EXAM
How are sounds transmitted to the brain? - ANSWERS-Sensory neurons
form a cochlear nerve which synapses in the medulla, cerebrum,
midbrain and thalamus which then travels to the auditory cortexes. At
the medulla signals cross so that autodity signals from both ears are
delivers to both sides of the brain.
What do we call hearing loss due to damage in the nerve/brain pathway?
- ANSWERS-Central hearing loss
What are the two components of the vestibular apparatus? What does
each one tell us about head position? - ANSWERS-Otolith organs
(Utricle and Saccule): linear acceleration and static position
Semicircular Canals (superior, horizontal, posterior): rotational
acceleration
What is the macula (ear)? - ANSWERS-The sensory mechanism for
otolith organs including the otolith membrane, hair cells and supporting
cells
How are hair cells organized on the utricle and saccule? - ANSWERS-
Uticle: on a horizontal plane, hairs stand upright
Saccule: on a vertical plane, hairs are sideways
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EXAM
How do the otolith organs use gravity for determining position? -
ANSWERS-Otolith crystals (calcium carbonate) si on top of hair cells.
When the head moves gravity works on the otolith crystals causing
displacement of hair cells. TIlting head forward does not release NT
while tilting head backwards does.
What is the Crista? - ANSWERS-Sensory mechanism for the
semicircular canals including cupula, hair cells and supporting cells
What are the semicircular canals filled with? - ANSWERS-endolymph
What is the cupula? - ANSWERS-pliable gelatinous mass embedded in
stereocilia blocking the passage of endolymph in the canals.
How are hair cells in the semi circular canals activated? - ANSWERS-
Fluid movement due to head rotation pushes against the cupula which
moves that hair cells and dictates head position by the direction of hair
cell movement
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EXAM
How is head position communicated with the brain? - ANSWERS-Hair
cells synapse with vestibulocochlear nerve and signals are taken to both
the cerebellum and medulla. From the medulla signals are sent to the
cerebral cortex where the information can be used to assist eye
movement while head is turning.
How does the vestibular system contribute to vertigo? motion sickness?
Meniere's disease? - ANSWERS-Vertigo - unexpected or mis-matched
inputs from vestibular system resulting in spinning feeling
Motion sickness - unfamiliar movement patterns
Meniere's - excess endolymph causing changes in pressure and
perception of movement
What wavelength is visible light? - ANSWERS-400-700 nm
Define reflection and refraction. - ANSWERS-reflection occurs when
wave strikes an object and bounces off it. refractions is bending of wave
caused by change in its speed as it moves from one medium to another
What are the components of the external eye? - ANSWERS-scalera wall,
facial bones, muscles, tear ducts
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EXAM
What does the outer component of the inner eye consist of? -
ANSWERS-cornea, lens, aqueous humour, cornea, iris, pupil, cilliary
muscle
What is the purpose of the iris and pupil? - ANSWERS-Iris - smooth
muscle that controls pupil size
Pupil - regulates amount of light let into inner eye
What does the ciliary muscle control? - ANSWERS-the shape of the lens
What does the inner component of the inner eye consist of? -
ANSWERS-vitreous body, sclera lined with retina, retina, optic disc,
fovea
What structure divided the inner and outer portions of the inner eye? -
ANSWERS-The lens
What is the optic disc? - ANSWERS-Also known as the blind spot, is
the area where the optic nerve and blood vessels leave the eye
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