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18 Cards in this Set
- Front
- Back
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What is the function of the cornea?
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The transparent outer-layer of the eye through which light rays pass into the interior of the eye. contributes most extensively to eye's refractive ability.
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What is the Lens/Ciliary body?
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the lens is between the aqueous humor and the vitreous humor; attaches to ciliary muscle by suspensory ligaments.; provides variable refractive ability during accommodation.
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What is the Iris?
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A thin pigmented smooth muscle that forms a visible ring-like structure within the aqueous humor. Varies size of pupil by variable contraction; responsible for eye color.
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What is the Aqueous Humor?
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The Aqueous humor is a clear, watery fluind, that is in the anterior cavity between the cornea and lens. the aqueous humor carries nutrients for the cornea and lens, both of which lack a blood supply.
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What is the Vitreous Humor?
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The rear cavity between the lens and retina contains a semifluid, jellylike substance called the vitreous humor. It is important in maintaining the spherical shape of the eyeball.
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What is the Retina?
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innermost layer of the eye; contains the photoreceptors (rods and cones)
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What is the Choroid?
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The middle layer underneath the sclera is the highly pigmented choroid. It prevents scattering of light rays in eye; contains blood vessels that nourish retina; anteriorly specialized to form ciliary body and iris.
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What is Refraction?
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The bending of a light ray is known as refraction. When light hits another medium at any other angle other than perpendicular is changes direction. With a curved surface such as a lens, the greater the curvature the greater the degree of bending and the stronger the lens.
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What does the Retina have to do with Refraction?
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the photoreceptors in the eye are only sensitive to wavelengths between 400 and 700 nanometers..this is known as visible light. They hit the sensitive retina to provide an accurate image of the light source.
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What are Photoreceptors?
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Rods and Cone Cells. They consist of three parts
1. An outer segment which lies closest to the eye's exterior, facing choroid. It detects light stimulus. 2. An inner segment, which lies in the middle of the photoreceptor's length. It contains metabolic machinery of the cell. 3. A synaptic terminal, which lies closest to the eye's interior, facing the bipolar cells. It transmits the signal generated in the photoreceptor on light stimulation to these next cells in the visual pathway. |
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What are bipolar cells?
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A retinal layer in the middle layer.
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What are Ganglion Cells?
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The inner layer of the retina.
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What is the optic nerve?
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The optic nerve leaves each eye at optic disc (blind spot)
it is the first part of visual pathway to the brain. |
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What is the Visual Cortex?
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neural messages are sent to the visual cortex in the occipital lobe of the brain. They are only sent to the visual cortex from photoreceptors that are "turned on" suffieciently by light to bring to threshold the ganglion cells to which they are "wired."..thus the resulting image perceived by the brain depends on the pattern of light striking the photoreceptors.
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What are Rods?
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Rods are photoreceptors in outermost layer of retina; responsible for high-sensitivity, black-and-white, and night vision.
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What are Cones?
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Cones are photoreceptors in the outermost layer of the retina..they are responsible for high acuity, color, and day-vision.
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What is Color Vision?
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the perception of the many colors of the world, depends on three cone types various ratios of stimulation in response to different wavelengths.
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What is color blindness?
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When individuals lack a particular cone type, so their color vision is a product of the differential sensitivity of only two types of cones.
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