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47 terms

quiz 3

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saccades
rapid jumping eye movements
smooth pursuit
smooth eye movement that tracks an object
vergence
eyes move toward or away from each other
vergence (convergent)
eyes move toward eachother
vergence (divergent)
eyes move away from eachother
Vestibulo-ocular reflex (VOR)
eye movement using smooth pursuit to track an object
Optokinetic nystagmus
eyes start to shake when looking far left
superior colliculus is affected by __
several cortical and subcortical sites
superior colliculus
activates certain movement
general functions of the vestibular system
1. contribute to sense of movement and balance
2. stabilize vision during head movement (VOR)
3. regulate postural tone
specific functions of vestibular system
transduction of angular/linear velocities & accelerations and transduction of the gravitational vector
vestibular system is housed in the __
inner ear
vestibule
main body of vestibular system, continuous with cochiea
cochela
auditory receptor. sound waves get converted to action potentials
purpose of semicircular canal
transduce angular accelerations of the head
3 types of semicircular canals are:
horizontal, posterior, and anterior/superior
horizontal semicircular canal
used in "no" motion
posterior semicircular canal
used in "yes" motion
anterior/superior semicircular canal
used in "don't know" (shrugging shoulders) motion
semicircular canals are filled with ___
endolymph
cupula
gelatinous structure that interrupts fluid flow and is inside the ampulla
ampulla
widest region of semicircular canal
hair cells that extend into the cupula ___
transform mechanical energy into neural activity
hair cells in cupulas are composed of ___ and ___
many stereocilia and one kinocilium
when stereocilia are pushed towards the kinocilium the hair cell ___
depolarizes
when stereocilia are pushed away from the kinocilium the hair cell __
hyperpolarizes
excitation
stereocilia is pushed towards kinocilium in the left semicircular canal
inhibition
stereocilia is pushed away from kinocilium in the right semicircular canal
purpose of otolith organs
transduce linear accelerations of the head
utricle
horizontal linear acceleration
saccule
vertical linear acceleration
otoliths
carbonate crystals embedded into macula
normal vestibular function relies on the equivalent densities (or specific gravity) of ___ and ___
endolymph and cupula
cutaneous receptors that receive information regarding pressure
merkel's discs and pacinian corpuscle
proprioception
knowledge of body position in space
sensory receptors of proprioception are:
muscles, tendons, and joints
muscle spindles
tell you length of skeletal muscles in your body
golgi tendon organs : "GTO's"
sensitive to changes in muscle force/tension - activated when muscle is contracted (firing rate increases w/greater tension)
dorsal roots carry __
afferent AP's to CNS via dorsal horn
ventral roots carry __
efferent AP's to effector organs
primary somatosensory cortex
proprioceptive and cutaneous information ascends in afferent tracts in spinal cord and projects to sensory and parietal cortex
somatotopic organization
amount of cortical tissue devoted to each body surface proportional to sensitivity of that part
reflexes
rapid, involuntary, and predictable responses to stimuli
reflex arc
direct route from sensory neuron to an effector organ
latency
app. 75 ms
4 factors affecting latency
1. length of pathway
2. # of synapses
3. myelin
4. axon diameter
eye movements are controlled in the ___
brainstem