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anatomy of the special sense organs > vision 1 and 2 > Flashcards

vision 1 and 2 Flashcards

1
Q

3 layers of the eyeball

A

outer tunic
middle tunic
inner tunic

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2
Q

outer tunic

A

-consists of cornea and sclera
-is fibrous

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3
Q

middle tunic

A

-consists of choroid, ciliary body and iris
- is vascular and pigmented

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4
Q

inner tunic

A
  • consists of the retina
  • is neurosensory
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5
Q

cornea function

A

to refract light
- curvature of anterior corneal surface
- tear film
- corneal thickness

to transmit light
- regularly arranged epithelium
-absence of blood vessels

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6
Q

sclera function

A

provides rigidity
- to allow insertion of extra ocular muscles
- to maintain shape of eyeball
- opaque
- makes up the bulk of the outer coat

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7
Q

cornea epithelium

A

Stratified squamous mEpithelium
-because it’s in contact with the external environment. So cells are always sloughing off and being damaged.
- cells in this bottom layer of the epithelium will produce new cells which will migrate to the top to keep that barrier intact.
-These cells are stuck together very tightly.

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8
Q

cornea - Bowmans layer

A
  • Acellular - no cells
  • Made up of collagen fibres
  • People who have had this layer removed don’t seem to have any functional loss to vision
    Maybe provide rigidity but not sure
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9
Q

cornea - stroma

A
  • Thick layer - connective tissue
  • Collagen fibres are arranged parallel to one another
    ○ Makes the cornea transparent
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10
Q

cornea - descemet’s membrane

A

another layer of collagen fibrils

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11
Q

cornea - endothelium

A
  • Cuboidal cells
  • the endothelium is in contact with the aqueous humor.
  • it’s going to help transport substances into the cornea Like Oxygen and help get rid of waste products from the cornea into the aqueous humor.
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12
Q

sclera fascial sheath

A

connective tissue - eyeball is supported by it

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13
Q

sclera - episclera layer

A

tough - connective tissue - lots of collagen fibres

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14
Q

sclera - stroma

A

the same as the cornea except that the collagen fibers and randomly arranged and because the randomly arranged and not arranged in a parallel fashion, The stroma is not transparent

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15
Q

sclera - lamina fusca

A

Connective tissue

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16
Q

sclera - choroid

A

Part of middle layer of eye

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17
Q

avascular cornea

A
  • cornea has no blood supply
  • it is avascular and transparent
  • it receives nutrients from the aqueous humour and tear film - Oxygen dissolves inti the tear film and then into the cornea
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18
Q

anterior scleral perforations

A
  • anterior ciliary vessels
  • recti muscles
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19
Q

posterior scleral perforations

A
  • optic nerve
  • central retinal vessels
  • ciliary nerves and vessels
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20
Q

central scleral perforations

A
  • vortex veins
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21
Q

lamina cribrosa

A
  • the weakest part of the sclera
  • surrounds optic nerve
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22
Q

middle tunic - ciliary body

A
  • plays a key role in accommodation
  • produces and secretes aqueous humour
  • suspends the lens
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23
Q

middle tunic - choroid

A
  • vascular pigmented layer
  • allows passage of blood vessels and nerves to anterior segment
  • prevents unwanted reflection of light - has some melanin pigment in it
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24
Q

choroid: histology

A

long and short posterior ciliary arteries, anterior ciliary arteries, vortex veins

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25
Q

choroid stroma

A

blood vessels, connective tissue and melanocytes

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26
Q

choroid - Bruchs membrane

A

multilayered sheet with elastic core

Allows passageway of substances into and out of the choroid

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27
Q

ciliary body - ciliary muscle

A
  • 3 sets of smooth muscle fibres

These muscle fibres help with accomodation

28
Q

ciliary body - ciliary stroma

A

vascular connective tissue

goes into these finger-like processes called ciliary processes.
this whole region where you have ciliary processes is called Pars plicata

So the ciliary stroma goes into each one of these ciliary processes and each one
of the ciliary processes is lined by a double layer of ciliary epithelium

29
Q

ciliary body - ciliary epithelium

A
  • double layer
  • outer pigmented
  • inner non-pigmented
  • produces and secretes aqueous humour
30
Q

what happens when you look at something close to your face

A

when you look at something close to my face, my ciliary body will be contracting and when it contracts it moves in this direction towards the lens.
if the ciliary body is moving towards the lens the suspensory ligaments become really Slack and then the lens can become nice and fat.

31
Q

what happens when you look at something far away

A

when you look at something far away ciliary body relaxes.
- It falls back, the suspensory ligaments become taught and then the lens becomes nice and thick.

So it’s the ciliary muscle that helps to carry out that accommodation.

32
Q

what is the iris made up of

A

it’s made up of stroma Anteriorly and a double-layered epithelium posteriorly

33
Q

what does the iris control

A

the iris controls the amount of light that enters the eye - it has to dilate and constrict.

