Clh&n And Fns Test Iv Fns 19: Vestibular Physiology

Front 1

What are the two types of head movements detected by the vestibular system?

Back 1

Linear and angular acceleration

Front 2

What do the hair cells of maculae aof utricle and saccule detect?

Back 2

Linear (Horizontal and Vertical) acceleration

Front 3

What do the hair cells of crista ampullaris of semicricular ducts detect?

Back 3

Angular or rotational acceleration

Front 4

What are the two types of "hair" found in cristae ampullaris and maculae?

Back 4

Stereocilia and kinocilia

Front 5

What stimulates the hair cells in utricle and saccule?

Back 5

Slow displacement of otoconia

Front 6

What stimulates the hair cells in the crista ampullaris?

Back 6

Semicircular ducts

Front 7

True/False: Hair cells at rest (no bending of hair cell cilium) do not have a basal firing rate.

Back 7

False, they produce a basal discharge of 100 AP/sec.

Front 8

Which is taller, kinocillium or stereocilium?

Back 8

Kinocillium

Front 9

Deflection of cilia TOWARD kinocilium results in what?

Back 9

Maximal depolarization resulting in fewer A.P.s/sec

Front 10

Defleciton of cilia AWAY from the kinocilium results in what?

Back 10

Maximal hyperpolarization resulting in fewer A.P.s/sec

Front 11

Deflection of cilia toward intermediate positions results in what?

Back 11

Submaximal change in hair cell which results in intermediate change (either hyper or de- polarizing)

Front 12

Deflection perependicular to a line drawn from the shortest stereocilia to the kinocilium results in what response?

Back 12

No response

Front 13

What are the otolithic organs?

Back 13

Utricle and Saccule

Front 14

Define: A patch of sensory epithelium containing hair cells in the utricle and saccule

Back 14

Macula

Front 15

Which otolithic organ does the linear acceleration?

Back 15

Utricle

Front 16

Which otolithic organ does vertical acceleration?

Back 16

Saccule (SaVy?)

Front 17

What are the calcium carbonate crystals embedded in an lying on the otolithic membrane called?

Back 17

Otoconia

Front 18

What is the function of the otoconia?

Back 18

It enhances the density of the otolithic membrane improving the movment of the cilia to produce depolarization (Toward) or hyper (Away from)

Front 19

Define: A curved ridge found in both the utricle and saccule that determines the orientation of the cilia of the hair cells.

Back 19

Striola

Front 20

In the Utricle how are hair cell kinocilia aligned?

Back 20

Toward the Striola (U.T. S.A.)

Front 21

In the saccule how are the hair cell kinocilia aligned?

Back 21

Away from the striola (Utricle Toward Saccule Away or UT San Antonio)

Front 22

True/False: Because of the curvature of the striola, the kinocilia are all aligned in the same direction as they were in the cupula?

Back 22

False, the kinocilia are NOT all aligned in the same direction (how would you feel partial movement?)

Front 23

What is the threshould for head tilt?

Back 23

30 degrees

Front 24

How are all three of the semicircular canals oriented to each other?

Back 24

Perpendicular

Front 25

Define: A thickened crest on the inner surface of the ampulla of the semicircular ducts that contain sensory epithelium and is covered by a gelatinous mucopolysaccharide material called cupula.

Back 25

Crista ampullaris

Front 26

True/False: the cupula completely blocks the passage of endolymph.

Back 26

True, this produces a diaphragm like effect

Front 27

True/False: Linear accelerations of the head have no/little effect on the vestibular system.

Back 27

True, linear accelerations of the head produce equal forces on each side of the upula so the cilia are not bent.

Front 28

What are the effects of alcohol on the density of the cupula?

Back 28

It decreases the density resulting in unequal forces in the ducts resulting in misinterpretation of linear acceleration as angular acceleration

Front 29

What happens to the kinocilium in the LHD and the RHD in the event of rotation to the left (hint the cilia in the left duct are deflected toward the kinocilium).

Back 29

Depolarization of the hair cells in the LHD (deflected toward the kinocilium) and hyperpolarization of hair cells in RHD

Front 30

How are all three of the semicircular canals oriented to each other?

