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SF2- Exam 3 > Histology of Eye > Flashcards

Histology of Eye Flashcards

1
Q

What are the three main coats of the eye?

A

External Layer: fibrous coat, supportive function, inelastic

  • sclera: opaque white
  • cornea: transparent

Middle Layer: vascular, highly pigmented

  • choroid: melanized, brown, richly vascularized, nutritive
  • ciliary body: ciliary muscle, lens focus
  • iris: pigmented area, eye color

Internal Layer: retinal coat

  • neural retina: rods, cones (photoreceptors)
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2
Q

What is the region behind the lens composed of water (99%), collagen, and hyaluronic acid molecules?

A

Vitreous body

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3
Q

Which layer of the eye is being described below?

  • thick layer of DICT
  • protects, maintains shape
  • fibrous coat, supportive function, inelastic
  • opaque white
A

Sclera

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4
Q

Which layer of the eye is being described below?

  • layer of loose connective tissue
  • melanocytes – melanized, brown, absorption of stray light
  • blood vessels, richly vascularized, nutritional
A

Choroid

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5
Q

What is the function of the retinal epithelium?

A
  • Absorbs light, pigment granules
  • Prevents back reflection of light striking retina
  • Forms part of blood-retinal barrier – tight junctions
  • Sustains metabolism/pigment turnover of photoreceptors
  • Outer segment turnover –

phagocytose shed discs

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6
Q

What are the photoreceptors of the eye? What does each receptor detect?

A

Rods:

  • low light intensity
  • images in shades of gray

Cones:

  • color, detail
  • higher light intensity
  • 3 types:
    • blue
    • green
    • red
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7
Q

Name the components of the eye.

A

NOTE: The pupil isn’t morphological structure its just an opening created by the iris.

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8
Q

What are the components of the posterior eye?

A

Sclera, layer of the choroid, and the retina where there is pigment epithelium

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9
Q

Label

A
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10
Q

Label

A
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11
Q

What is the function of melanocytes found in the choroid?

A

prevent the reflection of incident light

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12
Q

Many of the nutrients for the retina come from _________blood vessels.

A

choroid

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13
Q

The sclera is a dense layer of connective tissue rich in fibers of collagen type _________, arranged in parallel bundles.

A

I

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14
Q

What are the layers of the retinal pigment epithelium?

A
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15
Q

The retinal pigment epithelium is ______ (neuronal/nonneuronal).

A

Non-neuronal

*The neuronal components of the eye are the optic nerve and the retina

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16
Q

Describe the rods and cones, in terms of axons and dendrites.

A

•They have a cell body, dendrite at one end and a short axon at the other end

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17
Q

The axons of the ganglion cells leave the eye in the _____________.

A

Blind spot (optic papilla)

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18
Q

What are the functions of the retinal pigment epithelium?

A
  • Absorbs light, pigment granules
  • Prevents back reflection of light striking retina
  • Forms part of blood-retinal barrier – tight junctions
  • Sustains metabolism/pigment turnover of photoreceptors
  • Outer segment turnover –

phagocytose shed discs

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19
Q

What component of the retinal epithelium absorbs light to prevent reflection of light from striking the retina?

A

Pigment granules

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20
Q

Which photoreceptor is being described below?

  • low light intensity
  • images in shades of gray
A

Rods

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21
Q

Which photoreceptor is being described below?

  • color, detail
  • higher light intensity
  • 3 types:blue, green,red
A

Cones

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22
Q

The retina produces graded potentials instead of action potentials. True or False

A

True

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23
Q

There are no structural junctions between the retina pigment epithelium and photoreceptors. True or False

A

True

They just sit on top of each other but there is no junction. This can cause detached retina that would need to be repaired.

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24
Q

Between the RPE and the choroid there is a structure called ___________ which separated these two.

A

Bruch’s membrane

*Bruch’s membrane thickens with age, slowing the transport of metabolites. This may lead to the formation of drusen in age-related macular degeneration.

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25
Q

The dendrites and axons are referred to as ___________ layers.

A

plexiform

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26
Q

Label

A
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27
Q

The choroid is especially thick in the ___________ region.

A

Macular

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28
Q

The fovea is surrounded by the _____________ which is characterized by yellow pigment/ xanthophyll pigments.

A

macula lutea

29
Q

What is the function of the macula lutea?

A

•They absorb short wavelength light, so it absorbs extra blue and UV light which is damaging. So it is like natural sunglasses to protect the fovea.

30
Q

___________ is the spot in the retina that lies on the posterior cord of the optical axis. It is a shallow depression with a very thin retina in the center. The bipolar cells and ganglion cells have been pushed to the sides and aren’t in the depression.

A

Fovea

31
Q

What are some characteristics of the fovea?

