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PAPER 2
HOMEOSTASIS
the eye
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Created by
ifrah
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Cards (30)
What is the first structure that light meets when it enters the eye?
The
cornea
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Why is the cornea transparent?
To allow all
light
to pass through
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What is the function of the cornea?
To
refract
or bend light
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What is the iris?
The colored part of the eye that controls
pupil
size
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What is the pupil?
A gap in the middle of the
iris
that allows light to pass through
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How does the lens differ from the cornea?
The lens can change its shape to control light
refraction
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What is the role of the retina?
To detect light and generate
impulses
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What is the function of the optic nerve?
To transmit
impulses
from the
receptor cells
to the brain
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What happens to the pupil in bright light conditions?
The pupil
constricts
to allow less light in
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What is the purpose of the iris reflex?
To protect the
retina
from damage due to
bright light
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What are the two types of muscles in the iris?
Circular muscles
and
radial muscles
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How do circular muscles affect the pupil size in bright light?
They
contract
to make the pupil
smaller
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What happens to the radial muscles in low light conditions?
They contract to pull the
pupil
open
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What are the steps involved in the iris reflex?
In bright light,
circular muscles
contract, and
radial muscles
relax, constricting the
pupil
.
In low light, circular muscles relax, and radial muscles contract, dilating the pupil.
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What is the main purpose of the iris reflex?
To control the
amount
of light entering the eye
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What is the effect of the iris reflex on vision in different lighting conditions?
It helps to protect the
retina
and improve visibility
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What are the important parts of the eye involved in accommodation?
The
cornea
,
lens
,
ciliary muscles
, and
suspensory ligaments
.
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How does the shape of the lens change for nearby objects?
The lens becomes short and fat to
refract
light more strongly.
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What happens to the ciliary muscle when focusing on nearby objects?
The ciliary muscle contracts and moves inwards towards the
lens
.
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What is the role of the suspensory ligaments in accommodation?
They attach the lens to the
ciliary muscle
and can be slackened or taut.
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How does the lens adjust for distant objects?
The lens is stretched out to reduce its
curvature
and
refractive
power.
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What is long-sightedness medically known as?
Hyperopia
.
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What is the problem in long-sightedness?
The
lens
cannot refract enough light, causing images to appear blurry.
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How do glasses help long-sighted individuals?
They contain
convex lenses
that provide extra
refracting power
.
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What is short-sightedness medically known as?
Myopia
.
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What issue arises in short-sightedness?
The
lens
refracts
light too much, causing distant images to appear blurry.
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How do glasses assist short-sighted individuals?
They contain
concave lenses
that counteract the
over-refraction
of the lens.
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What are the differences between hyperopia and myopia?
Hyperopia
(long-sightedness):
Can see
distant
objects clearly.
Difficulty focusing on
nearby
objects.
Corrected with
convex
lenses.
Myopia
(short-sightedness):
Can see
nearby
objects clearly.
Difficulty focusing on
distant
objects.
Corrected with
concave
lenses.
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when focusing on a near object
ciliary muscles
contract
and have a smaller diameter
suspensory ligaments
relax/loosen
lens thickens and refracts light less strongly
when focusing on a distant object
cillary
muscles relax
suspensory
ligaments are pulled tight
lens is pulled thin and refracts light less strongly