Back 30

Perpendicular

Front 31

Define: A thickened crest on the inner surface of the ampulla of the semicircular ducts that contain sensory epithelium and is covered by a gelatinous mucopolysaccharide material called cupula.

Back 31

Crista ampullaris

Front 32

True/False: the cupula completely blocks the passage of endolymph.

Back 32

True, this produces a diaphragm like effect

Front 33

True/False: Linear accelerations of the head have no/little effect on the vestibular system.

Back 33

True, linear accelerations of the head produce equal forces on each side of the upula so the cilia are not bent.

Front 34

What are the effects of alcohol on the density of the cupula?

Back 34

It decreases the density resulting in unequal forces in the ducts resulting in misinterpretation of linear acceleration as angular acceleration

Front 35

What happens to the kinocilium in the LHD and the RHD in the event of rotation to the left (hint the cilia in the left duct are deflected toward the kinocilium).

Back 35

Depolarization of the hair cells in the LHD (deflected toward the kinocilium) and hyperpolarization of hair cells in RHD

Front 36

What is the threshold for dtermining angular motion?

Back 36

Degrees/sec^2

Front 37

Define: When the eyes reach the edge of the orbit, they snap back rapidly in the direction of the rotation to reset to a new central position.

Back 37

Saccade

Front 38

Define: Repetitive slow and quick movments when rotation continues (alternating slow movements followed by rapid saccades).

Back 38

Nystagmus

Front 39

What is the sensory limb of the VOR (vestibular ocular reflex)?

Back 39

Hair cells in semicircular ducts via the vestibular nerve via the vestibular nuclei via MLF to the extraocular cranial nerve motor nuclei

Front 40

What is the efferent limb of the VOR (vestibular ocular reflex)?

Back 40

Extraocular cranial nerve motor nuclei (III, IV, VI) and effectors which are extraocular eye muscles

Front 41

When rotation is stop, do the eyes move in the direction of the previous motion or opposite to it?

Back 41

Opposite to it.

Front 42

Fill in the blank: Nystagmus is always _______ the perceived direction of motion.

Back 42

with

Front 43

What is the Doll's eye maneuver?

Back 43

Rotating an unconscious patient to the right or left and seeing if the eyes coordinately move in the opposite direction.

Front 44

What is a faulty doll's eye maneuver indicative of?

Back 44

Highly indicative of a brain stem injury

Front 45

What is the result of a unilateral labyrinthectomy?

Back 45

Tilting of the head and body to the side o the damage. Reason The basal activity from the intact labyrinth is not balance by comparable leve of activity on the damaged side. This difference is interpreted as motion away from the side of the labyrinthectomy.

Front 46

What are the two types of movements the vestibular system is capable of detecting?

Back 46

Linear and angular acceleration

Front 47

What are the two receptor organs for the vestibular system?

Back 47

Hair cells of maculae of utricle and saccule and hair cells of crata ampullaris of semicircular ducts

Front 48

True or False: Vestibular hair cells fire at a particular basal rate.

Back 48

TRUE

Front 49

Deflection of cilia toward kinocilium results in what?

Back 49

Maximal depolarization

Front 50

Deflection of cilia away from kinocilium results in what?

Back 50

Maximal hyperpolarization

Front 51

What happens when the ciliar are deflected toward intermediate positions?

Back 51

Submaximal de or hyper polarization

Front 52

What happens when the cilia are deflected perpendicular to a line drawn from the shortest stereocilia to the kinocilium?

Back 52

No change in AP firing rates

Front 53

What two structures respond to linear acceleration and static head tilt?

Back 53

Utricle and Saccule

Front 54

Define: Patch of sensory epithelium containing hair cells in the utricle and saccule.

Back 54

Macula

Front 55

Which way is the macula oriented in the utricle?

Back 55

parallel to the ground in a horizontal plane when the head is upright

Front 56

Which way is the macula oriented in the saccule?

Back 56

Located on the medial wall of the saccule and oriented almost perpendicular to the ground in a sagittal plane when the head is upright

Front 57

Which otolithic organ senses horizontal acceleration?

Back 57

Utricle

Front 58

Which otolithic organ senses vertical acceleration?

Back 58

Saccule

Front 59

What is the purpose of the otoconia?

