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44 Cards in this Set
- Front
- Back
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What is adequate stimulus for the visual system?
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Light waves between 400 and 700 mm
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What are the three layers surrounding the eyeball?
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1. Sclera
2. Choroid 3. Retina |
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What is the sclera? What is it composed of?
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The stiff outer layer of the eyeball composed of dense connective tissue
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What is the cornea an extension of?
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The sclera
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Where does the cornea sit?
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Over the opening of the sclera anteriorly
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What is the choroid?
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A vascular coat that contains vessels and is pigmented in the eyeball
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The iris is a continuation of what structure?
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The choroid
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The iris contains smooth muscle that regulates what?
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The size of the pupil
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What is the central opening in the iris called?
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The pupil
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What muscle makes the pupil smaller?
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The pupillary sphincter
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What nerve innervates the pupillary sphinctor muscle?
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Parasympathetic nerve from the nucleus of Edinger-Westphal
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How are the fibers of the pupillary dilator muscle arranged? What happens when they contract?
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Arranged radially around the pupil, pupil widens when fibers contract
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Is the pupillary dilator muscle under sympathetic or parasympathetic control?
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Sympathetic
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The ciliary body is a continuation of what structure?
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The choroid
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The ciliary body contains smooth muscle that controls what structure?
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The lens
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Contraction of the ciliary muscles causes what to happen to the lens?
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Contraction causes threads attached to the lens to slacken so the lens becomes rounder
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What is presbyopia?
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Difficulty accommodating and reading fine print because the lens becomes stiff and no longer adjusts adequately
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What happens to the lens with age?
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It becomes more stiff
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How does the lens accommodate to see something far away?
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It becomes flatter
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How does the lens accommodate to see something close-up?
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It becomes rounder
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What is emmetropia?
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Proper vision
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What is hyperopia?
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Farsightedness, the lens cannot accommodate to near objects
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What is myopia?
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Nearsightedness, the lens cannot accommodate to far objects
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What is the innermost layer of the eyeball?
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The retina
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What part of the retina is pigmented and why?
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The outer part is pigmented to absorb the light that is not absorbed by retinal cells
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Where is the anterior chamber of the eye?
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In front of the lens
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What is the posterior chamber of the eye filled with?
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A clear jelly-like substance called the vitreous body
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What is the fovea centralis?
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The area of the eye where the density of photoreceptors (rods and cones) is highest
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What is the optic disc?
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Where axons mediating vision leave the eyeball, region is free of photoreceptors so it creates a blind spot
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What are the retina and visual fields divided into?
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Nasal and temporal parts
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The nasal halves of the retina receive light from what part of the visual field?
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The temporal parts
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The temporal halves of the retina receive light from what part of the visual field?
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The nasal parts
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What is the binocular portion of the visual field?
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The portion of the visual field where light falls upon both retina
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What structure blocks the visual field, causing monocular zones?
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The nose
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Why is the image on the retina upside down?
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Due to the refraction of light as it passes through the lens
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Light from the upper part of the visual field falls on what part of the retina?
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The lower part
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What is the blind spot?
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The area where axons gather to form the optic nerve and where there are no photoreceptors
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Why isn't the blind spot noticeable?
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It is in a different location in each eye, so it's not noticeable when both eyes are open
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What are the layers of the retina?
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1. Outer segments of rods and cones
2. Outer nuclear layer 3. Inner nuclear layer 4. Ganglion cell layer 5. Outer plexiform layer 6. Inner plexiform layer |
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What is in the outer nuclear layer?
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Cell bodies of rods and cones
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What is in the inner nuclear layer?
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Cell bodies of bipolar cells and interneurons
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What is in the ganglion cell layer?
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The cell bodies of ganglion cells
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What is in the outer plexiform layer?
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Synapses between photoreceptors and bipolar cells
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What is in the inner plexiform layer?
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Synapses between bipolar cells and ganglion cells
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