Lecture 5

Question 1

The vestibular system is a sensory
system located in:

Answer 1

the inner ear

Question 2

The vestibular system processes sensory information underlying (3):

Answer 2

➢ Motion
➢ Head position
➢ Spatial orientation relative to gravity

Question 3

The vestibular system is responsible for

Answer 3

the body’s equilibrium

Question 4

The vestibular system is responsible for
the body’s equilibrium; It helps to
stabilize

Answer 4

gaze, head, and postur

Question 5

vestibular system uses specialized sensory neurons __ to transduce physical motion into
neural impulses.

Answer 5

hair cells

Question 6

The vestibular labyrinth composed of two organs:

Answer 6

(1) Otolith organs (Utricle & Saccule)
(2) Semicircular canals (Superior, Posterior & Horizontal)

Question 7

Otolith organs:

Answer 7

Utricle & Saccule

Question 8

Semicircular canals:

Answer 8

Superior, Posterior & Horizontal

Question 9

Vestibular hair cells:

Answer 9

Flask-shaped epithelial cells with a
bundle of hair-like processes
(STEROCILLIA) attached between each
other by a TIP LINK.

Question 10

Vestibular hair cells: kinocillum:

Answer 10

the longest process

Question 11

Hair cell is very sensible to

Answer 11

movement

Question 12

Hair cell is very sensible to movement.
The movement changes

Answer 12

its membrane
potential

Question 13

When the hairs (sterocillia) move toward
Kinocillum =

Answer 13

depolarization (excitation)

Question 14

When the hairs (sterocillia) move far from the
Kinocillum =

Answer 14

hyperpolarization (inhibition)

Question 15

When the sterocillia (hair bundle) is deflected toward
the kinocilium,

Answer 15

tip links are stretched and directly
open K+
-selective channels near the tips of the
stereocilia, allowing K+ to flow into the hair cell and
depolarize the hair cell.

Question 16

The resulting depolarization of the hair cell

Answer 16

opens Ca2+
channels in the cell body, allowing Ca2+ entry and
release of neurotransmitter to excite the post–synaptic
neuron (vestibular nerve) and the electrical signal is
sent to the brain.

Question 17

the hair cell (receptor) is ___ to
the nerve.

Answer 17

not directly attached

Question 18

2 otolith organs:

Answer 18

(1) utricle and
(2) saccule

Question 19

Each otolith organ contains (3) :

Answer 19

(1) Macula
(2) Gelatinous layer
(3) Otolithic membrane

Question 20

Macula:

Answer 20

sensory epithelia containing
the soma (cell body) of hair cells and
supporting cells,

Question 21

Gelatinous layer:

Answer 21

containing hair
bundles

Question 22

Otolithic membrane

Answer 22

Fibrous layer
embedding ‘Otoconia’: crystals of
calcium carbonate (ear rocks, stones).

Question 23

Otoconia

Answer 23

crystals of
calcium carbonate (ear rocks, stones)

Question 24

Otolith organs detect __ movements

Answer 24

linear

Question 25

Otolith organs detect linear movements:

Answer 25

(1) Translational movements of the head (i.e., forward & backward movements)

(2) Static head movement relative to the gravitational axis (i.e., head tilts)

Question 26

The otoconia (ear rocks) make

Answer 26

the otolithic membrane heavier than the
structures and fluids surrounding it.

Question 27

When the head tilts or moves, gravity causes the otolithic membrane to

Answer 27

shift relative to the macula. The hairs in the gelatinous layer are
displaced and a receptor potential is generated.

Question 28

The utricle is positioned

Answer 28

horizontally

Question 29

The utricle detects:

Answer 29

the horizontal translational movements of the head
(i.e., moving forward or backward = moving in X axe):
➢ e.g., walking, being in a moving car.

Question 30

The saccule is positioned

Answer 30

vertically

Question 31

The saccule detects

Answer 31

the vertical translational movements of the head
(i.e., moving up & down = moving in Y axe):
➢ e.g., being in a moving elevator.

Question 32

Semicircular canals

Answer 32

Fluid-filled tubes specialized for
responding to rotations of the
head.

Question 33

3 semicircular canals:

Answer 33

(1) Horizontal
(2) Superior
(3) Posterior

Question 34

Horizontal semicircular canal:

Answer 34

turning left & right (No sign)

Question 35

superior semicircular canal:

Answer 35

nodding up & down (Yes sign)

Question 36

posterior semicircular canal:

Answer 36

tilting to a side (towards the shoulders)

Question 37

Semicircular canals: AMPULLA:

Answer 37

an enlargement at the base of each
semicircular canal. It houses the hair cells.

Question 38

Semicircular canals: the hair bundles extend out into a gelatinous mass,

Answer 38

the cupula

Question 39

semicircular canals: endolymph fluid:

Answer 39

circulates in the
semicircular canal.

Question 40

semicircular canals: the rotation of the head causes the movement of the:

Answer 40

endolymph fluid in the
opposite direction of the head movement,
which pushes the cupula and displaces the
hair bundles. As a result, the hair cell is
depolarized and receptor potential is
generated, the electrical signal sent to the
brain.

Question 41

Each semicircular canal works in

Answer 41

opposite manner with its pair
located on the other side of the
head

Question 42

A tilt of the head to one side
(e.g. right) activates the hair
cells in the

Answer 42

right horizontal
canal but inhibits the hair cells
in the left horizontal canal

Question 43

slide 14 15

Question 44

The Vestibulo-Ocular
Reflex (VOR) produces

Answer 44

eye
movements that counter
head movements (i.e.,
moving the eyes in opposing
direction to the head), thus
permitting the gaze to
remain fixed on a particular
point: