Eye Flashcards
Which does the outer, fibrous layer of the eye contain?
sclera (white part)
cornea (window of the eye)
What does middle, Vascular tunic or layer contain?
- choroid-pigmented
- ciliary body-suspensory ligament that holds the lens in place
- Iris- “colored” and surrounds pupil (hole)
What does the inner, neural tunic or layer contain?
-pigmented layer of retina
*retina = photoreceptors
inter most layers = rods and cones
-optic disc = blind spot (lacks photoreceptors
-macula lutea with fovea antralis
what gland produces tears?
Lacrimal gland
What is the opening in center of the iris?
Pupil
what focuses light on retina and performs accommodation to view close-up objects?
Lens
which structure contains photoreceptors (rods and cones)?
Retina
What is clear, anterior portion of fibrous layer that constantly refracts light waves coming into the eye?
Cornea
What is the pigmented area around the pupil; controls amount of light entering eye?
Iris
What is the portion of external ear made of elastic cartilage?
Auricle/ Pinna
What is the term for the bones of middle ear?
Ossicles
What is the portion of the inner ear that houses receptors for hearing?
Cochlea
What tube connects pharynx (throat) and tympanic cavity?
Auditory or Eustachian tube
What segment of the eye is
-Filled with jelly-like vitreous humor
-helps focus light on retina
-supports & helps maintain shape of eyeball
-holds retina in place against choroid
Posterior Segment (larger)
What divides the eye into an anterior and posterior segment?
Lens & Ciliary body
What segment is
Divided further into:
-Anterior Chamber: anterior to iris
-Posterior Chamber: posterior to iris and anterior to lens
-Filled with Aqueous Humor
Anterior Segment (smaller)
What is called when production exceeds drainage, excess fluid puts pressure on retina & optic nerve?
Glaucoma
May lead to blindness if not treated
What happens to the pupil in bright light?
In bright light (pupil gets smaller) - circular, sphincter fibers contract & pupil constricts to reduce amount of light entering eye. (PSNS function)
What happens to the pupil in dim light?
In dim light (pupil gets bigger)
– radial, dilator fibers contract to pull pupil open to increase amount of light entering through pupil. (SNS function).
What does your pupil do when you view close up objects?
Pupils constrict
Contraction/relaxation of muscles of ciliary body can cause lens to change shape to focus light on retina is called what?
Increase in thickness increases refraction of light passing thru the lens.
Accommodation
What absorbs photons to prevent light from scattering within eye; important for high acuity vision; also produces Vitamin A?
Pigments in choroid
What lines the posterior chamber of eye from ora serrata to optic nerve?
Neural Layer
What is single cell thick; lines posterior chamber?
Pigmented layer of Retina
What are the two types of Photoreceptors?
One is (sensitive to dim light) &
the other is (3 types; high-acuity color vision)
Rods and Cones
Which cells pass nerve signals from photoreceptors to ganglion cells?
Bipolar Cells
Which cell axons of ganglion cells converge to form the optic nerve?
Ganglion Cells
What are axons of optic nerve exit eye; lacks photoreceptors; aka “Blind Spot”?
Optic Disc
What are more numerous (> 100 M); distributed throughout peripheral retina; sensitive to dim light; blurry vision due to convergent pathways?
Rods
What have only 10M; concentrated in fovea centralis; provide high-acuity color vision when stimulated by high-intensity light; unique pathways (one-for-one between cones, bipolar cells and ganglion cells)?
Cones
Pathways of Light through the eye:
Lens
Cornea
Aqueous humor
Vitreous humor
Fovea centralis of retina.
- Cornea
- Aqueous humor
- Lens
- Vitreous humor
- Fovea centralis of retina.
What occurs when we move from dim to bright light?
Rods become inactive; cones are initially overstimulated. After a few minutes, use of photopsins reaches equilibrium with regeneration and vision recovers.
Light Adaptation
What occurs when we move from well-lit areas to the dark?
-Cannot see well initially because:
-light levels are too low to stimulate cones;
-rods are still photobleached
-Rhodopsin slowly begins to accumulate once out of bright light; vision slowly improves (over hours)
Dark Adaptation
