C)</p> Signup and view all the answers

<p>To provide shear force to hair cells during linear acceleration. (C)</p> Signup and view all the answers

<p>Utricle hair cells are oriented towards the striola, while saccule hair cells are oriented away from it. (B)</p> Signup and view all the answers

<p>Both use hair cells to detect motion. (C)</p> Signup and view all the answers

<p>Excitation of hair cell activity. (D)</p> Signup and view all the answers

<p>It divides the macula into regions with different hair cell polarities. (C)</p> Signup and view all the answers

<p>3 - 30 µm. (D)</p> Signup and view all the answers

The vestibular system senses head motion, maintains posture, and stabilizes vision during head movement.

Sensory cells in the inner ear that detect head movement by detecting hair bundle deflection.

Occurs when stereocilia move towards the kinocilium, increasing neurotransmitter release.

Occurs when stereocilia move away from the kinocilium, decreasing neurotransmitter release.

Part of the vestibular system detecting rotational head movement.

Part of the vestibular system, detecting linear acceleration and head position relative to gravity.

Nerves that carry signals from vestibular hair cells to the brainstem.

Constant signal from hair cells, which occur even without head motion.

Results from potassium (K+) flowing into the cell, caused by stereocilia deflection towards the kinocilium, opening K+ channels.

Caused by potassium (K+) flowing out of the cell, due to stereocilia deflection away from the kinocilium, thus closing K+ channels.

Located at right angles (orthogonal) to each other.

Increases when stereocilia bend towards the kinocilium, causing depolarization and neurotransmitter release.

Occurs due to stereocilia bending away from the kinocilium, causing hyperpolarization and less neurotransmitter release.

The utricle is oriented horizontally within the inner ear.

The saccule is oriented vertically within the inner ear.

Otoliths are small calcium carbonate crystals that detect linear acceleration and head position relative to gravity.

Each otolith organ has a sheet of hair cells (macula) embedded in a gelatinous mass with otoliths.

Utricle hair cells are oriented towards the striola, a central stripe that divides the macula.

Saccule hair cells are oriented away from the striola.

The striola determines the direction of hair cell excitation and inhibition, making otolithic organs sensitive to linear motion in multiple directions.

Both are inner ear sensory organs using hair cells, but otolith organs detect linear acceleration and head position, while semicircular canals detect rotational movement.

Endolymph is a fluid with high potassium (K+) and low sodium (Na+) concentration found within the membranous canals of the vestibular system.

Perilymph is fluid with low potassium (K+) and high sodium (Na+) concentration found in the space between the membranous canal and bony canal.

The ampulla is a bulge in each semicircular canal containing hair cells (crista ampullaris) and a gelatinous structure (cupula) that senses endolymph movement.

When endolymph moves due to head rotation, the cupula deflects, causing hair cell stereocilia to move towards or away from the kinocilium, altering neurotransmitter release.

Each canal has a counterpart on the opposite side of the head, working as a push-pull system. Rotation in one direction excites one pair, while inhibiting the other.

They share a common fluid system (membranous labyrinth), rely on hair cell motion detectors, and are both innervated by the 8th cranial nerve.

Both hearing and balance can be affected due to the shared fluid system, potentially leading to disorders like Meniere's Disease.

Both use hair cells as motion detectors, functioning on nearly identical principles to sense either sound waves or head movement.