PSY313H5 Lecture Notes - Lecture 3: Spinach, Middle Ear, Retinal Detachment

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Published on 11 May 2013
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PSY213 Lecture 3 - Jan 24, 2013
Sensory Aging
exp. some loss of sensitivity as we age
all senses attuned to some source of energy from the environment that is
picked up from specialized recepter cells located in sensory organs (ears, eyes,
nose, etc.)
sensory loss may be caused by deterioration in the nerves/fibres, organs, brain
Age related Changes occur at all levels of a sensory system
sensory system deterioration may be from disease, misuse/disuse of sensory
organs
field study: students made to wear special lenses (vision loss), blockers i ears,
students sent to do everyday things (ex. groceries)
o students became very cautious, fumbling around, etc.
schlerotic coat = sturdy to withstand pressure from within eye (2X
atmospheric pressure) and so the eye can keep its spherical shape
white of eyes are white because the eye is reflecting most of the light that
enters it
pupil responds to emotional, sexual arousal, also light, etc.
retina - captures light energy that leads to nerve signals
two chambers: aqueous: filled with water; vitreus chamber: contains jelly like
substance
muscles connected to lens allow for changing the curvature of lens to
accomodate for different vision
lens flat for visually seeing long distances (6-7 and more metres away); image
blurred when lens is flat and looking at closer objects
muscles change refractory power of eye by increasing curvature of lens
therefore making it able to focus on closer objects; increasing curvature as
objects get closer
near point: smallest point at which you can see an object clearly; lens has
reached its maximum curvature
with age vitreus humour (transparent jelly in vitreus chamber) becomes more
opaque (loses transparency), makes image harder to reach retina at back of
eye
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eye becomes more vulnerable to debris from metabolic processes of eyes,
casts shadow over retina makes you see small shadows (usually doesn't
bother ppl too much b/c gravity brings debris down to settle at bottom of the
eye)
seeing shower of sparkles means retina is at risk of being detached
iris gets smaller; limits amount of light able to get through pupil (b/c pupil gets
smaller)
o limits amount of light able to get in by almost 60-70%
o called: senile meiosis (happens by age 60)
PUPIL RESPONDS MORE SLOWLY WITH AGE
o changes due to weakening of muscles that control the pupil
o eye takes longer to adjust to changes in illumination (ex. driving at
night, leaving a theatre, etc.)
lens gains layers like an onion from birth to get bigger
o older cells in inner core of lens shrivel and harden b/c lose water, lens
become less transparent
o around age 35, lens begins to get yellow; harder to discriminate colour
o lens gets bigger, thicker, harder, and loses its ability to change its shape
(harder to focus properly at short distances)
Presbyopia
o increase in near point distance (notice you have to move objects farther
away just to see them); begins around age 40 (average), women
experience this 3-5 years earlier than men
o condition easily corrected with corrective lenses
o people who already have vision problems (myopia) may need to get
bifocals in their 40s
all physiological factors for vision loss added up do not account for visual
acuity which means that neural parts of the visual system also plays a role
by age 80, visual acuity is at 20% of what is was at age 30
dynamic visual acuity ability to see objects that are moving (ex. reading ad on
bus as its moving)
o mediated by different types of special cells
o visual field shrinks as we get older (horizontal field vision decreases
from 170 degrees to 140 degrees)
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Document Summary

Exp. some loss of sensitivity as we age. White of eyes are white because the eye is reflecting most of the light that enters it. Pupil responds to emotional, sexual arousal, also light, etc. retina - captures light energy that leads to nerve signals two chambers: aqueous: filled with water; vitreus chamber: contains jelly like substance. Muscles change refractory power of eye by increasing curvature of lens therefore making it able to focus on closer objects; increasing curvature as objects get closer. Near point: smallest point at which you can see an object clearly; lens has reached its maximum curvature. With age vitreus humour (transparent jelly in vitreus chamber) becomes more opaque (loses transparency), makes image harder to reach retina at back of eye. All physiological factors for vision loss added up do not account for visual acuity which means that neural parts of the visual system also plays a role.

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