Exam 2: Lab 6 Vision and Hearing Tests Flashcards
20/20
When you are 20 feet away, you see what
______________________
the average person sees from 20 feet away
- average vision
20/40
When you are 20 feet away, you see what
______________________
the average person sees from 40 feet away
- worst than average vision
20/10
When you are 20 feet away, you see what
__________________
the average person sees from 10 feet away
- better than avg vision
Visual acuity
visual sharpness
- how well you can clearly distinguish two closely spaced object
Near Point of vision
- amount of elasticity in the lens
- cornea (transparent) transmit light to middle of iris where pupil is and behind it is the lens
- distance at which object first appears blurred
job of the lens
- precisely focus the light on to the retina where the photoreceptors are
as we get older suspensory ligaments of eye
- smooth muscles that control the shape of the lens
- less elasticity in the lens, harder for muscle to change the shape
Tests of the extrinsic eye muscles
- 6 of them
- there to hold the eye in place and control eye movementss
- test convergence of eye
- eye should move medially to converge on object as it is slowly brought to the bridge of nose
nystagmus
- unwanted eye movement
- could be cause by weak extrinsic eye muscle
Pupillary reflex
- check to see if there’s constriction/dilation or no movement
(dim light/pen light) - change in pupil size and measure pupil diameter
why do pupillary reflex..what is it indicative of?
- indication of brain damage (brain intact)
- hind brain
- occipital lobe responsible for eye movement
demonstration of blind spot
- optic disc - axons where the neurons from the retina converge and become the optic nerve behind it
- cant perceive that light; always there
Binocular rivalry
- humans have binocular vision
- certain field of vision in each eye - overlaps
- gives us depth perception
- hunters front (overlap vision/3D vision)
- how what one eye sees affect what another eyes sees
Color blindness tests
- male more prone x (female) chromosomes expressed
- natural light
- cant see color - indicate type of color blindness
2 types of deafness
- conduction deafness
- sensory deafness
conduction deafness
- happen when there’s damage from the middle ear (ossicles) to outer ear (includes oracle)
- can wear hearing aid; hear vibration through temporal bone
job of oracle
is to capture sound
tympanic membrane
- eardrum
- boundary between middle ear and outer ear
- transmit vibration from outer ear to inner ear
ear path
oracle (pinna) to external auditory meatus to tympanic membrane to maleus to incus to stapes to oval window
middle ear
- ossicles
- malleus in contact with tympanic membrane
- vibration
oval window
- boundaries between middle ear and inner ear
inner ear
- cochlea
- vestibules (semi-circular canal)
cochlea
hearing
vestibular apparatus
- semi-circular canal
balance
conduction damaged caused by
- most infection: in middle ear
- ear wax
- damage in oracle
sensory deafness
- results from damage from cochlea to inner ear
- cochlea connected to brain (Cranial Nerve 8 or temporal lobe)
- vibration can’t be processed (mastoid process)
cause of sensory deafness
- anything that can kill hair cells (modified epithelial; don’t regenerate;)
what damages hair cells
- excessively loud noises (prolonged loud noises)
- explosions
- dj/rock band member
inner ear infection
- balance problem
- hurts
- dizzy
how is sound localized; where it is coming from
- how does brain perceive?
- difference in the time of arrival of the sound in each ear
- difference in the loudness of the sound in each ear
- higher frequency of action potential sent
