quiz 3

Created by dsherwyn 

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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

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