8.4 Equilibrium and orientation Flashcards

1
Q

What are the two main parts for maintaining quilibrium and orientation

A

Vestibular apparatus: equilibrium receptors maintains our orientation and balance

  • > vestibular receptors: monitors static equilibrium or linear acceleration
  • > semicircular canal receptors: monitors dynamic equilibriium or angular acceleration
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2
Q

what is the vestibule

A
  • suspended in its perilymph are two sacs: saccule and utricle
  • these sacs house equilibrium receptors called maculae that respond to gravity (linear acceleration) and changes in the position of the head
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3
Q

describe the maculae

A
  • sensory receptors for static equilibrium and linear acceleration
  • each hair cell has stereocilia and kinocilium embedded in the otolithic membrane
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4
Q

Describe the Otolithic membrane

A
  • jellylike mass studded with tiny CaCO3 stones called otoliths (dense structures that interact with hair cells)
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5
Q

what are the hair cells that respons to movement in the maculae

A

Utricular hairs respond to horizontal movement (running)

Saccular hairs respond to vertical movement (jumping)

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6
Q

describe utricular receptor cells

A

Otolithic movement in the direction of the kinocilia causesdepolarizes vestibular nerve fibers

Movement in the opposite direction causes hyperpolarizes vestibular nerve fibers

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7
Q

describe saccular receptor cells

A

At rest: about 10% of ion channels are open, and topic signal sent by sensory enuron

excitation: hair cell bends in one direction causing cell to depolarize -> inc action potential frequency in associated sensory neuron
inhibition: if hair cells bend in opp direction, ion channels close, hyperpolarization and sensory neuron signals decrease

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8
Q

describe semicircular canals

A
  • respond to angular acceleration (rotation)
  • lie in the 3 spaces of space and ocmmunicate with the utricle
  • ampulla is swollen end of each canal and houses equilibrium receptors in a region called crista ampullaris
  • receptors respond to angular movements of head
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9
Q

role of crista ampullaris in dynamic equilibrium

A
  • senses iff types of movement
  • Posterior: head tilt left and right

Anterior canal/superior canal: nod yes

Lateral canal/horizontal canal: head shake no

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10
Q

Describe rotary head movement

A
  • head head turns right, endolymph shes the cupula to left

*fluid and cupula move in the same direction

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11
Q

how is vestibular input processed

A
  • vestibular apparatus -> vestibular branch of nestibulocochlear nerve -> cerebellum (imp balance)
  • vestibular apparatus -> vestibular branch of nestibulocochlear nerve -> vestibular nuclei of medualla -> reticular formation -> thalamus -> cerebral cortex
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12
Q

how is balance and oreintation maintained?

A

Vestibular receptors

Visual receptors

Somatic receptors

  • these receptors allow our body to respond reflexively
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