The senses - sight - functions & structures of eye - ch 13 Flashcards
what is the primary function of the eye?
to capture light rays
What are the light rays modified into?
nerve impules
Where are the nerve impules transferred to?
the visual cortex of the brain
What is the role of the visual cortex of the brain once it receives the nerve impulses?
to translate and interpret into images to enable a person to see.
Name the functions of the eye?
- light perception
- focusing of the light onto the retina
- refraction
- light accommodation
- transmissions of messages to the brain
- production of tears
Name the first part of the eye that light first passes through?
cornea
Describe the cornea?
curved clear outer portion of the eye
What is the role of the cornea?
It focuses light through the pupil, a round hole located in the centre of the iris.
Once the cornea has focused light through the pupil through the centre of the iris, what is the iris responsible for?
the iris controls the diameter and size of the pupil and therefore regulates the amount of light that can reach the retina.
Do muscles attached to the iris expand or contract the pupil depending on how much light is present.
Yes, the larger the pupil the more light enters
Describe what happens when light passes through the lens?
Muscles in the eye cause the shape of the lens to become thicker or thinner to focus light on the fovea centralis which is in the middle of the macula on the retina at the back of the eye.
Describe the process of refraction?
As light passes through the lens, muscles in the eye cause the shape of the lens to become thicker or thinner to focus the light on the fovea centralis, which is in the middle of the macula on the retina at the back of the eye.
What does the retina convert the light into?
electric signal.
What is the process of the electric signals that has had light received by the retina?
electric signals travel via the optic nerve to the brain stem and then to the visual cortex in the occipital lobe, where it is translated into an image.
What is the orbit?
The orbit is the eye socket
Where in the body do you find the orbit?
in a space adjoined by the bone of the cheek, the forehead, the temporal bone and the side of the nose.
What is the role of fat pads found within the orbit?
to protect the eye
What is the name of the gland found in the orbit?
lacrimal gland
Where do you find the lacrimal gland?
under the outer portion of the upper eyelid
What is the role of the lacrimal gland?
to produce tears to lubricate and moisten the eye and help clear the eye of any foreign matter, such as dust.
What is the name of the duct that tears are drained away from?
nasolacrimal duct found in the inner corner of the eye
Describe an eyelid?
a thin fold of skin that covers the eye
What is the role of the eyelid?
to protect the eye from foreign bodies and bright light
How does the eyelid protect the eye?
By keeping the eye moist through the operation of blinking which spreads tears across the eye’s surface.
What is the role of eye lashes?
To help filter out dust and debris and prevent sweat from getting into the eye
Describe the Sclera of the eye?
the protective outer wall of the eye
Describe what the Sclera is made up of?
strong, fibrous tissue that expands from the cornea to the optic nerve.
Describe what the sclera gives to the eye?
its white colour and its shape.
Name the muscle that the sclera is attached to?
the extraocular muscle
What is the role of the extraocular muscle?
it moves the eye from side to side, up and down and diagonally.