34
Q

how does the iris control the amount of light that enters the eye

A

it does through these muscles - the sphincter papilae is embedded within the stroma and it causes miosis - causes pupil to constrict

the opposite muscle is called dilator pupillae and it is part of this epithelial layer.
○ Dilate the pupil - Mydriasis

35
Q

what is the epithelium in the iris closest to the stroma called

A

myoepithelium

36
Q

when do miosis and mydriasis happen in the iris

A

miosis - Happens when the parasympathetic nervous system is activated

mydriasis - Happens when sympathetic nervous system is activated

37
Q

trabeculae - iris

A

Radiate from the pupil to the periphery of the iris
These are columns of collagen that radiates out.

38
Q

iris - collarette

A
  • Where the iris is quite thick
    • Divides the iris into 2 zones
      ○ Ciliary zone - most outer bit
      ○ Pupillary zone
39
Q

iris - flush’s crypts

A

the aqueous humour can enter and
exit the Flushs’ of the iris.

40
Q

inner tunic - the retina

A

site of transformation of light energy into a neural signal

it extends from the optic nerve posteriorly anteriorly to where the ciliary body is

41
Q

the retina - retinal pigmented epithelium

A
  • main job is to again absorb excess light so you don’t get such unwanted reflection.
    another one of their main jobs is to make sure that these photoreceptors - rods and cones Work well
42
Q

photoreceptors in the retina

A

Full of photopigment - every time light hits your eyes these photopigments change shape And then the rod and the cones gets rid of them from this end. So these photo pigments are then all just discarded.

43
Q

bipolar cells - retina

A
  • Neurons
  • Synapse with photoreceptors at one end and synapse with ganglion cells at other end
    -2 poles
44
Q

retina - horizontal cells

A
  • They’re found at the interface between the photoreceptors and the bipolar cells.
45
Q

amacrine cells - retina

A

found at the interface between the bipolar and the ganglion cells

46
Q

ganglion - retina

A

Multipolar neurones
- Its the axons of these ganglion cells that form the optic nerve

47
Q

retinal layers

A

ganglion cell layer
- inner plexiform layer
- inner nuclear layer
- outer plexiform layer
- outer nuclear layer
- layers of rods and cones

48
Q

outer plexiform layer of the retina

A

Outer plexiform layer is where you find the processes of the rods and
cones.

49
Q

inner nuclear layer of the retina

A

Inner nuclear layer - horizontal bipolar and amacrine nuclei make up the inner nuclear layer.

50
Q

inner plexiform layer

A

Inner plexiform layer - axons of horizontal, bipolar and amacrine cells

51
Q

outer nuclear layer- retina

A

Nuclei of rods and cones found in outer nuclear layer

52
Q

ganglion cell layer - retina

A

Ganglion cell layer - where the cell bodies lie

53
Q

retinal neurones - bipolar cells

A
  • 1st order neurones of the visual pathway
  • relay information from photoreceptors to ganglion cells
  • many different types
54
Q

ganglion cells

A
  • 2nd order neurones of the visual pathway
    -exit retina at the optic disc
  • axons form the optic nerve
  • optic nerve exits eyeball at lamina cribrosa
  • many different cell types
55
Q

amacrine cells

A

horizontal transfer of information
- modulates information reaching ganglion cells
- many different types

56
Q

horizontal cells

A

horizontal transfer of information
- able to effect inhibitory response
- several different types

57
Q

retinal pigmented epithelium

A
  • protective (forms part of blood retina barrier)
  • phagocytoses fragments from photoreceptor outer layer
  • metabolises and stores vitamin A
  • produces growth factors
  • pigments help to decrease excess scattering of light
58
Q

optic disc of retina

A

optic disc. That’s where all your ganglion cell
Are going to leave the retina.

59
Q

fovea centralis - retina

A

where highest concentration of cones are found

60
Q

aqueous humour

A
  • supplies metabolic needs of the lens and cornea
  • contains water, glucose, proteins, dissolved gasses and other nutrients
  • supports wall of eyeball and helps maintain its shape
61
Q

vitreous humour

A
  • helps maintain shape of eyeball
  • contains proteins, salts, acids, hyalocytes and 98% water
  • transmits light
  • contributes to the dioptric power of eye
  • supports lens
  • supports retinal layers
62
Q

segments of the eye

A

anterior segment
- anterior to the lens

posterior segment
- everything posterior to the lens

63
Q

chambers of the eyeball

A

anterior chamber - 0.2 ml
posterior chamber - 0.06 ml

64
Q

canal of Schlemm

A

aqueous humour goes through the trabecular meshwork before entering the canal of Schlemm

it is drained by 25-35 collector channels which eventually empty into anterior ciliary veins

rate of formation of aqueous humour is 1-2 microl/minute

65
Q

aqueous humour normal intraocular pressure

A

10-20 mmHg
determined by:
- rate of formation of aqueous humour
- rate of drainage through trabecular meshwork
- pressure in the episcleral veins

66
Q

glaucoma

A

poor drainage through the meshwork can cause increased intraocular pressure

this can lead to optic nerve atrophy and defects in the visual field

peripheral fields are lost first in glaucoma

67
Q
A

anatomy of the special sense organs (9 decks)

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