BSC 215 Lecture Notes - Lecture 35: Semicircular Canals, Vestibular System, Saccule

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silvercicada472

11 Jun 2018

School

University of Alabama

Department

Biological Sciences

Course

BSC 215

Professor

Jason Pienaar

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Equilibrium

The vestibule lies between the semicircular canals and the cochlea. It

contains two bulblike sacs, the saccule and utricle, whose membranes are

continuous with those of the cochlea and semicircular canals, respectively.

The saccule and utricle contain receptors that help maintain equilibrium.

Equilibrium is maintained in response to two kinds of motion:

• Static equilibrium maintains the position of the head in response to

linear movements of the body, such as starting to walk or stopping.

• Dynamic equilibrium maintains the position of the head in response to

rotational motion of the body, such as rocking (as in a boat) or

turning.

The perception of equilibrium occurs in the vestibular apparatus. Motion in the following two

structures is detected as follows:

• The vestibule is the primary detector of changes in static equilibrium.

A sensory receptor called a macula is located in the walls of the

saccule and utricle, the two bulblike sacs of the vestibule. A macula

contains numerous receptor cells called hair cells, from which

numerous stereocilia (long microvilli) and a single kinocilium (a true

cilium) extend into a glycoprotein gel, the otolithic membrane. Calcium

carbonate crystals called otoliths pervade the otolithic membrane,

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Document Summary

The vestibule lies between the semicircular canals and the cochlea. It contains two bulblike sacs, the saccule and utricle, whose membranes are continuous with those of the cochlea and semicircular canals, respectively. The saccule and utricle contain receptors that help maintain equilibrium. The perception of equilibrium occurs in the vestibular apparatus. Motion in the following two structures is detected as follows: the vestibule is the primary detector of changes in static equilibrium. A sensory receptor called a macula is located in the walls of the saccule and utricle, the two bulblike sacs of the vestibule. A macula contains numerous receptor cells called hair cells, from which numerous stereocilia (long microvilli) and a single kinocilium (a true cilium) extend into a glycoprotein gel, the otolithic membrane. Calcium carbonate crystals called otoliths pervade the otolithic membrane, increasing its density and thus its responsiveness to changes in motion.

Related Questions

The ____________ contains vertically arranged maculae that would provide feedback of body movement in the vertical plane.
The ____________ are stimulated during linear acceleration in the transverse plane.
An example of ____________ would include sitting in a wheeled chair and having someone push you from behind.
An example of ____________ would be sitting in a chair and having someone spin you in a circle.
Each of the ____________ is specially positioned to detect angular acceleration in one of the three planes.
When someone is standing still, the kinocilia of the macula sacculi are bending inferiorly and thus conveying information regarding one's ____________ .
The concept of ____________ can be exemplified by any acceleration, or change in velocity.

static equilibrium
dynamic equilibrium
macula utriculi
saccule
vestibule
semicircular canals
cochlea
crista ampularis
linear acceleration
utricle
otolithic membrane
angular acceleration
macula sacculi

ivoryraven299

1. Any object moving through space (such as an animalâs head)has six degrees of freedom. Three of these aretranslational. This means that motion canoccur along the x-, y-, or z-axis. Simply put, this means movingforwards or backwards, moving sideways, ore moving up and down. Theremaining three degrees of freedom arerotational, i.e. roll, pitch, and yaw.The primary sensory input for motion of the head is enabled bythe

left and right retina in combination with cranial nerve pairII

left and right vestibular apparatus in combination with cranialnerve pair VIII

2. Translational motion is detected by the neuroepithelia ofthe

otolith organs

ampullae within the semicircular canals

3. Rotational motion is detected by the neuroepithelia ofthe

otolith organs

ampullae within the semicircular canals

4. Recall that the vestibulo-ocular reflex enables the eyes toremain fixed on target and that extrinsic eye muscles areinnervated by brainstem Î±-motor neurons. What role does the mediallongitudinal fasciculus play in the vestibulo-ocular reflex?

central integration

links the vestibular nuclei with brainstem motor nuclei

5. Descending projections from the vestibular nuclei enablepostural adjustments of the head and body. Any stereotypical changein head position that promotes balance ismediated by the vestibulo-cervical reflex. This name stems from thefact that most of the Î±-motor neurons that control the position ofthe head are located in the motor nuclei of the

brainstem

cervical cord

6. Any stereotypical change in bodyposition that promotes balance is mediated by thevestibulo-spinal reflex. Does this reflex implement the Î³-loop?

yes

periwinkletrout278

1. Which of the following represents the most likely location of sensory receptors that monitor internal body temperature and serum osmolarity?

a. Carotid bodies

b. Hypothalamus

c. Solitary nucleus

d. Nucleus ambiguus

e. Anterolateral medulla

2. A reduction in activity in the fibers ascending in the lateral lemniscus to the inferior colliculus that would contribute to changes in peak IV of the auditory brain response (ABR) would not be related to damage to which of the following structures?

a. Anterior cochlear nucleus

b. Posterior cochlear nucleus

c. Medial superior olivary nucleus

d. Lateral superior olivary nucleus

e. Medial geniculate nucleus

3. The peripheral receptors of the vestibular system lie in five separate organs for each inner ear, including three semicircular canals and two otolith organs. The three semicircular canals are responsible for the transduction of what?

a. Linear accelerations of the head in the horizontal plane

b. Rotational head motion

c. Tilts of the head relative to gravity

d. Static head position

e. Up-down head motion aligned with gravity

4. The receptor cells of the vestibular system are termed hair cells. Signal transduction in the hair cell results from a cascade of several events. Initially, when movement occurs, stereocilia are deflected. For excitatory signal transduction in hair cells, which of the following series of events is correct?

a. The stereocilia are compressed toward the cell surface by acceleration forces, K+ channels in the stereocilia close, Ca2+ channels in the basolateral cell membrane close, and excitatory neurotransmitter is released

. b. The stereocilia are bent away from the kinocilium, K+ channels in the stereocilia close, Ca2+ channels in the basolateral cell membrane close, and excitatory neurotransmitter is released.

c. The stereocilia are rigid and do not move, endolymph motion forces the K+ channels in the stereocilia open, Ca2+ channels in the basolateral cell membrane close, and excitatory neurotransmitter is released.

d. The stereocilia are bent toward the kinocilium, K+ channels in the stereocilia open, Ca2+ channels in the basolateral cell membrane open, and excitatory neurotransmitter is released.

e. The stereocilia are bent perpendicular to the kinocilium, K+ channels in the stereocilia close, Ca2+ channels in the basolateral membrane open, and excitatory neurotransmitter is released.

5. Which of the following innervates the superior, medial and inferior rectus muscles of the eye and is a constrictor of the pupil?

a. Trochlear

b. Abducens

c. Oculomotor

d. Trigeminal

e. Facial

BSC 215 Lecture Notes - Lecture 35: Semicircular Canals, Vestibular System, Saccule

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