Download Eye Structure and Function Guided Notes Name: Do Now Which

Eye Structure and Function Guided Notes
Name: ________________________
Do Now
Which ‘fact’ is false?
1) Your eye muscles are the most active muscles in your body.
2) Newborns don’t produce tears
3) Corneal scratches heal in about 48 hours.
4) If you sit too close to a TV , computer, or tablet, you will damage your eyes.
External Eye and Accessory Structures
__________________________refers to
tears. Tears __________ and
_________________ the eyes, and also
__________________________.
The lacrimal ducts empty into the nasal
cavity
This is why nose and eye irritation is often
linked.
•
you get the sniffles if cry and
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you get watery eyes if congested
___________________ are the membranes the line the eyelid and eyeball.
__________________ inflammation of these membranes, caused by irritants, allergies, or infection (e.g. “pink eye”).
Extrinsic Eye Muscles
Control movement of the eyes. Remember: rectus = straight, oblique = slanting
Eye muscle names and actions
Name
Action
Lateral rectus
Medial rectus
Superior rectus
Inferior rectus
Inferior oblique
Superior oblique
Eyeball
The eye has three ______________________, or coats.
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_______________________ – “whites of the eye” , outermost, thick connective tissue.
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_______________________ – has blood vessels, middle layer
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_______________________ – contains the photoreceptors (rods & cones), inner layer
The eye is divided into two fluid-filled chambers:
•
The anterior chamber is filled with ________________________________________
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The posterior chamber is filled with ______________________________________
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Both fluids ________________________________, and the aqueous humor
_________________________________________.
_______________________________ occurs when the aqueous humor doesn’t drain properly, resulting in
increased eye pressure and blindness
Pathway of Light
1. Light enters the eye at the ________________________ – a clear, hard part of the sclera.
Functions: protects eye and focuses light
Fun fact: the cornea is responsible for ~70% of the eye’s focusing ability
2. Light passes through the ______________________ which is the opening in front of the lens.
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•
The size of the pupil is controlled by the muscles of the __________ (the
the eye).
colored part of
The pupil dilates or contracts to vary the amount of light hitting the retina.
3. The light passes through the ______________which focuses the light onto the retina.
•
4.
The __________________________ are muscles which change the shape of the lens to focus on
nearby items, a process called __________________________.
The light passes through the _________________________ to land on the retina, which contains the
photoreceptors.
There are no photoreceptors on the _____________________________, which is where the optic nerve exits
the eye – this causes a small blind spot.
Photoreceptors
Rods
Responsible for night and peripheral vision –
•
more abundant
that’s why colors seem to be lost in the dark.
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sensitive to ______________________________
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do not discriminate _______________________________________________
Cones - ________________________________________
• 3 types, _______________________________________________________________________
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triggering of more than one cone is interpreted by brain as different colors
e.g. if both red and green are activated, the brain will interpret the light as yellow or orange
• ________________ than cones
• mostly found in ___________________________________
Responsible for color and fine detail vision – including reading
Color blindness is usually caused by the
absence of one or more cones.
•
Occurs in ~5% of population
•
X-linked trait … much more
common in men
Refraction and Accomodation
Light is bent – or __________________________– by nearly every eye structure that it passes through on the way to the
retina.
However the lens is the only structure that can vary how much the light is bent in order to allow us to focus on different
objects – a process called __________________________.
•
At rest, our eyes naturally focus
on far-away objects.
•
However, by contracting the ________________
____________________, we can make the
lens bulge so that it has greater
refractive ability – allowing us to
focus on close items.
As we get older, our lens loses elasticity – making it harder to focus on nearby items.
This condition is called _____________________________(old eyes)
Refraction flips and reverses the light rays, forming an upside down and reversed image on the retina … but the brain
learns to interpret visual information correctly.