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A&P II > Special Senses- Eye > Flashcards

Special Senses- Eye Flashcards

1
Q

Extrinsic components

A

Lid, brow,lash, extrinsic eye muscle, exocrine gland, lacrimal glad, conjunctiva, rectus muscle

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2
Q

Eyelid

A
  • neuromuscular reflex control
  • maintain integrity of corneal surface and tear film
  • maintain proper position of globe within orbit
  • sensory function of lid
  • spontaneous and reflex blinks
  • regulates light
  • cosmeis ( cosmetics)
  • obicularis occuli- moves eyelid
  • protection from outside environment ( squint)
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3
Q

Conjuctiva

A
  • over sclera
  • spreads tear film
  • mucus membrane ( open to outside world) barrier, keeps anterior moist
  • thin, translucent
  • epithelium continuous with cornea and. Lacrimal drainage
  • it is- pink eye
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4
Q

Cornea

A

Responsible for 70% of focus capabilities

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5
Q

Lacrimal apparatus

A

Produces tears, float to anterior surface of eye

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6
Q

Lacrimal gland

A

Natures eye drop , produces film, secretes fluid,lid movement, moves fluid over anterior eye

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7
Q

Tear film

A 
Primarily tears 
Helps cornea focus light
Maintains health of underlying structure
Maintains optical stability
Antibacterial 
Corneal nutrition
Mechanical- flushes cellular debris
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8
Q

Extrinsic eye muscle

A

6 attach to outer surface of eye
Produce movement
Controlled by cranial nerve 3,4 and 6

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9
Q

3 tunics

A

Fiberous- outer
Middle- vascular
Inner- nervous tunic

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10
Q

Fiberous-

A

Dense CT, outer covering of eye

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11
Q

Sclera

A

Rigid makes up majority of fiberous

Protects internal structures

Maintains eye shape

Covers anterior, except cornea

Allows for muscle attachment

Focus capabilities composed of elastic and collagen

Extrinsic muscles attach to fiber tunic

Sclera is similar to muscle fibers firm attachment

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12
Q

Fiberous- Cornea

A 
A vascular
5 layers
Common transplant
Light bends ( refracts) on to lens
Filters out UV light
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13
Q

Fiberous- scleral venous sinus- vein- where cornea and sclera intersect

A

Absorbs excess aqueous humor

Drains AQueous humor to maintain eye pressure

Intraocular pressure in front of lens, built up pressure helps keep retina attached.

Detached retina- too little pressure

Back pressure- blindness/glaucoma

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14
Q

Middle tunic

A

Vascular

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15
Q

Middle- vascular parts (3)

A
  1. Choroid- primary blood supply to retina- nourishes, posterior between sclera and retina (layer), highly pigmented- dark in color, melanocytes, vascular loose CT, blocks light from sides. Thickness decreases from posterior to anterior. Protects retina from invading blood vessels
  2. Ciliary body- anterior extension of choroid, 2 functions- accommodates- change shape of lens/focus power- extends fibers towards lens. Contraction results in thickening of lens which focuses on close objects. Change shape/ focus power of lens .-also so Ulta fibers secure lens in place. Process- holds lens, makes aqueous humor muscle- shapes lens by contracting and relaxing- refraction power
  3. Iris- positioned in front of lens, thin, pigmented- epithelial and smooth muscle. Controls size of pupil- regulating light entry. Bright- parasympathetic- constricts— sympathetic-dim- displayed. Surrounded by aqueous humor. Gives color

Lens- not part of vascular works with it. Maintains clarity- refraction (bending) light focused- provides accomodation- focusing @ different distances, absorbs UV — where cataracts form, refraction

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16
Q

Nervous tunic

A

Inner most layer of eye

17
Q

Nervous tunic- retina

A

Thin, transparent, where photoreceptors detect change in light are found

Only rods and cones respond directly to light

18
Q

2 types of photoreceptors

A

Rods and cones

19
Q

Rods

A

Elongated, contain pigment rhodopsin which can absorb dim light and can detect shades of grey in dim light.

Achromatic- without color

Inner segment contains nucleus- metabolic machinery

Outer segment is transduction sites

Chemicals interact with light waves to create impulse— action potential

Consist of high density stack of disk membrane - flat organelles

20
Q

Cones- photoreceptors

A

Contain photopsin- absorb bright light- allows us to see colors in bright light

Chromatic(color)

3 types of photo pigments s cone ( blue), m cones (green) and L (red) cones

Missing cones means color blind, can’t convert light wave to color

We cannot see below infrared or above UV

Recover more rapidly than rhodopsin (50%) in 1.5 min

21
Q

Landmarks of Retina

A

Central fovea and macula ( area around fovea) . Free of blood vessels contains only cone cells - 99% in retina- sensitive

Optic disc- blind spot, where optic nerve and retina attach- no rods or cones- no images, no transduction

Anterior cavity- in front of lens

Posterior cavity behind lens

Virtuous humor- maintains retina placement and distributes pressure and fluid over retina

22
Q

Processes of retinal image formation

A

All happen at the same time

23
Q

Process of retinal image formation

Refraction

A

Bending light rays . Refracted light can be focused. End point- central fovea

Disorders- myopia- near sighted- in front of retina
Astigmatism- distorted
Hyper metro pia- far sight, behind retina
Emotropic normal eye

Refractive structure- 1 cornea 70% 2. Aqueous humor(focus) 3. Lens- only one that can be adjusted- moment to moment(accommodation)- suspended by zonules of zinn 4. Virtuous humor- shock absorb

Presbyopia- difficult accommodating — different glasses for driving, reading etc

24
Q

Process of retinal image formation

Accommodation

A

Eye changes refractive power. - curve and thickness increase/decrease lens size- accounts for distance- far lens is flat, close lens is thick and round

25
Q

Process of retinal image formation

Pupil constrict and dialate

A

Parasympathetic- constrict- bright

Dilate- sympathetic -ANS- dim dark light- regulates amour of light entering

26
Q

Process of retinal image formation

Convergence

A

Convergence- intersect- disgujate (rotation in opposite direction) focus on 1object- rotate eyes toward nose

Movement of eye move inward so line of sight intersect in front of eye aka- synchronous adduction of each eye

Helps maintain bifoveal single vision. Focus of eyes on same object at same time

27
Q

Visual transduction

A

Ability to convert stimulus (light)into nerve impulse (action potentials) rods and cones are the only reason this is carried out

28
Q

Binocular vision

A

Both eyes focusing on the same object— giving us convergence

29
Q

Increased field of vision, enhanced visual acuity, contrast sensitivity, visual motor skills

A

Optical defects in one eye Mae less obvious by other eye safety net from vision loss- depth perception, cross eye, lazy eye would be negative effects here

30
Q

Bison happens in occipital lobe via visual pathway

A

PathwY- photoreceptors of retina— cranial nerve 2(optic)- where nerve crosses optic chiasma-optic tracts-optic radiation (thalamus)—visual cortex of occipital lobe

A&P II (11 decks)

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