Flashcards in Chapter 10—Special Senses Deck (48)
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Describe the lens.
The lens is biconvex and flips images on retina when viewed.
(We must "learn" to flip them right-side up again in brain)
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Humans have binocular vision. What does this mean?
We see because of the overlapping of 2 visual fields—left and right
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List tunics in order from outer to inner.
Sclera
Choroid
Retina
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Describe the sclera.
It is the white, fibrous part of eye.
It includes the cornea.
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What is the cornea? How does it receive nutrients?
Clear, anterior portion of eye that contains lots of nerve endings.
Nutrients through diffusion.
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Describe the choroid.
Darkly pigmented part that prevents light from scattering in the eye.
*blood-rich
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What does the middle tunic include?
Choroid=ciliary body and iris
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What is the ciliary body?
Smooth muscle structure to which the lens is attached. Controls the movement of the lens.
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What is the iris?
Colored muscle that contains the pupil.
The circulatory and radially arranged smooth muscles act like the diaphragm of a camera.
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What is the pupil?
Rounded opening through which light passes. Regulates amount entering
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What is the retina?
Innermost layer with photoreceptors.
(Rods & Cones)
Extends anteriorly onto ciliary body
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What are gross eye movements controlled by?
Extrinsic eye muscles
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What kind of vision do rods help with? Cones?
Rods-Black and white
Cones-Color
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Why can't you look directly at a dim star and see it?
How could you see it?
Rods, which would be responsible for seeing it, are in the periphery. Cones are the ones in direct vision.
Look at it with peripheral vision.
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What is the optic disk?
Where the optic nerve leaves the eyeball (blind spot) *no photoreceptors here.
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What wavelengths to human cones detect?
Red, blue, and green
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What color is the iris in an albino?
Red...no color so choroid is seen
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What are cataracts?
Result from hardening of the lens. Causes vision to become hazy and blindness can result
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What is colorblindness?
Lack of three cones.
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Glaucoma?
Is the result of Aqueous humor not being reabsorbed into venous blood through canal of Sclemm. Drainage is blocked and pressure builds up.
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Fovea centralis?
Area of sharpest vision
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Aqueous humor? Where found and what it does?
Behind cornea
Helps maintain appropriate pressure in eye
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Vitreous humor?
Posterior to lens
Gel like substance; round shape of eye
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What is the job of the meibomian glands?
Secretes oily substances to lubricate eye(modified sebaceous glands)
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What is pinkeye? What is it caused by?
Conjunctivitis
Caused by bacteria getting in and causing inflammation
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What is accommodation?
Adjustment of lens to let us see close objects
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Convergence?
The eyes move medically when we view close objects.
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External ear?
Pinna(auricle)
External auditory canal
Tympanic membrane(eardrum)
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Middle ear?
Ossicles
Auditory tube (the Eustacian tube)
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