Back 59

Enhance density of the otolithic membrane resulting in more bending of the cilia in response to acceleration

Front 60

Define: calcium carbonate crystals embedded in and lying on the membrane of the utricle and saccule.

Back 60

Otoconia

Front 61

Define: A curved ridge that detemines the orientation of the cilia of the hair cells located in the utricle and saccule.

Back 61

Striola

Front 62

In the Utricle which way are the hair cells aligned in terms of the striola

Back 62

Toward the Striola (UT San Antonio)

Front 63

In the Saccule which way are the hair cells aligned in reference to the striola?

Back 63

Away from the striola (UT San Antonio, Utrice Toward Saccule Away)

Front 64

True/False: due to the curvature of the striola, the kinocilia are all aligned in the sam direction as they were in the cupula.

Back 64

False, the curve of the striola ensures that they are all lined up differently

Front 65

True/False: for each head tilt, some set of hair cells are maximally excited and another set ar maximally inhibited.

Back 65

TRUE

Front 66

What is the threshold when deprived of other sensory input for the static head tilt (gravitational forces)

Back 66

30 degrees

Front 67

What functions to detect angular or rotational acceleration of the head?

Back 67

Semicircular ducts of the semicircular canals

Front 68

True/False: The vestibular system's semicircular canals work independently of each other.

Back 68

False, they work together. Horizontal with horizontal, anterior to posterior, and posterior to anterior.

Front 69

Define: Thickened crest on the inner surface of the ampulla of the semicircular ducts that contains sensory epithelium and the cupula.

Back 69

Crista ampullaris

Front 70

Define: Gelatinous mucopolysaccharide material which overs the crsta ampullaris.

Back 70

Cupula

Front 71

What acts as a diaphragm by extending ot the roof of the semicricular ducs, attaching to eh epithelium lining the duct and completely blocking the passage of endolymph?

Back 71

Cupula

Front 72

Why does angular acceleration result in bending the cilia embedded in the cupula but linear acceleration does not?

Back 72

Linear acceleration produces equal forces on each side of the cupula so the cilia are not bent

Front 73

Why does excessive alcohol consumption affect the cupula?

Back 73

It creates a less dense endolymph from the stria vascularis which results in unequal forces during linear acceleration

Front 74

When the cilia in the left duct are deflected twoard the kinocilium this results in _________ of the hair cells in the LHD and _________ of the hair cells in the RHD.

Back 74

depolarization of hair cells in LHD and hyperpolarization of hair cells in RHD

Front 75

What is the threshold for detection of angular motion?

Back 75

0.1 degrees/sec^2

Front 76

Fill in the blank: The firing rate of the vestibular nerve is _______ to angular velocity.

Back 76

Proportional

Front 77

What functions to allow gaze to remain fixed on a point in space during vertical and horizontal movements of the head?

Back 77

Vestibulo-Ocular Reflex (VOR)

Front 78

Define: When the eyes reach the edge of the orbit, they snap back rapidly in the direction of the rotation to reset to a new central position.

Back 78

Saccade

Front 79

Define: Repetitive slow and quick movements named according to the direction of the fast eye movement (in the direction of the rotation).

Back 79

Nystagmus

Front 80

What are the receptors for the vestibulo-ocular reflex?

Back 80

Hair cells in semicircular ducts

Front 81

Describe the afferent limb of the VOR.

Back 81

Bipolar neurons of vestibular ganglion project through the vestibular nerve to the vestibular nuclei, project to the extraocular cranial nerve motor nuclei via the MLF

Front 82

Describe the efferent limb of the VOR.

Back 82

Extraocular cranial nerve motor nuclei (III, IV, and VI)

Front 83

What is the effector tissue for the VOR?

Back 83

Extraocular eye muscles

Front 84

For the VOR when the head is rotated to the left, which way will the eyes travel?

Back 84

To the right (opposite the direction of motion)

Front 85

Define: A test which is performed in an unconscious patient by rotating the head in one direction and assessing if eyes move coordinately in the opposite direction (VOR).

Back 85

Doll's Eye maneuver

Front 86

Why does a patient with a unilateral labyrinthectomy tilt the head and body to the side of the damage?

Back 86

The basal activity from the intact labyrinth is not balanced by comparable level of activity on the damaged side. This difference is interpreted as motion away from the side of the labyrinthectomy.