A
  • highest visual acuity
  • thinnest retinal region
  • highest packing density
  • pure cone photoreceptor region

REMEMBER: Bipolar and ganglion cells are not located in the fovea

32
Q

Lack of photoreceptors in the macula lutea and the fovea area can result in which disease?

A

Age-related macular disease

*Increased accumulation of debris in Bruch’s membrane, which is between the choroid and the RPE. You have debris accumulating and that somehow affects the photo receptors and causes damage.

33
Q

Label

A
34
Q

Label

A
35
Q

Where do the axons of ganglion cells exit the eye ball?

A

Blind spot (optic papilla)

36
Q

Directs light rays to __________ (converge/diverge) on retina.

A

Converge

37
Q

___________ is the main site of refraction and light bending

A

Cornea

*If the cornea isn’t shaped right the light will converge too early or too far behind the retina so you can’t see as well. It is transparent, avascular, and this is where light is focused.

38
Q

What type of epithelium covers the cornea?

A

Stratified columnar epithelium

39
Q
A
40
Q

Label

A

Cornea

41
Q

The superficial epithelium of the cornea is composed on what type of epithelium

A

Stratified non-squamous epithelium

42
Q

The __________ of the cornea, which is the substantia propria which is DRCT, makes a thin lamella around fibroblasts.

A

stroma

43
Q

Label different layers

A
44
Q

What is the function of the corneal epithelial cells?

A

•The cornea endothelial cells actively pump fluid from the stroma into the anterior chamber. These cells pump bicarbonate ions from the cornea into the anterior chamber, and the water that is in the stroma follows into the anterior chamber osmotically.

  • This works to keep the stroma partially dehydrated, otherwise you would get a very opaque cornea and if something happens to the endothelial cells or there are holes in the endothelial layer, there might be water coming into the cornea that would make the cornea opaque and you would need to get a corneal transplant.
45
Q

Light bending occurs in the ________.

A

cornea.

46
Q

What kind of tissue make up the cornea?

A

Dense regular connective tissue

47
Q

The _________ separates anterior and posterior chambers.

A

Iris

*The iris is a structure and it determines the size of the pupil (which is just an opening) when the iris contracts or relaxes it will change the size of the pupil.

48
Q

As the retina moves to the front of the eye it thins down into two layers that covers the___________ and the back of the________. What was several layers of cells will form two layers that will cover those two structures.

A

ciliary bodies; iris

49
Q

Label

A

Iris

50
Q

Label

A
51
Q

Pigment epithelium of the iris doesn’t give us our eye color, that is determined by the density concentration of the melanocytes in the ____________.

A

stroma.

52
Q

Pupil constricts as ___________muscles contract.

Pupil dilates as ___________muscles contract.

A

circular; radial

53
Q

The muscles that constrict the pupil are innervated by ________ (parasympathetic/sympathetic) fibers

A

Parasympathetic

54
Q

The muscles that dilate the pupil are innervated by ________ (parasympathetic/sympathetic) fibers

A

Sympathetic

55
Q

Label

A

Iris

56
Q

Label

A
57
Q

What is the primary function of ciliary muscles?

A

Accomadation

58
Q

Ciliary processes secrete ______________.

A

Aqueous humor

59
Q

What is the purpose of the suspensory ligaments?

A

The suspensory ligament (zonula fibers) connect the ciliary body to the lens so you can control the lens shape.

60
Q

Aqueous humor is secreted by the ciliary processes, goes into the posterior chamber and runs around the iris and covers the anterior structures and is drained via the _____________.

A

Canal of schlemm.

61
Q

Opacity in lens leads to _____________.

A

Cataracts

62
Q

What is the function of the lens?

A

–image focusing component; highly elastic

–age-dependent loss of elasticity

–changing shape to bring into focus divergent or more parallel rays

63
Q

What type of epithelium makes up the lens?

A

Cuboidal

64
Q

Overtime lens lose their organelles. What other cells lose organelles?

A

RBC

keratinocytes

65
Q

Label.

A

Section of the Anterior portion of the Lens

66
Q

The subscapsular epithelium will move from polar region to equatorial region to make the _____________.

A

lens cell fibers

67
Q

What is the flow of aqueous humor?

A
  1. Secreted into posterior chamber
  2. Flows into anterior chamber
  3. Filters thorugh trabecular meshwork
  4. Drains into Canal of Schlemm
68
Q

Clogging of the trabelular meshwork leads to ___________

A

Glaucoma

*Clogging of the trabecular meshwork leads to an increase in intraocular pressure

  • The eye can’t change its shape because of the strong sclera that is around it so you get an increase in intraocular pressure and then the optic nerve is pressed on.
69
Q

Label

A

SF2- Exam 3 (12 decks)

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